Hello,
You are given that the complex number alpha = 1 + j satisfies the equation z^3 + 3z^2 + pz + q = 0, where pand qare real constants. (i) Find and in the form a + bj. Hence show that and p = -8 and q = 10 [6] (ii) Find the other two roots of the equation. [3] (iii) Represent the three roots on an Argand diagram. [2]
Thanks guys as always. DR Jp.
How much time is needed to travel around the world for the following modes of transportaion -- the space shuttle, a jet airliner, a cruise ship
I have a group of 12 observations. I'd like to predict what my observations will be in the future. I also need the distribution to apply Bayes Theorem.
Right now, I'm using the normal distribution but I don't know if that's the right choice. I've calculated the skewness and kurtosis of the data, but I don't have any idea what they're supposed to be! I mean, I know if my observations were truly normally distributed, the skewness would be zero, but I don't know if my skewness of 1.65 is "close enough" or what. Are there rules of thumb for this? moink 05:50, 1 June 2006 (UTC)
Ok, here is this little idea I had today. It has the potential of solving all problems of theoretical physics in one stroke of genius. Basically, the idea is that the interactions in the world are subject to very simple rules, namely Newtonian mechanics. But hey, I hear you say, wasn't there a guy called Einstein who has proven Newton wrong? Well, he did, but it would be Newton who will be having the last laugh.
The world of Newtonian mechanics is very simple: a Euclidean space and a few differential equations, solutions of which are nicely differentiable curves. There is one problem with this world: it is continuous, which makes its "implementation" extremely hard. There are no continuous things in our world: the space is discrete, the time is discrete, and this brings us to the next point: the world is a finite state machine. The world is, basically, a computer. The bit-twiddling aspect of our world is studied by quantum mechanics.
N-body problem is a classical problem of mechanics. There are a few particles floating around in space under the Newtonian law of gravity. It translates into a system of differential equations, which in general is not solvable by mathematical means. We'll try to simulate this problem on a computer. When n=2 theory states that these two bodies would have elliptic orbits (well, not exactly, the orbits may also be hyperbolic or parabolic, but we assume that they are ellptic). What happens when we simulate this on computer? At first everything seems okay, the smaller planet rotates around the bigger one. Let's modify the program so the path of the smaller planet is visible. Then, after a few rotations we'll see a strange effect: the elliptical orbit is slowly turning! More interesting is that the same thing happens in real life: a result predicted by General Relativity theory. But isn't it strange, that Newton's law of gravity when emulated on a computer produces the same effect?
There are several numerical methods for solving differential equations. They all have the same flaw: when you run the method for a long time, round-off errors and discretization errors build up and the result strays off from the right solution. The same thing happened in our simulation - during the rotation the error builds up as we do little discrete time steps, and it rotates the orbit. The same thing, I suspect, happens in our real world, which faithfully tries to solve Newton's differential equation by discrete means.
Comments are welcome. Grue 12:36, 1 June 2006 (UTC)
Any crypto fans here? I need to generate object IDs from other object IDs to mask the true object with one that is a plausible replacement.
Say I have a unique object ID, is there an encryption algorithm I can use against it to produce a different (cyphertext) object ID that is one way (can't easily get the original plaintext Object ID from the cyphertext Object ID, either not at all, or at least short of a computationally expensive attack), and unique, meaning that no 2 original plaintext object IDs produce the same cyphertext object ID and that I never get different cyphertext object IDs from the same plaintext object ID. The text lengths need not be the same I guess, although obviously the cyphertext one can't be shorter. I have looked at Message_digest and it speaks of cypher/hash functions that are unlikely to have different plaintexts go to the same cyphertext. I need guaranteed... the cyphertext length need not be a hash, it can be as long or longer as the original (exactly the same size would be convenient, though). thanks! + + Lar: t/ c 18:34, 1 June 2006 (UTC)
A method that gives good scramble of an N-bit string is to XOR it with a randomly chosen bit string, apply a randomly chosen permutation to the bits of the string, multiply modulo 2N with another random but odd bit string, and XOR+permute again (using different choices). Since each step is invertible, you are guaranteed to have no collisions. For additional security the procedure can be repeated. I have no idea how safe this is against various cryptanalytic attacks; for all I know there is a way of breaking the scheme that is obvious to more devious minds than mine. Use at your own risk. -- Lambiam Talk 14:53, 2 June 2006 (UTC)
What do you call this type of notation?
or
As far as I can remember, ∗ is always been one of Σ, Π, ∩, ∪, or ∐ (coproduct), but theoretically couldn't it be extended to apply to any binary operation? Or maybe even to any function?
I don't understand why this ubiquitous notation does not seem to have a name.
In statistical process control using control charts, I have noticed that presenters often recommend calculating the standard deviation in a, so to speak, nonstandard way. The recommended procedure is to calculate a mean moving range, i.e. , using a relatively small dataset, and then divide the mean moving range by the magic number 1.128. If you google for " (1.128 and calculate)" and are feeling lucky today, you will find a such a presentation. The number 1.128 is often represented by the symbol d2. Does anybody know the maths behind this non-standard estimator of the standard deviation? -- vibo56 19:00, 1 June 2006 (UTC)
Can anyone help me with the problem below. I am aware that it is a homework question, but that is why I don't want you to answer it! The question is to simplify it and I assume that you have to multiply out the parenthesises:
I obviously tried WP, but couldn't find the right article. Thank you very much. K ilo-Lima| (talk) 20:05, 1 June 2006 (UTC)
PLEASE I WOULD LIKE TO KNOW HOW THE Monte Carlo simulation techniques IS USED to evaluate the impact of DEM error on viewshed analyses.
What kind of substitution should I use? Patchouli 06:18, 2 June 2006 (UTC)
Patchouli 07:17, 2 June 2006 (UTC)
I have a question involving circular motion. Visualise a roller coaster's path. At the start, a straight part of length x, at an angle of 10° above the horizontal exists. A particle rolls down this, and meets an arc of radius 8m sloping downwards, and declines to a straight path 40° below the horizontal. The path is smooth and is only affected by gravity. I have to find the maximum value of x so that the particle stays on the path. I've only ever encountered particles with a mass, and this one has none specified, so I assume it cancels somewhere.
Anyway,
I'll figure stuff out from here.
Thanks. x42bn6 Talk 08:57, 2 June 2006 (UTC)
____ x 10° ˇˇˇˇ----____ ˇˇˇˇˇˇˇˇˇˇˇˇ _--ˇˇˇ--_ /ˇ ˇ\ | 8m |\ | ·<---->| ˇ\ | | ˇ\ \_ _/ 40° ˇ\ ˇ--___--ˇ ˇˇˇˇˇˇˇˇ
Why does this work?
1. First of all, pick the number of times a week that you would like to have chocolate (more than once but less than 10) 2. Multiply this number by 2 (just to be bold) 3. Add 5 4. Multiply it by 50 -- I'll wait while you get the calculator 5. If you have already had your birthday this year add 1756 .... If you haven't, add 1755. 6. Now subtract the four digit year that you were born. You should have a three digit number The first digit of this was your original number (i.e, how many times you want to have chocolate each week). The next two numbers are: YOUR AGE! (Oh YES, it is!!!!!)
I got it from ebaumsworld and it works for me. I find it really weird. Thanks. schyler 13:48, 2 June 2006 (UTC)
no, I put in 3 for how many per week and I'm 14 and I got 313,
1 → | 3 | 2 → | 6 | 3 → | 11 | 4 → | 550 | 5 → | 2306 | 6 → | 314 |
1 → | 3 | 2 → | 6 | 3 → | 11 | 4 → | 550 | 5 → | 2305 | 6 → | 313 |
I have a complex analysis exam coming soon, and I'm not very confident with Laurent series. Suppose I have a complex function f(z) which has a finite number of poles. Is there a general method for finding its Laurent expansion? Admittedly, my knowledge of Laurent series is somewhat limited. I know what they are, but not really how they work. Can anyone help? Maelin 03:12, 3 June 2006 (UTC)
I would like the definition and applications of a voronoid diagram (scatter application). Please put a definition on your web site.
what is the quadratic formula —Preceding unsigned comment added by 69.231.27.28 ( talk • contribs) 04:03, 2006 June 3
How do I search edit areas in Firefox? For example, when I edit a long article and want to find where it links to a specific category, the text entered into the search field seems to be searched for only outside the wikicode. Is there any way to get it straight? Conscious 06:07, 3 June 2006 (UTC)
I have Mathematica 5.0. What is the best way to transform the *.nb to a format that Wikipedia understands.
Given an integer n, what are the tightest bounds on factorial n? More specifically, I want to calculate the number of binary digits required to represent n! for a given n. -- Sundar \ talk \ contribs 10:37, 3 June 2006 (UTC)
Well considering that summation is cheap for computer, for relatively small n you can get a very good estimate by using
Consider a torus, cut a tiny CLOSED piece out on the side. So the piece I cut out is homeomorphic to .
What is the remaining space? My professor tells me I can only see it when i start stretching that hole open 'until my fingers touch on the other side'. However I was born with no 3D mind, I simply do not see it.
It should be an 'easy space involving cylinder(s)' I would like to understand this completely for the understanding of homotopy and homology groups.
Evilbu 11:35, 3 June 2006 (UTC)
Well uhm, what is a handle, my syllabus says every is a handle? The article http://en.wikipedia.org/wiki/Handle_%28mathematics%29 doesn't really help me out right now. Evilbu 12:16, 3 June 2006 (UTC)
I am very confused now. What do you mean, a cylinder attached at its two end circle, you mean take a cylinder, then attach the upper and lower circle? Wouldn't that be a torus? Why would the product of two balls be trivial? What is the union of twice Evilbu 12:44, 3 June 2006 (UTC)
Seems like I know much less than I thought. Is there a precise definition of handle (I am familiar with the language of quotient spaces) In order to make sure we understand each other, I will say a couple of things, and please tell me when you disagree : is the closed disk in two dimensions is the unit circle (it is one dimensional , the (empty,thus 2d)torus, is homeomorphic with the full,thus 3d torus is homeomorphic with
Maybe it would be relevant to say why I want this. I want to find the torus' homology groups, especially the group Now my professor told us to do a Mayer Vietoris trick on the torus, by cutting out a little piece (a disk) . The two spaces I get then, have a 'relatively easy' intersection in my Mayer Vietoris sequence, it is a cylinder, homotopic with a circle, and thus completely known. But what is the other space? Evilbu 15:31, 3 June 2006 (UTC)
Uhm, no I do not know anything of universal coefficient theorem. If it is relevant, we always consider these groups as modules, thus abelian groups. I know I cold do a Mayer Vietoris trick by using two cylinders, who intersection are two disjoint cylinders, then I find everything except Basically I was hoping by doing this cutting out of a little sphere, I would be able to find it in another way. Evilbu 09:47, 4 June 2006 (UTC)
Please help a new small manufacturing company by locating "indirect labor unit cost." We need this for our financial portion of the business plan as required by Small Business Administration. Our leaders, Maasters of Science in Healthcare, for some reason did not include this information. If anyone out there can help, it will greatly appreciated. Our company sews dresses and suits for premature infants and low birth weight infants. The SBA booklet indicates that this "cost" is needed to be included with total production costs.
This question may not be a typical for Wikipedia, but we have really been trying to find this and to date have not been successful.
Can someone give me a simple mathematical forumla sude in civil engineering? It's for a math homework project. Thanks in advance! -- Wizrdwarts 01:38, 4 June 2006 (UTC)
Catenary has a cool formula for suspension bridges... (and that is TYPICAL engineering right?) Oh by the way, you should write formula. Evilbu 10:48, 4 June 2006 (UTC)
Suppose you had the values of 1 to 100. Then, you randomly organized the 100 numbers into 10 groups of 10. One group might contain the numbers 7, 13, 17, 38, 41, 52, 59, 71, 90 and 95 for example. Then, by group, the highest number would be given a corresponding value of 10, the second highest a corresponding value of 9, and so on. Then, the process is repeated, and any value earned is added to the last value earned. For example, the number 100 will always be given a value of 10 (because it is always the highest number out of 100), so after 3 random "draws," its corresponding value would be 30. Likewise, the number 1 would have a value of 3 after 3 "draws." My question is: how many random "draws" would it take so that all the numbers were in numerical order based on their values. Likewise, how many random "draws" would it take so that less than 10 numbers were not in correct placement when organized by values. I understand that this question is confusing (and it is quite hard to word), so if you have any questions as to what I mean, then please ask and I will update and clarify accordingly. Thank you in advance for all of your help. - Zepheus 02:55, 4 June 2006 (UTC)
(1-10) (11-20) (21-30) ... (91-100) (1,11,21,31,...) (2,12,...) (3,13,...) ... (9,19,...) ... (10 times) ... (1,11,21,31,...) (2,12,...) (3,13,...) ... (9,19,...)
Some thoughts on the convergence of the order. Consider a random variable , the rank of number k in a random draw. Denote . Denote by the event that the numbers k and k+1 are in different groups, its probability is . Given , has the same distribution as , and is symmetric with respect to 0 ( for x>0), thus . With probability 1/10 the numbers k and k+1 are in the same group (, complementary to ) and and . That is,
Besides, we have
After realization of n draws, the numbers 1,...100 have the correct order if
It is known than in distribution so the convergence to the correct order should be expected. The questions arise whether the r.v. are independent of each other, and for which smallest n the event occurs the first time, and what is the distribution of such n. ( Igny 22:46, 4 June 2006 (UTC))
These mathematical functions are getting crazy. I wish I could decipher them. I'll definitely archive this page. One more question, the first answer I receive was that 11 draws would be sufficient. The next answer was that roughly 2,050 draws would be needed. How are these related? Also, what is the rough estimate for the number of draws needed for less than, say, 10 mistakes. - Zepheus 19:09, 5 June 2006 (UTC)
Okay. I understand now. Thanks for the update, and all of your hard work. - Zepheus 21:16, 5 June 2006 (UTC)
Can anyone recommend me loudspeakers for an integrated sound card (asus a7v8x-x) with a good quality/price ratio? thanks.
Hi,
I have yet again a topology inspired question. First of all though I would like to express my gratitude for the many people who have helped me here.
Right now I mostly receive from Wikipedia being a student in exams, but I have and I will again give to the community myself:)
I am confused about http://en.wikipedia.org/wiki/Free_product_with_amalgamation
Suppose I take a free product of the groups and the article states it should give me a free group on two generators. Now the article on free groups it links to says that free groups and free abelian groups are not the same. There goes my hope that it would be
but wait! , later that article says it is a coproduct of two groups in the categorical sense. But I was thought in my algebra class that for Rmodules, and thus also abelian groups (as they are the same as \mathbb{Z} modules ), simply taking the outer direct sum of two modules should do just fine to give you a categorical coproduct.
So what is going on, can anyone point out the difference between coproduct and free product. What am I doing wrong?
This confusion has led me to believe than 'eight' or an 'infinity symbol' has fundamental (homopoty) group}.
Thanks, Evilbu 14:53, 4 June 2006 (UTC)
But that is bad for me! So you are saying : free product of two groups is NOT the same as coproduct?
Evilbu
17:05, 4 June 2006 (UTC)
Oh yes, I see, I think I have made a serious mistake in assuming something. I was seeing the abelian groups as a subcategory of the group category. I cannot take some abelian groups, take the free product (defined in the categorical sense) and assume it will still be that in the bigger category right? Evilbu 20:58, 4 June 2006 (UTC)
I know how easy it is to fall off a bike while not moving - I also know that it's harder to turn the wheel when I am in motion. I've had a look at angular momentum and related topics and I can't figure why a rotating bike wheel is harder to turn from its line of motion than a stationery one. Any help please? Anand 18:54, 4 June 2006 (UTC)
I just started this article. If anyone believes they can add anything more to it, even one more sentence, go right ahead. — BRIAN 0918 • 2006-06-05 05:52
A question about poles. Consider a function of this form:
Will it have a pole at z = a? A removeable singularity? Or some other form of oddness?
Maelin
06:26, 5 June 2006 (UTC)
Several of my measuring tapes have a measure mark that is a small black diamond shape. There are five of them for every eight feet or 19 1/5 inches for each mark. What is this measure? Sincerely
Its purpose is to allow carpenters to divide 8 feet exactly in five. See this page and this page (scroll down to diamond) for documentation. There has been a dispute on the Wikipedia where a user claimed it to be an "English cubit", but this is apparently not correct. -- vibo56 09:45, 5 June 2006 (UTC)
So the black diamond is a carpenter's mark! Very interesting, I'd been supposing it was some foreign unit of measurement. I was guessing Chinese!
Thanks very much. Albert J. hoch Jr.
What does the following integral evaluate to:
where is the Dirac delta function and H(x) is the Heaviside step function.
What about the following:
If these do not exist, what are reasonable approximations to them I can make? deeptrivia ( talk) 18:27, 5 June 2006 (UTC)
Thanks lethe. Is it terribly unsafe to assume, for engineering purposes, that H(0) = 0.5, while integrating these? deeptrivia ( talk) 21:42, 5 June 2006 (UTC)
it gives:
The limit of this expression as epsilon --> 0 is undefined. However, as an engineering approximation, we can assume to be something small, like 1e-24, and then and , and so the integral evaluates to 1. Is there any flaw in this reasoning? I'm asking because there's a significant thing happening between -1e-24 and 1e-24, which will be ignored by this assumption. Another thing is, if I were doing this integration from, say -1 to 1, then, say you pointed out I won't have cared about values at finite points. But here, the integration has to be done in a range that encloses 0 and is as small as can be imagined, so the value at 0 might have a significant effect. Regards, deeptrivia ( talk) 01:14, 6 June 2006 (UTC)
The limit of
as epsilon --> 0 is undefined according to Maple itself (using the 'limit' function). The first approach I followed was the one proposed by Jitse Niesen, but I can't remember any more why I gave up on it. Anyway, these equation arise from a nonlinear treatment of point loads and moments at various points on a flexible beam with discontinuities in cross sectional area (like a stepped beam.) I am using heaviside functions to model steps in areas, and dirac functions to model point loads and moments. Any suggestions appropriate to this situation? Thanks. deeptrivia ( talk) 04:18, 6 June 2006 (UTC)
If you use the definition of the Riemann-Stieltjes integral, then the first integral is equivalent to
On the other hand, . Conscious 05:57, 6 June 2006 (UTC)
Hi,
consider a cylinder thus
I am still working on that torus, and I thought, this would be handy :
suppose I have a loop ,so let's say a path
and another , a path
Are these two loops in the same homology class, I mean, is their difference, in an element of the image of
-- Evilbu 20:01, 5 June 2006 (UTC)
Thanks, yet I'm sorry but I don't completely get it.
Please be very clear in what you mean : homotopy between paths, or homotopy between continuous maps in general.
Here was my idea : a 'push up u' of (b-a) is a continuous map from the cylinder to the cylinder, homotopic with the identity
this means
and thus
A little weird I think. Why would a homotopy between those two points suffice? And what kind of homotopy do you speak, usually they mean with 'homotopy between two paths' : the homotopy fixes begin and end point all the time, which cannot be the case here as both are even disjoint.
Evilbu
21:42, 5 June 2006 (UTC)
Thanks everyone, it's a bit hard to understand that all completely. But I surely would like to know this : lethe, you wrote that p-q is the boundary of a segment. But I was taught that you need linear combinations (over the integers) of 2-simplices (those are maps from a triangle in the plane to your space). How would you proceed? Evilbu 08:15, 6 June 2006 (UTC)
tl | T | tr | ||||
● | ⟵ | ● | ||||
L | ↓ | ↘ | ↑ | R | ||
● | ⟶ | ● | ||||
bl | B | br |
T = (tr, tl) | B = (bl, br) | L = (tl, bl) | R = (br, tr) | D = (tl, br) |
∂T = tl − tr | ∂B = br − bl | ∂L = bl − tl | ∂R = tr − br | ∂D = br − tl |
∂σ1 = D + R + T | ∂σ2 = L + B − D | ||||||||
|
|
∂σ1 = D − L + T | ∂σ2 = L + B − D |
∂(σ1+σ2) = T + B |
There is a highly useful formula which looks like the sine rule, ie something/something = something/something = something/something but I've completely forgot it. I believe terms like arc length, area, theta etc were included in it but I can't remember the other ones, nor can I remember the order. Thanks, Matt. —Preceding unsigned comment added by 80.229.237.12 ( talk • contribs) 19:39, 5 June 2006
What the article didn't mention(can anyone expand the radian article?) is however the formula of sector area in radian terms. Since the area ratio between the sector and the full circle is the same as the ratio between their radian measures, we have
I'm trying to implement IDEA in assembly language on a 386, and I'm having trouble because it was optimized for 16-bit processors. I want to be able to concatenate two 16-bit numbers to multiply mod and then separate them later, but I'm having trouble with it. I've tried using and but neither lets me extract just the multiplications I want and it's all mixed up. -- Zemyla t 21:05, 5 June 2006 (UTC)
I assure you this is not homework, just a question from someone who hasn't taken geometry since high school and did almost nothing with three dimensional shapes, at that.
Let's say I have a truncated icosahedron that should fit into a sphere an inner diameter of 150 cm. How long should each of the vertices be? I'm sure this is probably easy for someone to calculate given all of those wonderful symbols on the icosahedron page but I'm totally baffled by them.
Many thanks. -- Fastfission 22:48, 5 June 2006 (UTC)
I have to do some cutting and splicing of audio files in WAV format, but I don't seem to have suitable software handy. Does anyone know of any freeware which might do the job and run under Windows XP? —Preceding unsigned comment added by Physchim62 ( talk • contribs) 19:00, 6 June 2006
After i have played around with the number 9 i noticed that 9 will always end up as 9.
For example:
9x9 = 81 (8 and 1) 8+1=9
9x15 = 135 (1 and 3 and 5) 1+3+5=9
9x265 = 2385 (2 and 3 and 8 and 5) 2+3+8+5=18 (1 and 8) 1+8=9
9x996633 = 8969697 (8 and 9 and 6 and 9 and 6 and 9 and 7) 8+9+6+9+6+9+7=54 (5 and 4) 5+4=9
This you can do with any random number. 9x? = 9
So my question is: When was this noticed the first time and who noticed it?
-Randi Hermansen, Denmark
Does any one have any information on how the vast tables of logarithms were calculated. Clearly, it is not a simple task or tables would not have been necessary. 68.6.85.167 21:52, 29 May 2006 (UTC)
I just wanted to say thanks to all of the contributors here. The people here are really knowledgable and have help satiate my intellectual curosity on different occasions. Mayor Westfall 20:21, 6 June 2006 (UTC)
I'm learning recurrence relations in school and I frequently come across problems involving finding the number of generations needed for the recurrence relation to have an answer twice its original value. So basically we are asked to find n when:
The method that is taught in school is to go through each generation by iteration and eventually finding n when you find that un has grown to twice the size of u0. However, the obviously easier method is to use the equation:
Is there a similar shortcut when the recurrence relation is instead defined as this?:
I have tried working it out by firstly expanding each iteration:
From this the whole series can be expressed as:
We can see the bracketed part of the equation is actually a geometric series, with the starting value b, ratio a and number of terms n (not n−1 as the starting value counts as one term). Also, the number of terms appearing in the geometric series seems to equal the number of iterations in the recurrence relation. Therefore we can use the equation for the sum of the geometric series:
Where s is the starting term, r is the ratio and n is the number of terms. Thus, substituting into the recurrence relation:
Unfortunately at this point I hit a dead end because I'm unable to change the subject to n. Is this along the right lines or is there a completely different method? ----
★Ukdragon37★
talk
20:27, 6 June 2006 (UTC)
hello, i'm a student of physics taking an engineering course. can anyone give some intuition on the following:
the fourier transform of a sine wave of frequency w extracts the frequency w. but a fourier transform of a delta function (which has no width (in the time domain) and so no duration) extracts all frequencies.
my question is, how can a delta function accommodate all frequencies?
thanks -crj
ha! it makes sense that higher frequencies are needed to produce more abrupt transitions. thank you all for taking the time to answer. (incidentally, not sure how the answer sech(1⁄A ω√π⁄2) was obtained. i searched through my signal analysis books, an engineering mathematical handbook, and a book on mathematical methods of physics but could not find the result. i even tried to get this result using Maple, but all i get in return is my original input!)
Apple has released
Boot Camp public Beta, which will be included in
Mac OS X v10.5.
Question: Will
Windows Vista also be able to run in a Mac usinq Boot Camp? --
Alexignatiou
08:49, 7 June 2006 (UTC)
Hello,
I am quite unsure about something my professor told me.
Let be open, and let f be a function in , unless I am really mistaking, that just means that f is defined in , and that is can be continuously derived p times
Now he told me if I just define an extension by making it zero outside \Omega , I get an function, locally integrable thus : integrable over every compactum.
Either I got my definitions incorrect, or this is incorrect : what about in ?
Evilbu 10:14, 7 June 2006 (UTC)
Hm, I don't understand, is that true? What about and That function can be extended to a function, but it certainly will never be integrable?? So what is your definition in your opinion? I am guessing you would go for this then :
and and f can be derived continuously p times
Evilbu 17:10, 7 June 2006 (UTC)
Thanks, but then what is your definition exactly of ? Evilbu 19:52, 7 June 2006 (UTC)
If I install Ubuntu (64-bit linux) on my computer with AMD64 3200+ should I expect an increase in performance? -- Username132 ( talk) 13:22, 7 June 2006 (UTC)
I don't want to pay for hardware capable of more than I need. I want to buy a new system disk and the way I see it, I've a few options; a) buy two WD raptors and put into RAID-0 configuration b) buy two budget HDs and put into RAID-0 c) buy one raptor d) buy one budget drive
When loading the OS for example, is the speed of the HD a bottleneck for an AMD64 3200+ system with Corsair value RAM? And what games really benefit from 300 Mb/s data transfer to and from your HD? I would have thought the graphics card would be the bottleneck in any system with an old ATA-100 - I mean most important, immediately required information will be in the RAM, wont it? —The preceding unsigned comment was added by Username132 ( talk • contribs) .
If I roll three six-sided dice (3d6) and only take the median roll (not the mean or average), what kind of bell curve or distribution odds would it give me for the result 1 to 6?
If I roll two 20-sided dice (2d20) and only look at the higher result of the two, what is the average result I will get? What about 3d20 and only look at the highest die? 4d20 etc. up to 16d20...?-- Sonjaaa 11:43, 8 June 2006 (UTC)
1 : 2/27 2 : 5/27 3 : 13/54 4 : 13/54 5 : 5/27 6 : 2/27
It is quite straightforward to use JavaScript to return today's date, but how would you go about getting it to return tomorrow's date, or the date in ten days' time? — Gareth Hughes 14:18, 8 June 2006 (UTC)
Not long ago I purchased an "Introductory" copy of Microsoft's Visual C++ on eBay. Since I have not programed in C since 1984 I was really surprised at how far it looked like C had come. However the "Introductory" version will not compile programs that worked great back in 1984 and even when a console program is written that compiles with no errors it stops and says that because it is an "Introductory" version that I can't make an execute file. I need another compiler but would like to avoid giving away any more of my hard earned money to Microsoft. What C++ compiler do you recommend? ... IMHO ( Talk) 17:12, 8 June 2006 (UTC)
... IMHO ( Talk) 20:42, 8 June 2006 (UTC)
I have a very strange problem with Matlab's bvp4c. Hopefully, someone here would have some idea what's going wrong. I am solving a 30-variable boundary value problem, and I know that for certain inputs, a particular variable u3 must be 0 everywhere. bvp4c returns the values of variables y(x), as well as their derivatives yp(x). The derivative of u3 in the result is always zero (sth like 1e-17 to be precise, and x ranges from 0 to 1), so that looks good. But the value of u3 is varying a lot (instead of staying 0, it goes smoothly, but not linearly to 0.9). Doesn't it clearly mean there's a bug in matlab's bvp4c? What else could be the problem? deeptrivia ( talk) 18:10, 8 June 2006 (UTC)
Suppose we have a large symmetric matrix which can be partitioned into smaller blocks matricies. These smaller blocks happen to be symmetric too. Suppose further, that we are given all the eigenvalues of each of these blocks. Is there a way to infer the eigenvalues of the entire original matrix easily? -- HappyCamper 19:09, 8 June 2006 (UTC)
this is somewhat elementary, and perhaps you know this already. but in the special case that all your blocks are scalar multiples of each other, then it is a Kronecker product and you can get the eigenvalues of the big matrix. Mct mht 00:39, 15 June 2006 (UTC)
Has there been any research done into extending taxicab geometry into 3D space? -- Tuvwxyz 21:11, 9 June 2006 (UTC)
My stepdad ( a landscaper) recently asked me how to find the area of... I guess the best way to name it is a sector of a oval. There are to radii (?) that meet at a right angle and one is 10 feet and the other 8 feet. They are connected by an arc that is ≈17 feet. How would I go about finding the area of this shape? Thanks. schyler 01:43, 10 June 2006 (UTC)
I tryed to translate the Mathematica .nb-files to TEX- and Mathmarkup- files. Wikipedia did not understand these. The only way was to translate to HTML. It consisted of mainly .gif images, which i had to translate to .png using GIMP . If i used small fonts they were unreadable. I think this is my only article, Collocation polynomial,so i am not interested to become spesialist in TEX or mathmarkup. Now i am going to holiday. If someone has time and possibility to cleanup the article, please do. -- penman 05:08, 10 June 2006 (UTC)
Yes, this is assignment work, but I have done most of the work. We are given the equation of the basic hyperbola x^2/a^2 + y^2/b^2 = 1, and are asked to prove that PF' - PF = 2a, where P(x,y) is a variable point on the hyperbola, and F' and F are the foci at (-c,0) and (c,0) respectively. I can prove this by taking the basic equation above, and manipulating it to show sqrt((x+c)^2+y^2) - sqrt((x-c)^2+y^2) = 2a. However, I find I need to substitute c^2-a^2 for b^2 in order to do this. In other words, I need to prove c^2 = a^2 + b^2. Looking around on the internet, because most people start with the difference of the distances (sqrt((x+c)^2+y^2) - sqrt((x-c)^2+y^2) = 2a) and use that to find x^2/a^2 + y^2/b^2 = 1, they simply define b as being sqrt(c^2-a^2). Obviously, since I am working from the base equation and using it to find the difference of the distances, it would not be right to just replace b^2 with c^2-a^2 without providing justification. Can it be done? Or is my method too complicated?
Hi there,
Working on a publication using a lot of information burned onto a DVD by a friend of mine. But I keep getting cyclic redundancy checks. The article here is rather useful (but rather hefty)... what I need to know, though, is if there's a way to say "just skip that bit and keep copying, please" to the computer. If it's just a little little bit of data that the computer can't read, can't I just hop over that bit and see if the file's still basically okay later? If one pixel of one photo is FUBAR, that doesn't change that much for me. -- MattShepherd 12:20, 10 June 2006 (UTC)
dd conv=sync,noerror
. However, you may still end up losing entire disk blocks (a couple of kilobytes) for even minor scratches. It's the best solution I know of, though. —
Ilmari Karonen (
talk)
00:05, 11 June 2006 (UTC)
dd conv=sync,noerror
, though the page suggests that it may be somewhat faster in certain situations. —
Ilmari Karonen (
talk)
13:41, 11 June 2006 (UTC)coe=3
setting — except that the feature is apparently not supported by CD/DVD drives. —
Ilmari Karonen (
talk)
13:50, 11 June 2006 (UTC)
Suppose F is a set, is a binary relation on F, and for each a ∈ F there is b ∈ F such that (a, b) ∈ R. I am interested in recursively constructing a sequence (ai)i ≥ 0 such that for every non-negative integer i, (ai, ai+1) ∈ R. It is easy to show that finite sequences of this type with arbitrary length exist; However, I am having difficulties showing that an infinite sequence of this type exists. That is, of course, unless I am using the axiom of choice, in which case the proof seems straightforward. My question is, is the possibility of this construction provable with ZF, or is the axiom of choice (or a weaker form) necessary? Is it still necessary if it is also known that F is countable? I strongly believe that the answers are, respectively, yes and no, but I just want to make sure. -- Meni Rosenfeld ( talk) 17:37, 10 June 2006 (UTC)
Great, thanks! -- Meni Rosenfeld ( talk) 19:18, 10 June 2006 (UTC)
Hi,
let be open and nonvoid in
let
by that I mean and on every compactum it is integrable
suppose now that for every
(this means w is infinitely differentiable on all of but it has a compact support in )
show that f is almost everywhere zero
Now I have worked on this, and came up with the idea of convolving with an approximation of unity.
But then I got confused, what exactly to do with this open I have to respect the confinements of my domain right? Thanks,
Evilbu 19:56, 10 June 2006 (UTC)
Yes I see what you mean, but if f was continouos and nonzero at some point p, it could make it strictly positive or negative in an open ball around it, and then a proper w can quite easily be found, but what to do here, a set with positive measure, so many cases? Evilbu 08:52, 11 June 2006 (UTC)
Well I'll be honest, it's a proof from a syllabus that me and my costudents dispute. The proof works with convolving, but seems to show little regard for necessary analytic subtleties (like discontinuity even). Evilbu 17:00, 11 June 2006 (UTC)
I need to create an array that can hold 10 million integer numbers and fill it with random numbers ranging from 1 million to 10 million (minus one), When it is filled I need to write the index and contents to a file. I know how to generate random numbers in MASM and how to write from memory to a file using debug but I need to put them together in a MASM program. Anyone have a demo or example? ... IMHO ( Talk) 00:52, 11 June 2006 (UTC)
Yes this information helps. Thanks. However, my goal in part here is to learn (or relearn) MASM. Back in the late '60's and early '70's assembly language was quit straight forward (and can still be that straight forward using the command line DEBUG command). Where I am having trouble currently is with INCLUDEs. Irvine32.inc in particular so I am trying to avoid even the use of INCLUDEs and do this (if possible) using only a DEBUG script. Don't get me wrong I have spent ALL of my programming career writing in high level language simply so that I could get far more work done but now my goal is to go back through some of the programs I have written in a high level language like Visual Basic and convert what ever I can to concise assembler or machine code which might help bridge the gap between Windows and Linux whereas a program written in C++ for Linux (source code) may otherwise find difficulty (after it is compiled under any version of Window's C++) to run. What I need specifically is to 1.) know how to create and expand a single dimension integer array with the above size. Therefore I need help with both the memory management and indexing, 2.) Although I can make random numbers fall into any range in Visual Basic I'm not sure about doing this in assembler, 3.) I also need help in writing the array contents and index to a file since even though I know how to write something at a particular location in memory to a file using DEBUG and how to write an array to a file using Visual Basic it has been a long, long time since I used assembler way back in the early '70's. Your suggestion to try writing in C and then doing a compile to study the output is a good and logical one but my thinking is that by the time I get back into C so that I can write such a snippet of a program that I could have already learned how to do it using MASM. Even still it is not an unreasonable or bad idea. Any code examples would lend to my effort and be appreciated. Thanks. ... IMHO ( Talk) 14:58, 11 June 2006 (UTC)
I followed your suggestion to look at the disassembled output of the following C++ code and was shocked to find that while the .exe file was only 155,000 bytes the disassembled listing is over 3 million bytes long.
#include <stdio.h> #include <stdlib.h> main() { printf("RAND_MAX = %u\n", RAND_MAX); }
I think I need to stick with the original plan. ... IMHO ( Talk) 15:43, 11 June 2006 (UTC)
E:\src\wikipedia\masm_test>cl /Fa /c /I "c:\Programfiler\Microsoft Visual Studio\VC98\Include" main.c Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 Copyright (C) Microsoft Corp 1984-1998. All rights reserved. main.c E:\src\wikipedia\masm_test>dir *.asm Volumet i stasjon E er ARBEID Volumserienummeret er 4293-94FF Innhold i E:\src\wikipedia\masm_test 13.06.2006 19:23 2 292 main.asm
Okay, finally got it! The thing that was messing up the command line compile under VC++ v6 Intro seems to have been a "using namespace std;" line (although oddly enough it has to be removed when the contents of an array variable are incremented but required when the same variable is only assigned a value). It looks like VC++ Express 2005 has the same settings function in the GUI but I have not yet been able to figure out and follow the procedure to get it to work. Its command line .asm intruction might also work now but I do not have time right now to test it. Thanks for all of the detailed suggestions and for helping to make the Wikipedia more than I ever dreamed it would be. Thanks. ... IMHO ( Talk) 21:35, 15 June 2006 (UTC)
what is html???
how would i do these problems, i have an exam tomorrow and i would love an answer soon:
b. x/(2x+7)=(x-5)/(x+1) and c. [(x-1)/(x+1)]-[2x/(x-1)]=-1
i have no idea how to approach this problem the directions say: Solve each equation. -- Boyofsteel999 01:09, 12 June 2006 (UTC)
1. Multiply by the terms on the denominator (ie. the bottom). For example, if you had the equation you multiply by the and terms, giving you .
2. Solve the problem as you would any kind of quadration equation - gather it into a normal quadratic form, and either factorise or use the quadratic formula. In this case, we first get , which reduces to , the solutions of which (using the quadratic formula) are .
Technically there's a third step - make sure that the solutions you get are not going to make the denominators zero - but a. this shouldn't happen anyway, and b. once you get to complex analysis you treat these solutions that aren't really solutions as solutions that just aren't explained clearly. Confusing Manifestation 02:15, 12 June 2006 (UTC)
The inverse limit of the cyclic groups Z/pnZ for p a prime gives you the group of p-adic integers (a group about which I know little). It seems to me that the collection of all finite cyclic groups also forms a direct system of groups over the directed set of natural numbers ordered (dually) by divisibility. Thus shouldn't there be an inverse limit of this system as well? What is it? Probably it's just Z, right? - lethe talk + 06:10, 12 June 2006 (UTC)
4 | 8 | 12 | 16 | 20 | 24 | 28 | 32 | 36 | 40 | 44 | 48 | ... |
1 | 1 | 9 | 1 | 5 | 9 | 21 | 1 | 9 | 25 | 33 | 33 | ... |
In sentential logic, it seems to me that the set of well-formed formulas (wffs) may profitably be thought of as a set with an algebraic structure. One has a set of sentence variables, and one may perform various operations on the sentence variables; usually disjunction, conjunction, negation, and implication. The sets is then some sort of free algebraic structure in these operations on the set of sentence symbols. Another algebraic structure with these operations is the set {0,1} (with the obvious definitions of the operations), and a truth assignment may then be defined as a homomorphism of this kind of structure from the free structure of wffs to {0,1}, which is used to determine an equivalence relation called tautology. The Lindenbaum algebra is the quotient of this free structure by this equivalence relation and is a Boolean algebra.
This description in terms of algebraic language differs in flavor a bit from the way I was taught mathematical logic (from Enderton), and I have some questions. It seems that this algebraic structure is completely free; it doesn't satisfy any axioms. So I guess it's not a very interesting structure. Is this a standard construction? Does it have a name? I've been using the name "free pre-Boolean algebra", so that a truth assignment is pre-Boolean algebra homomorphism.
I like the algebraic description here, one reason being that it gives a concise way of defining semantic entailment. On the other hand, I don't see any nice algebraic way of describing syntactical entailment. Is there one? Can I describe modus ponens as an algebraic operation in this structure? - lethe talk + 06:10, 12 June 2006 (UTC)
First I would like to state that this is not for homework purposes, merely some discrepancy with a textbook we discovered recently. We've experimented with combining cubes in a variety of completely different formations (that is, excluding replicas via reflection or any other direct transformation), and the particular one we decided to do on that occasion was 4. However while we could find only seven different combinations, the textbook insisted that there was eight. Can anyone help me to either confirm the textbook answer, or our own answer, and if possible state a brief "proof" of why a certain answer is so.
Also, the reason that we were experimenting was because we were trying to develop a general algebraic processes to find the number of combinations as a function of the number of identical cubes. If anyone can possibly give any directions towards this search at all it would also be helpful and greatly appreciated. LCS
I saw a question on the science page that bugged me and made me think of the following quesiton:
Say you have two moths flying toward each other carrying a light source. They are attracted to light 10 meters away, and their parallel paths are separated by 5 m, would they crash into each other? ...Sounds like this would make a good text book calculus question. Anyone have an answer? XM 16:50, 12 June 2006 (UTC)
Once they detect the light, they are pulled towards the light at the same speed they are traveling--(XM) but too lazy to sign in.
I am making an applet at a certain point in this applet i clear a JPanel with the removeAll(), after i have done this it seems as thought it is impossible to add anything to this JPanel again.
Is it possible to add to a JPanel after having used removeAll(), or how would i go about placing new content to the same JPanel while taking off the content thats already there Thank you very much
-- 70.28.2.95 19:37, 12 June 2006 (UTC)
I tried using validate() but it still wont update, the JPanel stays blank. I tried invoking it both before and after adding to my JPanel but the results were the same -- 70.28.2.95 00:47, 13 June 2006 (UTC)
validating the parent container and all the components seems to have done the trick. Thanks alot for your time. -- 70.28.2.95 19:00, 13 June 2006 (UTC)
For the WikiGeometers out there...I wonder if you could help me identify these two solids by name? I'd like to include them in articles which might be lacking in illustrative images...Thanks! -- HappyCamper 21:42, 12 June 2006 (UTC)
The one on the left is impossible to make unless you are talking about spherical geometry. As for the one on the right, I have no idea. Yanwen 00:21, 14 June 2006 (UTC)
I would like to say thanks to the editors of this project. I have learned more in a few weeks of perusing the portals in the math section than I did all through my engineering curriculum. Absolutely fascinating stuff, and very well organized. In my mind, mathematics is learned best by a first organizing the general ideas of math, then discovering how they are sometimes connected. This thorough organization has been a hugely interesting, and, I suspect, many others who just read but don't say anything. Anyway, sometimes simple thanks justifies long hours of effort, I've found. I hope it does for all of you. Denmen 02:33, 13 June 2006 (UTC)
How can a person measure the height of a tall object such as a telephone pole, a tree, a tall building, etc? —Preceding unsigned comment added by Stockard ( talk • contribs) 20:08, 12 June 2006 (UTC)
Can someone tell me what ΔQ% means? Groc 10:39, 13 June 2006 (UTC)
I have a set of N points (xi,yi). I want to find out the radius and subtended angle of the circular arc that can best approximate those points and the least square error in this approximation. How can I do this? Thanks. deeptrivia ( talk) 19:47, 13 June 2006 (UTC)
I've been fiddling around with primes for a bit, and I found a property that I've never heard of before. I'd like to know if it already exists, or if I'm the first to find it. Given a prime P, the product of all primes less than P is A. If a prime N<A can be found that is close to A (meaning A-N<P2), there is a corresponding prime number at A-N. Of course, this can't break any records, since it looks down for primes instead of up, and can only find new primes between P and P2, and then only if there happens to be a prime known between A and A-P2, but still. Anyone heard of it? Black Carrot 22:48, 13 June 2006 (UTC)
I don't think I want to bet, but I'm curious about the way the odds work. Currently at an online betting site, the odds for the first five teams are:
Brazil 4.1 England 8.4 Argentina 8.6 Germany 9.6 Italy 12
Lets say I were to place my bets so I placed $1 on Brazil and $.50 on each of the other four. Am I right in thinking I'm guaranteed to win something if any of the first five win? Likewise, would there be some way to pick my amounts so I'm guaranteed to win something if any of the first ten win? Finally, am I right in thinking that statistically, even doing this, my expected wins should be zero overall (if the odds are fair and accurate), as the pennies I win when the top teams win would be exactly balanced out by the dollars I'd lose when one of the underdogs won? (obviously there are also fees to pay, I assume, but I'm not counting that). — Asbestos | Talk (RFC) 14:01, 14 June 2006 (UTC)
If x is lognormal distributed how is s=s0*exp(x) distributed?
A first-year maths lecturer last year gave us a delightful little insight into where our progressively less intuitive number sets come from. We start with the positive integers, the normal, every day counting numbers. But then we have no solution x for equations like 1 + x = 1. So we need another number, and enter stage left, zero. But we still have no solution for equations like 3 + x = 2. So we need more numbers, and lo, the negative integers give us the complete set of integers. But now we have no solution for equations like 2 * x = 1, and again, we need more numbers, so we get the rationals. Then equations like x * x = 2 yield the irrationals (giving us the set of reals) and if we expand our number set one more time to solve x * x = -1, here we are finally with the complex numbers.
But is that as far as we need to go? Are there any equations like this that we still can't solve, that lead us to extending our number set yet further? Is this where quaternions, octernions et al become needed (I've not read much on them, I admit) , or are they just useful extensions of the concept of complex numbers that have nifty results for physicists? I've played with complex numbers idly while thinking about this but I can't think of any problems left. Are complex numbers finally the end? - Maelin 15:26, 14 June 2006 (UTC)
hello, i hope i am looking in the right section. what is archetypal systems analysis? also i found it as archetypal social systems analysis. thank you very much for you time. -- Marina s 19:12, 14 June 2006 (UTC)
Recently I had the idea of somehow creating a shell extension similar to Microsoft's . ZIP CompressedFolder extension that would enable users to browse through a game archive file. It would handle the game archive files almost the same way as . ZIP files are handled (with shell menu items and being able to open the file and browse through as though it were a folder). Is this possible? If so, how would I go about doing it? What language would be best for this project? I know C#, some C++, and Visual Basic.
Any help, comments, or input on this would be greatly appreciated.
-- Kasimov 19:14, 14 June 2006 (UTC)
It's the Halo/Halo 2 .map format. -- Kasimov 12:21, 15 June 2006 (UTC)
Alright, I don't know if this is enough information but here's some that could be helpful:
The file itself is divided into 4 major sections:
Header |
BSP(s) |
Raw Data |
Tag Index and Meta |
The header is uncompressed and is always 2048 bytes. However, the rest of the file is zip compressed with zLib.
Now, I figured since it's compressed with zlib that would make it easier to make a shell extension, right?
I hope that's enough information, because really it would be pointless for me to type here the entire structure of the file. If you're looking for a complete breakdown of it then visit these two pages: Page #1 Page #2.
Thanks -- Kasimov 13:37, 15 June 2006 (UTC)
Last night a friend and I got into a dispute. In a multi-choice exam with 4 choices (e.g A/B/C/D), where the answers are randomly selected among the 4 possibilities (so for any one question, a random guess at the answer has a 0.25 chance of being correct), what is the best strategy if you have to guess at an answer?
She said that sticking with one letter (e.g. Always guess "A") gives a 0.25 chance of getting the right answer, BUT that choosing at random between two letters (e.g. random guess between "A" or "B") gives a 0.125 (1/8) chance of being right instead of 1/4. Her reasoning: First there is a 0.5 choice between A and B, and then a 0.25 chance of being right. 0.25*0.5=0.125.
I'm sure that's only correct if the real answer is always the same letter.
I think that regardless of whether you guess randomly between A - D, or any two choices, or stick with just one, your chances of being right approach 0.25 in all 3 cases. Because of you always choose A, on average the answer will be A 25% of the time. If you guess randomly between say, A and B, on average each letter will be right 12.5% of the time, and 12.5+12.5=25% (because while A is correct 25% of the time, by choosing between 2 letters the number of A's chosen has been halved. Of course, this also applys to the choice of B, thus the total proportion of right answers is still 25%). Increase the guess to between ABC and D, we get 6.25*4=25%.
Who is correct here?-- inks T 00:28, 15 June 2006 (UTC)
I'm off to college this fall, to major in Computer Science. I thought it would probably be a good idea to get a laptop, so, hearing that ThinkPad hardware is well-supported by Linux, I bought a very nice ThinkPad. I want to dual-boot windows and linux.
I've looked into Linux in the past (and even tried to install Slackware, though I was unable to resize my Windows partition so I gave up) and I've decided on SUSE Linux, primarily because of the easy setup (especially in partitioning) and the focus on ease-of-use.
I have three questions:
1) Which desktop envoronment should I choose, KDE or Gnome? I've had a pretty good experience with KDE trying out Knoppix, but I want to know if I'm really missing out on good stuff in Gnome. Can someone give me a comparison feature-by-feature of what they like about each? Which is used in this video?
2) Will YaST automatically configure my boot menu to dual-boot with windows if it detects OEM Windows XP installed, or am I just going to be stuck with Linux until I can figure out LILO or GRUB?
3) When I upgrade to Vista this fall, will there be any problem getting it to stay in the Windows partition and keeping it from taking over the whole hard drive when it installs? Will I have to rewrite the boot settings, or will Vista do this for me? Or will it rewrite the entire record and take out Linux? In that case, how do I modify it from within Vista to allow access to Linux again?
-- Froth 01:46, 15 June 2006 (UTC)
taxonomy of real numbers
In Mozilla Firefox, is it possible to install the DOM inspector after you've already installed the browser earlier without it? I didn't install DOM inspector because I thought I wouldn't need it, but now it looks like I do, and would like to avoid completely reinstalling and losing bookmarks, extensions and history info in the process. - 131.211.210.12 11:59, 15 June 2006 (UTC)
Me and all my friends cannot get this one. It seems easy enough but there's always a part where we can't get any further..
2x = (x+1)(ln10)/lne
What is x???? —Preceding unsigned comment added by Gelo3 ( talk • contribs) 13:07, 2006 June 15
This ISN'T homework, so PLEASE stop making assumptions. This was a question from a past exam paper I found on the internet for study. 220.239.228.252 14:43, 15 June 2006 (UTC)
Read this :
http://en.wikipedia.org/wiki/Logarithm#Other_notations
Evilbu
15:44, 15 June 2006 (UTC)
I am feeling very daft, as I can't seem to figure this one out and I hope that someone smarter (and more awake!) than me will be able to help.
I scanned in a photo using my scanner, it returned a 150kB file. All well and good. I open it (in Paintshop, if that makes a difference), find out it's sideways, rotate it 90°, save and close. Imagine my surprise when the same file is now suddenly 750kB! What in the world is going on - I just rotated the image, surely it contains the same amount of information?
My guess (after much reading through JPG) is that my scanner is sending me a JPG which is already compressed somewhat, but when Paintshop saves it at 'no compression' the filesize obviously increases. Does this make sense? Or do you suspect something else may be at work?
Thanks in advance! — Quantum Eleven 14:09, 15 June 2006 (UTC)
Hello,
I am studying tensor products and I think it would really be useful to think about this problem in general
let M be a right R module, and N a left R module
Now let us assume nothing about the ring (commutativity, division ring,...)
now consider and an element in it of form
Now when is
I know just saying "one of them must be zero at least" is simply not true, at least when I am working with non-divisionrings... But then what is the criterion?
Could this be it : one of them must be "divisible" by an element in the ring R such that the other one, multiplied with it, gives zero?
Thanks,
Evilbu
14:16, 15 June 2006 (UTC)
Thanks. So what do you think? This criterion is not correct? I stress again that the ring (apart from having unity) can be as free as it pleases in all it weirdness, and so can the modules. Nobody seems to be comfortable answering this question. I studied constructing tensor products (with balanced products and all) , which eventually implied taking a quotient (which is a result of the relations) of a free abelian group. So an element in the big free abelian group gives zero in the quotient if it is a finite sum of several elements given by those relations ( I am taking of elements like ~. There can really be millions of terms in a sum like that, so I don't see proving a criterion in this way can ever be done?
Anyway, as always, I stress my gratitude for the kind, quick and to the point I help I receive from this wonderful site.
Evilbu
14:25, 16 June 2006 (UTC)
If one holds a piece of string between two points on a sphere, the string would be tracing the arc/curvature/perimeter/circumference——i.e., "great circle"——segment between the two points, which would equal the central angle, . To find the distance between the two points you would multiply the central angle by the sphere's radius, as the radius equals the radius of the circumference. With an ellipsoid, however, the radius of the body and the radius of its circumference is different. You have two principal curvatures, (north-south,east-west), and their corresponding radii,
. Curvature in a given geodetic direction, , is given as
. The corresponding radius of curvature ("in the normal section") is then given as
. But, if you take a minuscule distance (i.e., ≈ 0), then
not ! There was a stub for
arc recently created. Would the second equation, equaling , be the "radius of arc", thus the equation of arc would be ?
If you divide any north-south distance by it equals the average value of M within that segment, and a minuscule east-west distance (since, except along the equator, east-west along a geodesic only exists at a single point——the transverse equator) equals N. So what is a minuscule distance, in a given geodetic direction, divided by , a radius of? Curvature? Arc? Perimeter? If I Google "arc" or "radius of arc" (or even "degree of arc"), all I find are simplistic spherical contexts, nothing elliptical, involving M and N! P=(
I understand basic, concrete geodetic theory (besides ellipticity, there is curvature shift towards the pole as the geodetic line grows, culminating in a complete shift to north-south for an antipodal distance, since north-south is the shortest path), so I know you can't simply take the spherical delineation, average all of the radii of curvature/arc along the segment and multiply it by to get the true geodetic distance (though, the difference does seem directly proportional to the polar shift involved——i.e., the smaller the distance, the closer this "parageodetic" distance is to the true geodetic one!). But I digress... P=)
~Kaimbridge~
17:20, 15 June 2006 (UTC)
I am currently making a program to generate a random name using United States Census data and Markov chains. However, I want to have a little more flexibility in the process. So I want to be able to make a bridge between a given beginning, some given middle letters, and a given ending, so I can generate a name like Mil???r?a. Currently, I am using a three-letter window. Does anyone know how to generate this bridge? -- Zemyla t 21:35, 15 June 2006 (UTC)
There is a certain word puzzle, that I have heard many times before. I have searched for said puzzle, but cannot seem to find it anywhere. I was wondering how the math works out this way in this puzzle:
Three men go to a motel and rent a room. The deskman charges them $30 for the room. The manager of the motel comes in and says that the deskman has charged them too much, that it should only be $25.
The manager then goes to the cash drawer and gets five $1.00 bills, and has the bellboy take the money back to the three men. On his way up to the room, the bellboy decides to give each of the men only one dollar apiece back and keep the other two dollars for himself.
Now that each one of the men has received one dollar back this means that they only paid $9.00 apiece for the room. So three times the $9.00 is 27.00 plus the $2.00 the bellboy kept comes to $29. Where is the other dollar?
Why does it come out to $29 and not $30? I always suspected that it was because you cant multiply the remaining money the men had to get the right amount, but I'm not sure... Just curious.
I've been learning over the years, when I find myself in disagreement with nearly all experienced mathematicians in existence, to start with the assumption that I'm completely, shamefully, blasphemously wrong, no matter how it looks to me, and go from there. Because it pisses people off less, and because it's usually true. So, tell me how I'm wrong.
I don't get one-to-one correspondence as a way to measure infinite numbers. I understand(the nonrigorous version) how it works, and I can see how it's a natural extension of normal counting, but it's not how I think, and it's not how I've ever seen infinite numbers. Take the alleged one-to-one correspondence of, for instance, natural numbers and their subset, even numbers. That doesn't make sense to me. Even numbers are sections of an extent. It doesn't make sense to rip them off the number line, jam them together like the vertebrae of a crash victim, and shove them back on, while not doing anything of the sort to the numbers they're being compared to. Here's how I'd compare them, and here's where I need correction. They are each prespecified, patterned, easily identifiable sections of an extent of number line. It is guaranteed that no natural number can exist that is more than one away from an even number, and no even number exists that is not a natural number. They are already, inherently and inextricably, in a particular correspondence with each other. So, take a number x. x can be anything we want, a positive number of some amount. Now, count the number of whole numbers up to (and including, if possible) x, and the number of even numbers up to and including x. Keep doing this as x grows, and let x pass each and every natural number in turn. How many natural numbers will there be as it grows? floor(x). How many even numbers? floor(x/2). What, then, is the ratio of whole numbers to even numbers? 2:1, not 1:1 I'm think the rules of limits back me up on this. This is just a long (and hopefully clear) way of saying what seems so obvious to me: that there are many many whole numbers, and exactly half of them aren't odd.
This last bit is assuming I didn't screw up above. I can understand how the lack of one-to-one correspondence is excellent reason to separate different infinite numbers, but why do people seem to think that the presence of it proves they're exactly the same? Any help is appreciated. Black Carrot 23:34, 15 June 2006 (UTC)
That's a pretty impressive response. I've read them carefully, and I'd like to list the main points, so you can tell me if I've left any out. I'll respond to them as I can.
BTW, please don't toss comments into the middle of my post. These discussions are a lot easier to follow if they stay chronological. I'd like to boil the answers down even further, to the things that seem most important.
Using these responses and the language in them, I'd like to rephrase my original question in a clearer, more concise way: "Is the idea of one-to-one correspondence really the only valid way of showing infinite amounts are different from each other? Doesn't it seem like they could be separated out more than that? How about this way that makes sense to me; it seems just as common-sense as one-to-one correspondence, yet gives an answer that seems more right." As best I can tell from the responses, I was both right and wrong, which I see as a net success. All further comments and corrections are welcome. Black Carrot 19:42, 16 June 2006 (UTC)
That's the kind of talk I like to hear. Thank you, and may the Invisible Pink Unicorn protect you and your family from the ravages of the Purple Oyster (of Doom). Especially, thank you for telling me the name of what I was grasping at (it's amazing how much of math is vocabulary), and for confirming that it's not a completely insane/uneducated/baby-with-blocks-like idea. Black Carrot 02:08, 17 June 2006 (UTC)
This is entirely accurate.
Simplify both sides two different ways.
Divide both sides by (x-x).
Divide both sides by x.
Look what I got. Can anyone explain? Political Mind 01:32, 16 June 2006 (UTC)
Brilliantly simple. So when I am at , it is really ? Ok, thanks! Political Mind 01:37, 16 June 2006 (UTC)
Thank you, will change. Political Mind 01:46, 16 June 2006 (UTC)
In a differential equations textbook I'm working with, there's an exercise where the student is asked to compute the Laplace transform of the function f(t)=t*sin(ωt). Doing it from the definition, by integrating t*sin(ωt)*e^(-st) from 0 to infinity is tedious, but works. The book offers a hint for a simpler method: begin with the fomula L[cos(ωt)]=s/(s2+ω2), and just differentiate both sides with respect to ω. This works out nicely enough, as long as you assume that differentiation w.r.t. ω commutes with the Laplace transform operator, but that seems like a highly unobvious thing. Can someone help me see why it's valid to say that d/dω[L[f(ω,t)]]=L[d/dω[f(ω,t)]]? - GTBacchus( talk) 02:58, 16 June 2006 (UTC)
Can anyone give me a rigurous proof based in the formal definition of limit? Thank you very much ;)
What I would like my GRUB to do is the following:
All this comes from me wanting to use the same partition for the two OS's paging space. Anyone knows if it can be done? Thanks in advance. Cthulhu.mythos 09:46, 16 June 2006 (UTC)
Hi, some time ago I asked this, I have given the link.
I wanted to know, if you had a covariant functor F from the category of R modules to the Ab category, how you could see the left derived functor as a functor, from to Ab
Now there were people proposing I go to derived category but it still doesn't clear things up.
This is my proposal to understand this for myself :
see L_n F as a functor from the category R-modwpr to R-mod
R-modpwr is the category , of which the objects are pairs with M a left R module, and C a positive complex, over M
morphisms between them are morphisms between and , along with a chain morphism \alpha (for which everything commutes) I mean if :
then
So my module does really depend on the chosen complex over the module.
Is this the best approach? Or am I just way off with this. It seems be the only way I can understand it.
Evilbu 17:30, 16 June 2006 (UTC)
Please. I couldn't find one.
What is the smallest simply connected polyomino that cannot be tiled to fill the plane using translation, reflections and rotations? -- SGBailey 23:18, 16 June 2006 (UTC)
Yo,
So it seems that since MD4, MD5, SHA, SHA1 etc are all "broken", with a recommendation not to use in new infrastructure implementations, they must not have been "proven" in the first place. What I mean is that there was a day when MD5, for example, was thought secure, let's say in 1995, and this meant that some smug researcher could say: "You know, if every computer at this university were networked and at my disposal, there still wouldn't exist a set of instructions I could fill their memory with such that if left plugged in for 72 months, the array would be guaranteed to churn out two distinct files with the same MD5 checksum by the end of that time. Maybe within 100+ years, but not in 72 months." (The 100+ years is meant to allude to brute-forcing without reducing the bitspace, whereas the 72 months alludes to the fact that MD5 is in fact "broken" and does not require a full brute forcing).
So, in fact, this researcher would have been wrong, because even without newer technology (using his 1995 university equipment), we can now construct a set of instructions (program) that, were he to run it on all the computers at his university, would produce the collision in 72 months instead of 100+ years. So what I mean is that a mathematical proof must not have existed in the first place that no such program could exist.
So, now, I am asking, is there any hash function today that isn't just wild conjecture, but actually PROVEN not to reduce to fewer than x instructions on, say, an i386 instruction set to break?
As far as I understand it: does any hash have a mathematical proof that no program exists (the turing computer cannot be programmed to) to produce collisions in fewer than 2^x operations, where x is guaranteed to be at least a certain number?
I understand that quantum computing can "break" cryptography, but only in the sense of using a different physics. No program will make the computer in front of me turn into a quantum computer, but surely there is a hash for which there is a proof that no program exists that will turn the computer in front of me into a speedy collision-producer ???? —The preceding unsigned comment was added by 82.131.188.130 ( talk • contribs) .
If you proved that finding collisions for a given hash function could not be done in polynomial time, that would prove P!=NP What about proving that, although the time is polynomial, the factors mean that a theoretically optimal program on i386 architecture with unlimited RAM (as for an arbitrarily large cluster) could not produce an answer on average in fewer than 10^x operations, where the number of zeros (x) puts it out of the reach, at least, of THIS computer over the course of 24 hours???
Okay, I just realized that what you think I want is a proof that finding collisions will take more than polynomial time (for example, exponential time). However, I don't need this. It doesn't matter if a collision can be found in exponential time. It doesn't even matter to me if a collision can be found in CONSTANT time, as long as it guarantees that the constant value translates to more than x operations. I don't care how it scales theoretically, I care about the actual proven minimum. I don't want to hear "Hahaha, just kidding. Tricked you good we did, us mathematicians, because now you can crack [find a collision for] SHAxxx on a rusty laptop from 1987 in 35 minutes." That's essentially what happened to MD5 (read that article, and SHA). Now I want something that that won't happen to. At least, not on a normal computer.
Thanks for everyone's input! I'm putting the short answer in the section below. The only question I still have is whether RandomP's original answer referred to just putting in "precooked answers" into the laboratory computers, and therefore "getting" them instantly. Of course, I referred to getting them algorithmically, rather than just coming back from time with precooked example answers. (Of which of course there are guaranteed to be many, as RandomP seemed to correctly point out). I wonder how to phrase this issue more rigorously, so that "coming back with precooked answers" is ruled out.... I'll ask this in a new question below. 82.131.190.200 18:45, 20 June 2006 (UTC) excde
The short answer is "No, no (non-trivial) bounds have been proved for any hash function."
OK, I've been have trouble watching some videos on Mozilla Firefox... I've tried downloading all the plugins on this page ( https://pfs.mozilla.org/plugins/?action=missingplugins&mimetype=application/x-mplayer2&appID={ec8030f7-c20a-464f-9b0e-13a3a9e97384}&appVersion=2006050817&clientOS=Windows%20NT%205.1&chromeLocale=en-US).
And it still won't work and it won't give me a plugin recommendation.
This is what I get when the video won't work... http://www.esnips.com/doc/2968f507-91c0-4e20-b991-8bb90e9fd09a/Mozilla-Friefox-Problems.jpg
Thanks! ~Cathy T.~
It does this on my mom's pc too... ~Cathy T.~
Yeah, that's what I've been doing... using internet explorer. Going to check out that extension. Thanks! ~Cathy T.~
Thanks... I just downloaded the extension and it works! Thank you so much! :) ~Cathy T.~
Yeah, it's updated. ~Cathy T.~
Hi,
I have been studying homological algebra and I have seen several important theorems, but I still haven't found any theorem (in my syllabus or on the web) that is called 'The fundamental theorem of homological algebra'.
Is there one? (because if there is I would feel a little silly studying all this and still not knowing what it is..:))
If so , my guess would be that it is the theorem about connecting morphisms, that allows you to create a long exact sequence of homolog y modules from a short exact sequence of chain morphisms?
Or is this the one, but in a much more general abelian category?
Thanks,
Evilbu 08:42, 17 June 2006 (UTC)
Hmm, but once I read an article, I think here on Wikipedia, about math in popular culture, and I think it said something about a movie in which a professor 'demonstrates the fundamental theorem of homological algebra for an obnoxious student'.
It is a shame I can't find it back.
But you think there isn't one? If I had to force you to pick one which would it be?
Thanks,
Evilbu 11:12, 17 June 2006 (UTC)
Thanks. And it was also crucial in Mayer Vietoris in topology hmmm. But I mean wouldn't the most general case, involve abelian categories. But I was wondering, how would you go about categorically defining quotients (for homology modules?)
Evilbu 16:06, 17 June 2006 (UTC)
The "movie in which a professor 'demonstrates the fundamental theorem of homological algebra for an obnoxious student'" is probably a film called It's My Turn (look it up on imdb, I haven't seen it though I'd love to find a copy...) in which someone proves the Snake Lemma on a blackboard. This isn't really a good candidate for the "fundamental theorem of hom. alg." though. It's My Turn gets referenced in Weibel's book An Intro to Hom. Alg. -- 86.15.136.29 22:58, 24 June 2006 (UTC)
Hello. May somebody tell me how to find the limit of the following sequence?
lim 1/n * ( (n+1)(n+2)...(n+n) )^1/n
n->infinity
Thank you very much for your patience.
Is there a compact integration of the formula sin(x)/x? Black Carrot 21:03, 17 June 2006 (UTC)
Hi. If possible could someone please confirm the following relationship between function and the derivative I've found. I'm getting some answers right and some wrong with this equation, so I'm not sure if the textbook is wrong or I have a equation that works some times and not others.
Thanks, -- DanielBC 22:46, 17 June 2006 (UTC)
If anyone here has a copy of Stalking the Riemann Hypothesis: the quest to find the hidden law of prime numbers, I need some help. He explains things very clearly for about the first third of the book, then starts leaving out more and more details. On pages 85-90,
The Plasma TV manufacturer Panasonic produces widescreen plasma TV model X. If they price it at $20000 then they can sell 50 units per week. If they half the price to $10000 then they can sell 500 units per week. If they half the price again to $5000 , they can sell 5000 units per week. And finally at a price of $2500 they can sell 50000 units per week.
The actual selling price for the widescreen plasma TV model X is $2800 dollars. What is the actual cost of the TV.
I have calculated that the volume sold is
Vol = 5 * 10 ** ( 1 + (log(20000/price)/log(2)) )
or
The total profit is
Which we can plot as a X,Y graph
Setting the Cost to $1000 , produces a graph with the maximum y at x= 1426
Refer to this graph.
My question is this. Apart from changing the value of Cost and reploting the graph. How else can I find the value of Cost which correspond to a graph with the maximum value of y(Total Profit) at the point of x=2800 (Price = $2800).
Ohanian 02:41, 18 June 2006 (UTC)
Your derivative is wrong. It produces the cost of 2189 instead of 1960.
211.28.122.175
09:56, 18 June 2006 (UTC)
So I need to find the derivative of this
211.28.122.175 10:02, 18 June 2006 (UTC)
Not essentially different, but a bit less strainful in some respects.
Start by rewriting the expression for the profit in the form:
in which C is the cost. For the purpose of finding a maximum, the value of a is irrelevant, but λ = (log 10)/(log 2) ≅ 3.3219. Taking the derivative with respect to x yields:
which is zero for:
or, plugging in the numeric value for λ,
The value 0.6990 is 1 – 0.3010, where 0.3010 is the base-ten log of 2. -- Lambiam Talk 13:12, 18 June 2006 (UTC)
I've seen a symbol that looks like an integral symbol with an "o" in the middle of it. What is that symbol? -- Shanedidona 03:27, 18 June 2006 (UTC)
Actually i want to make a story and wanted to know how to make a simple virus.
Hi, i am having problems understanding the differences between the secant method and the method of false position. I have an exam tomorrow so any help would be appreciated. The formulas look pretty much the same and they seem to do the same thing so what's going on?
chemaddict 13:20, 18 June 2006 (UTC)
Hi
If I'm too dense to understand the Ring theory article, even by using the internal links to explain the explanatory terminology (words like "and" were OK... most of the others were beyond me) is there any way I'll ever understand what the heck Ring Theory is?
You may have gathered that I'm no mathematician... but I have a friend who is. He specialises in Ring Theory. And he is utterly incapable of explaining it.
Based on those tips, let me try to give an idiots' definition: Simply put, a ring is a place where the "normal" rules of addition and multiplication work. Is that it? -- Dweller 15:25, 19 June 2006 (UTC)
"Yes" I understood. Everything below it was wasted on me. I particularly enjoyed learning that "for every number a there is also a number -a." The whole thing seems inherently contradictory. What would be a workable idiots' definition? -- Dweller 16:33, 19 June 2006 (UTC)
If you are "too dense" to understand a given article, see if there is a simple english version of it. Russian F 23:39, 19 June 2006 (UTC)
Here the problem -
There are two computers,their respective LANs they connect to the internet via their respective proxy servers
Computer A -- Proxy server1 <Internet> Proxy Server2 ---- Computer B
Now is it possible for computer A to computer B and transfer data ?
It is possible for them to transfer data using a common server on the internet,which is whati think yahoo messenger and google talk does to transfer text from one computer to another. They both can connect to a single server and transfer data but if they have to transfer large files it will eat up the bandwidth on the server.
I managed to figure a technique called 'NAT Traversal', but I think it is limited to cases where computers connect to internet using NAT and not proxy servers.
musing: I am behind a proxy server and BitTorrent clients like the official client, Bit Tornado etc dont let me download even a single byte,at the most they have an option stating they can 'proxy the communication to the tracker using the proxy' which I think is extremely trivial. But with clients like Bitcomet, they can proxy even my data, so I can seamlessly download anything,with great speeds. (I downloaded FC5 at speeds around 70-100 KBps which is great on my connection)
This indicated it is possible to achieve this, but how ?? —The preceding unsigned comment was added by 203.145.128.6 ( talk • contribs) .
I have a blog and want it to display a fake blog-page for a certain IP address. That way a certain computer won't be able to see what's really on my blog. I would like to know how I can do this.
Goedel's completeness theorem, if I am not mistaken, proves that any logicall consistent statement can be proven in 1st order logic. Goedel's incompleteness theorem, if I am not mistaken, proves that there exist mathematical truths unprovable by any set of axioms in 1st order logic. But surely a mathematical truth is also logically consistent and can be proven using 1st order logic? How are these 2 theorems reconciled?
I have a polynomial of the form:
and have a few questions.
Thanks for any help.
x42bn6 Talk 01:43, 20 June 2006 (UTC)
I badly want to understand monstrous moonshine. I'm very good at math and I already know the basics of group theory and complex analysis, but it's still tantalizing gibberish to me. Here's the bulletin for the math department of the university I attend: undergraduate and graduate. What courses should I take in order to understand monstrous moonshine? — Keenan Pepper 04:53, 20 June 2006 (UTC)
changes in agriculture in the world till today
I would like to state requirements for a proof in terms such as "This architecture (i386) cannot produce collisions in fewer than approximately 100 billion operations" on average (as a simple bounds), so, for example, 100 seconds for a 1 GHz cpu, or less time if you use higher speed or multiple cores/nodes. I'd like to phrase this like this: "Here is an idealized computer, it's a Pentium 4 with 1 core running at 2^32 hertz and accessing 2^32 bytes RAM" (I guess to idealize further we could assume the full ram is full-speed cache, assuming zero latency and more bandwidth than the CPU can consume in a cycle). "Does there exist any digest algorithm (hash) that is proven not to be 'breakable' in fewer than 1,000,000 such processor-hours for a certain length? ( This question was answered above, and the answer seems to be "no"). However, the issue is that in fact the answer as I asked the question is literally "yes" since you can get two files with the same checksum/md5 sum etc in 0.1 seconds, if you just bring back the files from the "possible" (since the pigeonhole principle guarantees they exist.) Of course, for short files (like 4-byte files) you can just brute-force it on the spot. So I want to rule this out (brute-forcing based on the small file length) and also rule out bringing in homecooked files. How do I rigorously phrase my algorithmic requirements?
My friend found that in two dimensions, there can only be two lines that form a perpendicular at one point. In three dimensions, there can be a maximum of three lines intersecting and forming perpendiculars with each other. So he said that by continuing the pattern: In four dimensions, there can be four perpendiculars, with time as the fourth dimension. I understand what he's saying but I don't agree. Is this true or not? -- Yanwen 20:15, 20 June 2006 (UTC)
(stolen from Martin Gardner) A square has two diagonals, which intersect at right angles. This corresponds to the fact that a square is two-dimensional. A cube has four spatial diagonals (each of the eight corners is joined to its opposite corner) which intersect at right angles. Hence a cube is four-dimensional :). (Exercise: find the fallacy in this argument.) — Blotwell 02:53, 21 June 2006 (UTC)
Just to make this more fun, lets change the question a bit:
In all cases, the given flats are "in general position".
Answer: 2,5,14,42. The last is of course the answer to the universal question. The questions and answers exemplify Schubert calculus, by the way.--- CH 22:31, 21 June 2006 (UTC)
is there a quick way to make a formula that tracks and record visitors to a website and compares them to other websites?-- Bee( y) T i 01:32, 21 June 2006 (UTC)
I am sure there is a quick way to make such a function. previous_hits + 1 = current_hits It is called a hit counter. However, if you want something specific, the particular programming language you plan to use would be required to formulate the function. -- Freebytes
We know that to find the co-efficient of the principal part in the expansion of a complex function f(z),we can use the residue theorem.BUT z=x+iy, so y=0 gives f(x).So can we use this residue theorem to find the co-efficients of any function in case we need to partialty fraction them?
Just in case, Residue of root a of order m R(a,m)=(1/(m-1)!)*lt[z tends to a]{(d/dz)^m-1 (z-a)f(z)}
Hi, Can anyone tell me which is the most complicated or longest equation ? I know that complicated equations need not to be longest.But just curious as which could be the longest equation existing.
What I am asking is any textbook mathematical or physical equation. A very simple example would be E = m×c2 .
The Lagrangian (and therefore also the equations of motion) for the standard model are so long in most notations that they can't fit on a single page. - lethe talk + 11:31, 21 June 2006 (UTC)
In celestial mechanics, the literal expansion of the disturbing function in terms of orbital elements is an ugly beast, even to low order in the eccentricities and inclinations. In other news, how do we not have an article on that? Melchoir 19:31, 21 June 2006 (UTC)
Could you please help me with the following table for macroeconomics, I understand which each column represents but am having trouble with the math. If someone could complete the first row I should be able to figure out from there. I know I, G, and X are constant. Does AE have to equal Y? Thanks
Y C S I G X M AE 100 200 300 400 500 600
Given the following:
C = 50 + 0.75Y M = 40 + 0.15Y I = 30 G = 20 X = 100
Y C S I G X M AE 100 125 30 20 100 55
You will get a bit further by noting the basic macroeconomic identity:
Y = C + I + G + X - M
AE stands for Aggregate Expenditure and is defined as
AE = C + I + G
Savings S is defined as what is left over after subtracting consumption C from disposable income (Income less Taxes):
S = Y - T - C
You do not have an expression for Taxes, so it does not seem you will not be able to fill out the S column. In a problem like this Taxes might typically be described by an equation such as T = t*Y where t is a tax rate.
Vickrey 18:42, 24 June 2006 (UTC)
Did anyone have any luck on my macroeconomics question?
Has any name been given to the numbers x^2 + x (x integer)? I am interested in them because (x + .5)^2 = x^2 + x + .25, and these "half-integer squares" can also be used in Fermat's factorization method a^2 - b^2 = N to produce factors (a-b) and (a+b) of even numbers; as you can see (a-b) and (a+b) are still integers, with both a and b half-integers. -- Walt 15:42, 21 June 2006 (UTC)
Thanks guys. Any opinions on the appropriateness of cross-referencing the article to/from perfect square? Or is the relationship only obvious from the problem I'm working on? -- Walt 12:42, 22 June 2006 (UTC)
how do i solve this? 88.153.89.18 09:52, 22 June 2006 (UTC)
Yet Another Linux Question... :)
I will soon take the plunge into Linux, and am planning to set up a dual boot Ubuntu / Windows XP system for the time being, so I can experiment with both OSs, and hopefully use the advantages of each as best I can. I have some Linux experience (from working with it at the lab), but not a huge amount.
My question: what do you recommend as filesystems? I have been trawling through the Wikipedia articles on the various filesystems to see what filesystem is compatible with which OS. I am trying to achieve a compromise between performance and compatibility, and will obviously need at least two different ones...
FAT is readable and writeable by both Windows and Linux, however, I detest it with a passion (I have long since stopped counting the number of defrags I've had to do on it), plus, the filesize and volume size limitations will probably come back to bite me. I would prefer to avoid it if I can.
How good is read / write support for NTFS in Linux? (the external links at the bottom of the article point to several projects, but I must admit my techie knowledge is insufficient to judge them).
Conversely, it seems that ext2/ ext3 read/write support seems to exist under Windows (again, information gleaned from the articles) - does anyone have any experience with this?
And, to close, a somewhat more basic question - in your experience, how much do you find yourself needing read/write access between your different OS's partitions on a multiboot system? Do you have any advice for me in this regard? Thanks muchly in advance! — Quantum Eleven 12:23, 22 June 2006 (UTC)
Hello, How do we easily find a biclique in a bigraph, after applying bigraph crossing minimization heuristics (like by barycenter) to reorder the two vertex sets of the bigraph. This paper "SPHier: Scalable Parallel Biclustering Using Hierarchical Bigraph Crossing Minimization" suggests that we use Breadth First Search after this reordering procedure, but I'm not sure how exactly this is achieved. In their example Figure 1(C), supposing we started on node Y, BFS (ignoring loops) will wield nodes A, B, W, X, C, D, Z. I'm not entirely sure how we extract the bicliques {A,B} + {Y,W} and {B,C} + {W,X}. I'm sure the answer must be pretty obvious, but I'm missing something here.
Many Thanks ! -- 213.22.236.27 20:55, 22 June 2006 (UTC)
Hi folks; I am writing a dissertation on the nature of Time. Why ? Because we know nothing about it.
I have written about the human perceptions of Time, and have compiled 7 axioms. I now need the assistance of a mathematician to create and formulate the maths.
So this is more of an open request for assistance than a question. I live in BC, Canada.
Kind regards, Bruce >>>>>
Yes I have read all of those references (and their sources), many times. Interestingly, Albert said very little about Time itself, other than to clearly define the (human) ways of measuring simultaneity and the consequences arising therefrom, across distances and with relative speeds of observers. But, Time is not measured by humans. Our clocks simply emulate time with great precision. Our science knows nothing about it. We need to sit back and think again. Cheers, Bruce >>>>>
Yes, I am concerned about the physics of Time; the philosophy will take care of itself as we develop the mathematics. OK, I don't know whether it will be as simple as F=ma or it will be vastly more complex. Currently, I believe that there is some linkage with String Theory. Time-lines connect everything that we can perceive. Cheers, Bruce --email removed-- >>>>>
>>>>> I am now a "logged in " user with moniquer "Time'sup". I am willing to post the draft dissertation as suggested by Igny. Perhaps you folks can point me in the right direction. Cheers, Bruce >>>>>
Kind regards, Bruce bnb at ahausa.com Time'sup 01:34, 26 June 2006 (UTC)
Cheers, Bruce Time'sup 18:07, 26 June 2006 (UTC)
I'm looking for a way to divide one multiple-precision integer by another. One of the things I was looking at was using a number-theoretic transform, but I can't figure out how to get the remainder separate from the quotient. Plus, it blows up if one of the coefficients in the number-theoretic transform of the quotient has a 0 in it. Can someone help? -- Zemyla t 17:11, 23 June 2006 (UTC)
I've done my basic google searching, but my only finds were way over my head. I currently have a SanDisk Cruzer Mini with 1.0 GB, and I'm interested in making it bootable.
I understand how to switch the order in BIOS, but I think there are some needed components to go on my stick, something about bootsectors?
I would be interested in doing this on a computer with XP, if that matters. -- 134.134.136.4 22:52, 23 June 2006 (UTC)
Just a few things: I don't have a floppy drive, didn't think I'd ever have use for floppies again. Also, I'm afraid to format something like a C drive without some sort of confirmation that it is the correct C drive. I'm not going and formatting my only system drive here, right? It's a lot easier and safer for me to format the drive from the Windows GUI with a simple right click. =P. Any Suggestions? -- 134.134.136.4 20:41, 27 June 2006 (UTC)
There is a math code at http://inthemath.com and I have 2 questions 1.)Is it a math code? 2.)Did I make it up? —Preceding unsigned comment added by Lightprize ( talk • contribs) 22:23, June 23, 2006
That's allot. First, whether I did it or not is a waste. If I didn't the law will handle it.
I asked if it fit the description of a code, not whether or not "YOU" thought it was valid-you ain't seen the rest. But are you saying that if it were more complex it would be okay? I think that some say it can't be anything "because" it is too simple.
And I guess you are saying that I did find it, and that I did't make it up? Whether it is valid in your eyes or not.
So did find a code, didn't I?
Predictable? 12 and 3 were predicted. At least that is what I was looking for. And I would not have been able to find them if they were not there.
I have the advantage of having seen more of it than you have. From that, I say it has meaning, and I have provided more than enough. I didn't say it would repair the ozone layer, or bring home those MIAs from Vietnam. So don't expect everything. But can you imagine "if" it were a message, being ignored because the receiver didn't like how it was written?
"If." You see I am not married to the thing. But I am giving it the benefit of the doubt. Nothing I have heard has shown me why I shouldn't. I will keep looking till then, while I try and deliver what it does say.
Those 3 words that you are talking about are 1,5 and 6 and they add up to 12, that makes them part of the original code.
But do you see where you have gone? I had to look up numerology after it kept popping up in your writings.
The code I am talking about says nothing about "magic" numbers" or predicting the future, or getting insight into anyones personality.
You are trying to make it harder then it is, I said I found a math code, I did. The patterns are there, "in math." The number was 12 "what if I reversed it" you say? Why would I want to do that? I don't know anything about the meanings of numbers, other than what they add up to.
Look back at the way you sound, and the way I sound, which one of us is talking about numberology? You are trying to feed that to me, but you have seen the numbers and they are "invincible in their simplicity," why make them hard? Talk about what is there, not what you imagine should be there.
That maybe the simpliest explanation, but it is not the most interesting. What if I thought it wasn't what it seems, and it was? I have to take it at face value, and then be proved wrong. The references I "added" were metaphors, and they sound mean because people were being mean to me. I asked a question about what I found and I got something else. I believe in a designer with evolution as the design-no more.
I looked at Ramsey Theory, and a couple of other theorms, and it occurred to me that science is addicted to complex math. And while I have no doubt about the success of scientific thinking, few outside science can understand it. I know I don't. Science is looking for a formula in math to "unite the forces" so they are looking for a message/code in math, and "know" it is there. How did it get there? And if there was a message/code meant for the "masses",(however it got there)would it be left to science to interpret? Or would it be easy enough for all to understand it? Like the simple, consistent patterns at my site? —The preceding unsigned comment was added by Lightprize ( talk • contribs) .
The question was: since science "knows" that the unity formula is there in math (and I believe them)how did it get there?
Oh wait, I'm sorry. The mathematics behind the four of them would match up into some type of an equation, whatever it was. I was not trying to be funny.
I understand what you are saying, but it seems here that not only is science addicted to complex math, but it also has to communicate in the most complex language it can. A simpler way to say what you did would be that because the forces are united in nature, their math must come together in a math equation of some kind, once the method is found. I was looking for a simple code in math, since everything else was done. I found some patterns, and then some more. I thought they could not be anything, so I checked out the names in other languages, and nothing. So the code was unique. People have looked at where the numbers came from and dismissed them saying they can't mean anything. Where would science be if researchers listened to what people "thought" about what they were doing, without "proving" what they said?
Are the names of the numbers in English arbitrary or fact?
So, the names in English are a fact than.
I don't see where I had allot of trouble, but it took allot of time for those there to say I found the patterns I did. And I thought it was a simple question. Whether or not anyone "thought" the numbers meant anything. Only I (right now) see where those numbers go. And time will tell.
Accuracy, should also be sought in conversation. At which time did I apply the arrangements of letters to quantum physics? Stick to what the numbers say instead of what you "imagine" them to say.
Would you say that there is a certain "brevity and elegance" to the code at inthemath.com? Brevity and elegance is what helped me to see them for what they are.
How long did it take you to get thru the site? Quick, right? That is brevity. All those symbols and numbers did what they did without fuss, and without anything being left out, or left over, thats' elegance. The code will soon show a connection to the theory for everything, but not by counting the letters. Time will tell, and not allot of time either. Accuracy, again. I asked what science was looking for in a message, and patterns and symbols, in math, is what they are looking for. [Lightprize.]
I know this is not the right place for this but, you know how children take on the characteristics of their parents? Well where did the characteristics of life come from? Electromagnetic radiation is 2 energies blended into 1. The characteristics of its electrical part are negative and positive, and those of its magnetic part are attraction and repulsion. That's No, Yes, I like you(love) & I don't like you(hate). That is the mental/emotional nature of life, and math to boot. Because negative is subtraction positive is addition, attraction is multipulcation and repulsion is division. Now this does not have to be right, but it is the best description of the soul of life that I have ever heard. And light is 1 force, made up of 2 parts. Sometimes some interesting things can come from something seemingly of no value. [Lightprize]
Everyone, from that I have seen from the responses, is saying that the issue with your 'discovery' is that it only applies to English, and that numerology consists of people that have found more fantastic 'discoveries' than you. English was not created. Here is an example of a constructed language: http://sipen.com/projects/language/ Notice the differences from a logical viewpoint? Words created in an ad hoc manner are done so in languages that are made by numerous people in most circumstances. If I were to change the name of the word "two" to "cianide" in your language, would your code still work? All it would take to do that is for someone to repeatedly use the word until others began using it. (An example of this is using the word "cool" to mean awe-inspiring or "bootylicious" to mean voluptuous.) -- Freebytes
I recently took a practice SAT test from The Princeton Review and I didn't do very good on the math section. The following are the ones I didn't know how to do.
I would really appreciate any help. Thanks. schyler 01:44, 25 June 2006 (UTC)
I am actually no about to attend college. I am just now going to be a sophomore. The course is specifically designed to have you see what to look for when you are learning the stuff in class, so some of it, I haven't even learned how to do yet. Thank you for yall's help though. schyler 14:12, 25 June 2006 (UTC)
(I do hope this question will not be too lengthy..) I am a 3D animator, so although I am fairly profecient wiht it, math is not my strongsuit. But because I don't feel like spending thousands of dollars buying one, I have decided to code a highly simplified fluid dynamics solver for special effects in my animations.
Note that unlike CFD/engineering applications, my purpose is NOT to achieve complete accuracy, but to create a convincing image.
In my program, the Navier-Stokes Equations are solved on a 3D grid. The velocity and density of the fluid are sampled at the center of each grid cell. I do not fully understand the Wikipedia page explanation of the NSEs, however, I do have a vague understanding of the form Jos Stam presents them in a paper he wrote:
This involves two 3D grids: a vector field that stores the velocity of the fluid, and a scalar field that stores the density of the fluid.
in the first equation: u is a vector representing the velocity of the fluid at a given point, t is a timestep by which the simulation advances each frame, ν is viscosity, and f accounts for the addition of forces by the user.
in the second equation: ρ represents the density of the fluid at a given point, t us a timestep by which the simulation advances each frame, κ is the rate of diffusion, and S accounds for the addition of density by the user.
What I am currently concerned with is the term,
which simply states that the density diffuses over time. To implement this in the 3D grid structure I am using, it seems simple: we exchange the density with the six immediate neighbors of the cell we are trying to solve for. However, if the density in that cell must diffuse beyond its immediate neighbors, this is not accounted for, and the simulation "blows up." The only soltion is a shorter ∂t, a smaller κ, or a finer grid with smaller cells. In any case, the effect of diffusion is either lost, or the simulation takes much longer.
Stam wrote a solution for this which is quite elegant--he uses Gauss-Seidel Relaxtion to solve for the new value. It is stable and will not blow up. It is also patented, so I cannot use it.
Given that I am striving for visual appearance and not accuracy, it occurred to me that the effects of diffusion look strikingly similar to the Gaussian Blur filter in many graphics/image manipulation programs. It seems logical that a fast 3D gaussian blur would do the trick for me and work at any time step.
So I look it up on Wikipedia. Apparently, to get a convulsion kernel with Gaussian distribution in 2 dimensions, you use:
Let me be frank--I am only attempting this project because of the simplicity Stam's paper provided. I do not know a whole lot about higher math, so bear with me if this seems like it should be obvious.
My question is: What would this Gaussian distribution function look like in 3D? My guess would be:
is this anything close to correct??
Jos Stam's website is http://www.dgp.toronto.edu/~stam/reality/index.html. The article I am basing my program on is the publications link, it is entitled, "Real-Time Fluid Dynamics for Games."
Although I suppose I could use Stam's code for personal use, I may distribute the code to some friends, and I do not want to risk anything, since I have no attorney... So I am fairly dead set on staying away from the patented section of the code.
Any help would be much appreciated --
Loki7488
09:15, 25 June 2006 (UTC)
I have the slideshow in PDF form, it expands on the paper I am currently reading from and I'm sure I will refer to in as I progress. I have also read many papers written by Ron Fedkiw, Nick Foster, and Dimitri Metexas. I am fully aware of the challenges fluid dynamics presents, and that professional outfits have huge physics teams who get paid top dollar to do this stuff to the extreme... on the flipside, I am also aware of numerous individuals or groups of individuals who have developed very simple fluid solvers. Thanks everyone for the helpful replies! -- Loki7488 14:39, 25 June 2006 (UTC)
The Half-life computation article has undergone substantial revision which has hopefully addressed everyone's concerns. If you have any further comments after looking at the article again, please list the items you do not like, make whatever comment you have and please be specific and allow time for further revision. If there is any reason I can not comply with your wishes then I will let you know the reason why. ... IMHO ( Talk) 12:20, 25 June 2006 (UTC)
Hello,
my sister, who studies informatics and has exams just like me, asked me if I recognized this symbol :
an equality sign with a dot above it
\doteq in latex, but it doesn't seem to get rendered here.
I had seen and stuff like that, but never that.
It appeared as a sign between two membership functions in fuzzy logic (the syllabus is about artificial intelligence).
Can you help me?
Evilbu 16:45, 25 June 2006 (UTC)
How many feet are in heaven? -- 63.170.208.190 17:55, 25 June 2006 (UTC)
I've been grappling with this concept for a while. Now, while I realizes calculus states that .999... theoretically equals one since it's infinitely close, it also states that it will never equal one, since there will always be an infinitely small gap between the numbers. However, consider this equation:
Since it's been established that x=0.999:
Therefore,
I know that practically, this is impossible, since adding no amount of decimals will ever cause 0.999... to actually reach one. How, then, does this equation work? If this problem's already been posted, please accept my apologies in advance. -- Thetoastman 07:11, 26 June 2006 (UTC)
your problem is that you don't picture infinitely many 9's, you just picture them repeating. They don't "repeat" one after the other (this repeating is the process you're imaginging), mechanically or something, taking a bit of time to add the next one: just imagine them all there all at once. Imagine a make a computer game where you live in a town, and in one direction train tracks go off forever, since I don't program them. You can't follow them, because the game doesn't let you leave the town. Now, the tracks are "generally anchored perpendicular to beams (termed sleepers (Commonwealth except Canada) or railroad ties (U.S. and Canada) of timber, concrete, or steel to maintain a consistent distance apart." If you cast a spell "railroad beams to snakes" that turns EVERY railroad beam into a snake, it doesn't matter if you first add a beam where you can still walk to. If instead of "railroad beams to snakes" you just cast "infinite snakes 2 feet apart" and the beams are 2 feet apart, then if you point it parallel to the train tracks, each beam will get a snake. It doesn't matter if you remove the first beam yourself and take a step forward before casting the spell.
Likewise, there are as many positive numbers as negative and positive numbers together, since you can just count them like this: tracks: 1 -1 2 -2 3 -3 4 -4 5 -5 etc. snakes: 1 2 3 4 5 6 7 8 9 10 etc. It doesn't matter.
Likewise, if you start counting at 8 and I start counting at 1, we can count together forever. You won't "run out" 7 numbers before I do.
(This anonymous comment added by 82.131.190.16)
can you please help me to make a bootable disk.-- Saksham Sharma 11:55, 26 June 2006 (UTC)
On windows.-- Saksham Sharma 03:55, 27 June 2006 (UTC)
On windows XP service pack 1
Rotating objects – as wheels on automobiles – appear stopped on TV screens.
What is exact way to calculate probable car speed?
Is it proper to count the “spokes” , assume a wheel diameter, assume a TV frame rate of 60 Hertz, or what?
Please show exact step by step procedure to arrive at an estimate.
I hope this isn’t a stupid question but where will I find this answer if someone responds? -- Itserp 14:52, 26 June 2006 (UTC)
How many mathematicians does it take to change a lightbulb? -- Dweller 20:32, 26 June 2006 (UTC)
That's the spirit! If time is sufficiently curved, perhaps you're still in time to retrospectively beat the scientists. -- Dweller 16:23, 27 June 2006 (UTC)
What is the title of the famous math novel involving shapes of varying dimensions (3d, 2d, 1d) visiting one another and being unable to comprehend anyone of a higher dimension than their own. I believe a rectangle visits a 1-dimensional world to tell them about two dimensions or something. I'm sorry I don't recall much more, but I saw an article on it on Wikipedia several months ago and was thinking about reading it now that I have more time on my hands. - Dave 04:17, 27 June 2006 (UTC)
I am looking to get information on comparing power pc's with Intel processors under the following headings: architecture, cache, speed, power consumption, heat dissipation, future prospects for Intel. If you could give me a few useful links I would appreciate it
show that tan 15+cot 15=4
Is there (Mac) software to allow the remote use of a computer over a fast local network at fast enough speeds to make no visual difference? For example, I want to use a desktop Mac via a (Mac) laptop, but at full refresh, large resolution and 32 bit colour with very little lag. This would be for general real-time use rather than admin purposes. Finally, it would not be X, but a streamed display.
In fact, is this even possible?
I am looking for an online LISP environment to do things in, I would like to be able to save programs as well, can anybody give me a link?
wat is the principle of GESTALT VALUE ? -- 59.161.8.150 15:09, 28 June 2006 (UTC)Roman Nagpur.
this may have to do with something that is 'holistic' and has to be viewed as a hole instead it will not be comprehended. it can also refer to completing an experience...but I don't see how can it be applied to math because it's a psychological concept.-- Cosmic girl 19:51, 10 July 2006 (UTC)
how do we calculate the product of ((r^2)-1)/(r^2), where r = prime numbers starting from 2.
Hello,
I am in need of an automated process (registry file, script, etc.) that I can run on several Windows XP computers that will perform two actions:
1) Add the volume control speaker icon to the taskbar system tray.
and
2) Mute the master volume.
Repeated searches of Wikipedia have yielded no assistance in solving this for me. I've also done some Google searching but have yet to find a solution. Your help would be greatly appreciated!
Thank you.
Hi Guys and Gals! Wikipedia defines percentage as:
"...a way of expressing a proportion, a ratio or a fraction as a whole number,.
what if a percentage is expressed in decimal form? (e.g. 2.45%)
Is there an exact term to call it? Thanks for your help.
In August I'm having a large outdoor gathering, a party of sorts, at my house. I'd like to have iTunes playing music for the roughly 100 guests who will be just outside the house (i.e. not very spread out). What I'm looking for is ways to have good quality sound played outside with equipment that I can use for some other purpose once the gathering is over. Like using it for a stereo set up that I don't yet have or using it for an improvement over the stock speakers on my television or playing music from the computer throughout the house etc.
What I'm working with is a dual 1 Gig G4 tower. If there's a need for wireless, I'm using a Sonnet internal card for wireless internet with a Linksys wireless router. I also have an iPod (and iTrip) which will be able to hold the desired playlist if need be.
What's the best (while not going into thousands of dollars into debt) way to do this? Dismas| (talk) 07:52, 29 June 2006 (UTC)
Hi, I have looked at the optimization, lagrange multiplier and quadratic programming. I have some confusions here. Suppose we are consider optimization in Euclidean space. Since the use of lagrange multiplier can be reduce our problem from constraint to unconstraint ones, and also can be used for all non-linear problem, why do we have to invent some other techniques such as linear/quadratic programming, or some heuristic such as simulated annealing ? -- 131.111.164.110 11:05, 30 June 2006 (UTC)
Thank you for all answers; Then can I just conclude that we have many methods to attack many specific problems, mainly for the reason of efficiency? 131.111.164.226 13:50, 3 July 2006 (UTC)
I was thinking of a pattern in which you start with two numbers, say 1 & 10, and add one to the first number and subtract one from the second number, and take the product of every pair. For example:
1*10=10
2*9=18
3*8=24
4*7=28
and so on.
I decided to graph this, except using a larger range (-10*21 to 21*-10) and a smaller interval (one tenth). The result is the graph you see on the right.
I am guessing this is a parabola, simply by what it looks like, but is there any way to tell if it is one?
Thanks for any help.
-- Tuvwxyz 21:53, 30 June 2006 (UTC)
Hello,
You are given that the complex number alpha = 1 + j satisfies the equation z^3 + 3z^2 + pz + q = 0, where pand qare real constants. (i) Find and in the form a + bj. Hence show that and p = -8 and q = 10 [6] (ii) Find the other two roots of the equation. [3] (iii) Represent the three roots on an Argand diagram. [2]
Thanks guys as always. DR Jp.
How much time is needed to travel around the world for the following modes of transportaion -- the space shuttle, a jet airliner, a cruise ship
I have a group of 12 observations. I'd like to predict what my observations will be in the future. I also need the distribution to apply Bayes Theorem.
Right now, I'm using the normal distribution but I don't know if that's the right choice. I've calculated the skewness and kurtosis of the data, but I don't have any idea what they're supposed to be! I mean, I know if my observations were truly normally distributed, the skewness would be zero, but I don't know if my skewness of 1.65 is "close enough" or what. Are there rules of thumb for this? moink 05:50, 1 June 2006 (UTC)
Ok, here is this little idea I had today. It has the potential of solving all problems of theoretical physics in one stroke of genius. Basically, the idea is that the interactions in the world are subject to very simple rules, namely Newtonian mechanics. But hey, I hear you say, wasn't there a guy called Einstein who has proven Newton wrong? Well, he did, but it would be Newton who will be having the last laugh.
The world of Newtonian mechanics is very simple: a Euclidean space and a few differential equations, solutions of which are nicely differentiable curves. There is one problem with this world: it is continuous, which makes its "implementation" extremely hard. There are no continuous things in our world: the space is discrete, the time is discrete, and this brings us to the next point: the world is a finite state machine. The world is, basically, a computer. The bit-twiddling aspect of our world is studied by quantum mechanics.
N-body problem is a classical problem of mechanics. There are a few particles floating around in space under the Newtonian law of gravity. It translates into a system of differential equations, which in general is not solvable by mathematical means. We'll try to simulate this problem on a computer. When n=2 theory states that these two bodies would have elliptic orbits (well, not exactly, the orbits may also be hyperbolic or parabolic, but we assume that they are ellptic). What happens when we simulate this on computer? At first everything seems okay, the smaller planet rotates around the bigger one. Let's modify the program so the path of the smaller planet is visible. Then, after a few rotations we'll see a strange effect: the elliptical orbit is slowly turning! More interesting is that the same thing happens in real life: a result predicted by General Relativity theory. But isn't it strange, that Newton's law of gravity when emulated on a computer produces the same effect?
There are several numerical methods for solving differential equations. They all have the same flaw: when you run the method for a long time, round-off errors and discretization errors build up and the result strays off from the right solution. The same thing happened in our simulation - during the rotation the error builds up as we do little discrete time steps, and it rotates the orbit. The same thing, I suspect, happens in our real world, which faithfully tries to solve Newton's differential equation by discrete means.
Comments are welcome. Grue 12:36, 1 June 2006 (UTC)
Any crypto fans here? I need to generate object IDs from other object IDs to mask the true object with one that is a plausible replacement.
Say I have a unique object ID, is there an encryption algorithm I can use against it to produce a different (cyphertext) object ID that is one way (can't easily get the original plaintext Object ID from the cyphertext Object ID, either not at all, or at least short of a computationally expensive attack), and unique, meaning that no 2 original plaintext object IDs produce the same cyphertext object ID and that I never get different cyphertext object IDs from the same plaintext object ID. The text lengths need not be the same I guess, although obviously the cyphertext one can't be shorter. I have looked at Message_digest and it speaks of cypher/hash functions that are unlikely to have different plaintexts go to the same cyphertext. I need guaranteed... the cyphertext length need not be a hash, it can be as long or longer as the original (exactly the same size would be convenient, though). thanks! + + Lar: t/ c 18:34, 1 June 2006 (UTC)
A method that gives good scramble of an N-bit string is to XOR it with a randomly chosen bit string, apply a randomly chosen permutation to the bits of the string, multiply modulo 2N with another random but odd bit string, and XOR+permute again (using different choices). Since each step is invertible, you are guaranteed to have no collisions. For additional security the procedure can be repeated. I have no idea how safe this is against various cryptanalytic attacks; for all I know there is a way of breaking the scheme that is obvious to more devious minds than mine. Use at your own risk. -- Lambiam Talk 14:53, 2 June 2006 (UTC)
What do you call this type of notation?
or
As far as I can remember, ∗ is always been one of Σ, Π, ∩, ∪, or ∐ (coproduct), but theoretically couldn't it be extended to apply to any binary operation? Or maybe even to any function?
I don't understand why this ubiquitous notation does not seem to have a name.
In statistical process control using control charts, I have noticed that presenters often recommend calculating the standard deviation in a, so to speak, nonstandard way. The recommended procedure is to calculate a mean moving range, i.e. , using a relatively small dataset, and then divide the mean moving range by the magic number 1.128. If you google for " (1.128 and calculate)" and are feeling lucky today, you will find a such a presentation. The number 1.128 is often represented by the symbol d2. Does anybody know the maths behind this non-standard estimator of the standard deviation? -- vibo56 19:00, 1 June 2006 (UTC)
Can anyone help me with the problem below. I am aware that it is a homework question, but that is why I don't want you to answer it! The question is to simplify it and I assume that you have to multiply out the parenthesises:
I obviously tried WP, but couldn't find the right article. Thank you very much. K ilo-Lima| (talk) 20:05, 1 June 2006 (UTC)
PLEASE I WOULD LIKE TO KNOW HOW THE Monte Carlo simulation techniques IS USED to evaluate the impact of DEM error on viewshed analyses.
What kind of substitution should I use? Patchouli 06:18, 2 June 2006 (UTC)
Patchouli 07:17, 2 June 2006 (UTC)
I have a question involving circular motion. Visualise a roller coaster's path. At the start, a straight part of length x, at an angle of 10° above the horizontal exists. A particle rolls down this, and meets an arc of radius 8m sloping downwards, and declines to a straight path 40° below the horizontal. The path is smooth and is only affected by gravity. I have to find the maximum value of x so that the particle stays on the path. I've only ever encountered particles with a mass, and this one has none specified, so I assume it cancels somewhere.
Anyway,
I'll figure stuff out from here.
Thanks. x42bn6 Talk 08:57, 2 June 2006 (UTC)
____ x 10° ˇˇˇˇ----____ ˇˇˇˇˇˇˇˇˇˇˇˇ _--ˇˇˇ--_ /ˇ ˇ\ | 8m |\ | ·<---->| ˇ\ | | ˇ\ \_ _/ 40° ˇ\ ˇ--___--ˇ ˇˇˇˇˇˇˇˇ
Why does this work?
1. First of all, pick the number of times a week that you would like to have chocolate (more than once but less than 10) 2. Multiply this number by 2 (just to be bold) 3. Add 5 4. Multiply it by 50 -- I'll wait while you get the calculator 5. If you have already had your birthday this year add 1756 .... If you haven't, add 1755. 6. Now subtract the four digit year that you were born. You should have a three digit number The first digit of this was your original number (i.e, how many times you want to have chocolate each week). The next two numbers are: YOUR AGE! (Oh YES, it is!!!!!)
I got it from ebaumsworld and it works for me. I find it really weird. Thanks. schyler 13:48, 2 June 2006 (UTC)
no, I put in 3 for how many per week and I'm 14 and I got 313,
1 → | 3 | 2 → | 6 | 3 → | 11 | 4 → | 550 | 5 → | 2306 | 6 → | 314 |
1 → | 3 | 2 → | 6 | 3 → | 11 | 4 → | 550 | 5 → | 2305 | 6 → | 313 |
I have a complex analysis exam coming soon, and I'm not very confident with Laurent series. Suppose I have a complex function f(z) which has a finite number of poles. Is there a general method for finding its Laurent expansion? Admittedly, my knowledge of Laurent series is somewhat limited. I know what they are, but not really how they work. Can anyone help? Maelin 03:12, 3 June 2006 (UTC)
I would like the definition and applications of a voronoid diagram (scatter application). Please put a definition on your web site.
what is the quadratic formula —Preceding unsigned comment added by 69.231.27.28 ( talk • contribs) 04:03, 2006 June 3
How do I search edit areas in Firefox? For example, when I edit a long article and want to find where it links to a specific category, the text entered into the search field seems to be searched for only outside the wikicode. Is there any way to get it straight? Conscious 06:07, 3 June 2006 (UTC)
I have Mathematica 5.0. What is the best way to transform the *.nb to a format that Wikipedia understands.
Given an integer n, what are the tightest bounds on factorial n? More specifically, I want to calculate the number of binary digits required to represent n! for a given n. -- Sundar \ talk \ contribs 10:37, 3 June 2006 (UTC)
Well considering that summation is cheap for computer, for relatively small n you can get a very good estimate by using
Consider a torus, cut a tiny CLOSED piece out on the side. So the piece I cut out is homeomorphic to .
What is the remaining space? My professor tells me I can only see it when i start stretching that hole open 'until my fingers touch on the other side'. However I was born with no 3D mind, I simply do not see it.
It should be an 'easy space involving cylinder(s)' I would like to understand this completely for the understanding of homotopy and homology groups.
Evilbu 11:35, 3 June 2006 (UTC)
Well uhm, what is a handle, my syllabus says every is a handle? The article http://en.wikipedia.org/wiki/Handle_%28mathematics%29 doesn't really help me out right now. Evilbu 12:16, 3 June 2006 (UTC)
I am very confused now. What do you mean, a cylinder attached at its two end circle, you mean take a cylinder, then attach the upper and lower circle? Wouldn't that be a torus? Why would the product of two balls be trivial? What is the union of twice Evilbu 12:44, 3 June 2006 (UTC)
Seems like I know much less than I thought. Is there a precise definition of handle (I am familiar with the language of quotient spaces) In order to make sure we understand each other, I will say a couple of things, and please tell me when you disagree : is the closed disk in two dimensions is the unit circle (it is one dimensional , the (empty,thus 2d)torus, is homeomorphic with the full,thus 3d torus is homeomorphic with
Maybe it would be relevant to say why I want this. I want to find the torus' homology groups, especially the group Now my professor told us to do a Mayer Vietoris trick on the torus, by cutting out a little piece (a disk) . The two spaces I get then, have a 'relatively easy' intersection in my Mayer Vietoris sequence, it is a cylinder, homotopic with a circle, and thus completely known. But what is the other space? Evilbu 15:31, 3 June 2006 (UTC)
Uhm, no I do not know anything of universal coefficient theorem. If it is relevant, we always consider these groups as modules, thus abelian groups. I know I cold do a Mayer Vietoris trick by using two cylinders, who intersection are two disjoint cylinders, then I find everything except Basically I was hoping by doing this cutting out of a little sphere, I would be able to find it in another way. Evilbu 09:47, 4 June 2006 (UTC)
Please help a new small manufacturing company by locating "indirect labor unit cost." We need this for our financial portion of the business plan as required by Small Business Administration. Our leaders, Maasters of Science in Healthcare, for some reason did not include this information. If anyone out there can help, it will greatly appreciated. Our company sews dresses and suits for premature infants and low birth weight infants. The SBA booklet indicates that this "cost" is needed to be included with total production costs.
This question may not be a typical for Wikipedia, but we have really been trying to find this and to date have not been successful.
Can someone give me a simple mathematical forumla sude in civil engineering? It's for a math homework project. Thanks in advance! -- Wizrdwarts 01:38, 4 June 2006 (UTC)
Catenary has a cool formula for suspension bridges... (and that is TYPICAL engineering right?) Oh by the way, you should write formula. Evilbu 10:48, 4 June 2006 (UTC)
Suppose you had the values of 1 to 100. Then, you randomly organized the 100 numbers into 10 groups of 10. One group might contain the numbers 7, 13, 17, 38, 41, 52, 59, 71, 90 and 95 for example. Then, by group, the highest number would be given a corresponding value of 10, the second highest a corresponding value of 9, and so on. Then, the process is repeated, and any value earned is added to the last value earned. For example, the number 100 will always be given a value of 10 (because it is always the highest number out of 100), so after 3 random "draws," its corresponding value would be 30. Likewise, the number 1 would have a value of 3 after 3 "draws." My question is: how many random "draws" would it take so that all the numbers were in numerical order based on their values. Likewise, how many random "draws" would it take so that less than 10 numbers were not in correct placement when organized by values. I understand that this question is confusing (and it is quite hard to word), so if you have any questions as to what I mean, then please ask and I will update and clarify accordingly. Thank you in advance for all of your help. - Zepheus 02:55, 4 June 2006 (UTC)
(1-10) (11-20) (21-30) ... (91-100) (1,11,21,31,...) (2,12,...) (3,13,...) ... (9,19,...) ... (10 times) ... (1,11,21,31,...) (2,12,...) (3,13,...) ... (9,19,...)
Some thoughts on the convergence of the order. Consider a random variable , the rank of number k in a random draw. Denote . Denote by the event that the numbers k and k+1 are in different groups, its probability is . Given , has the same distribution as , and is symmetric with respect to 0 ( for x>0), thus . With probability 1/10 the numbers k and k+1 are in the same group (, complementary to ) and and . That is,
Besides, we have
After realization of n draws, the numbers 1,...100 have the correct order if
It is known than in distribution so the convergence to the correct order should be expected. The questions arise whether the r.v. are independent of each other, and for which smallest n the event occurs the first time, and what is the distribution of such n. ( Igny 22:46, 4 June 2006 (UTC))
These mathematical functions are getting crazy. I wish I could decipher them. I'll definitely archive this page. One more question, the first answer I receive was that 11 draws would be sufficient. The next answer was that roughly 2,050 draws would be needed. How are these related? Also, what is the rough estimate for the number of draws needed for less than, say, 10 mistakes. - Zepheus 19:09, 5 June 2006 (UTC)
Okay. I understand now. Thanks for the update, and all of your hard work. - Zepheus 21:16, 5 June 2006 (UTC)
Can anyone recommend me loudspeakers for an integrated sound card (asus a7v8x-x) with a good quality/price ratio? thanks.
Hi,
I have yet again a topology inspired question. First of all though I would like to express my gratitude for the many people who have helped me here.
Right now I mostly receive from Wikipedia being a student in exams, but I have and I will again give to the community myself:)
I am confused about http://en.wikipedia.org/wiki/Free_product_with_amalgamation
Suppose I take a free product of the groups and the article states it should give me a free group on two generators. Now the article on free groups it links to says that free groups and free abelian groups are not the same. There goes my hope that it would be
but wait! , later that article says it is a coproduct of two groups in the categorical sense. But I was thought in my algebra class that for Rmodules, and thus also abelian groups (as they are the same as \mathbb{Z} modules ), simply taking the outer direct sum of two modules should do just fine to give you a categorical coproduct.
So what is going on, can anyone point out the difference between coproduct and free product. What am I doing wrong?
This confusion has led me to believe than 'eight' or an 'infinity symbol' has fundamental (homopoty) group}.
Thanks, Evilbu 14:53, 4 June 2006 (UTC)
But that is bad for me! So you are saying : free product of two groups is NOT the same as coproduct?
Evilbu
17:05, 4 June 2006 (UTC)
Oh yes, I see, I think I have made a serious mistake in assuming something. I was seeing the abelian groups as a subcategory of the group category. I cannot take some abelian groups, take the free product (defined in the categorical sense) and assume it will still be that in the bigger category right? Evilbu 20:58, 4 June 2006 (UTC)
I know how easy it is to fall off a bike while not moving - I also know that it's harder to turn the wheel when I am in motion. I've had a look at angular momentum and related topics and I can't figure why a rotating bike wheel is harder to turn from its line of motion than a stationery one. Any help please? Anand 18:54, 4 June 2006 (UTC)
I just started this article. If anyone believes they can add anything more to it, even one more sentence, go right ahead. — BRIAN 0918 • 2006-06-05 05:52
A question about poles. Consider a function of this form:
Will it have a pole at z = a? A removeable singularity? Or some other form of oddness?
Maelin
06:26, 5 June 2006 (UTC)
Several of my measuring tapes have a measure mark that is a small black diamond shape. There are five of them for every eight feet or 19 1/5 inches for each mark. What is this measure? Sincerely
Its purpose is to allow carpenters to divide 8 feet exactly in five. See this page and this page (scroll down to diamond) for documentation. There has been a dispute on the Wikipedia where a user claimed it to be an "English cubit", but this is apparently not correct. -- vibo56 09:45, 5 June 2006 (UTC)
So the black diamond is a carpenter's mark! Very interesting, I'd been supposing it was some foreign unit of measurement. I was guessing Chinese!
Thanks very much. Albert J. hoch Jr.
What does the following integral evaluate to:
where is the Dirac delta function and H(x) is the Heaviside step function.
What about the following:
If these do not exist, what are reasonable approximations to them I can make? deeptrivia ( talk) 18:27, 5 June 2006 (UTC)
Thanks lethe. Is it terribly unsafe to assume, for engineering purposes, that H(0) = 0.5, while integrating these? deeptrivia ( talk) 21:42, 5 June 2006 (UTC)
it gives:
The limit of this expression as epsilon --> 0 is undefined. However, as an engineering approximation, we can assume to be something small, like 1e-24, and then and , and so the integral evaluates to 1. Is there any flaw in this reasoning? I'm asking because there's a significant thing happening between -1e-24 and 1e-24, which will be ignored by this assumption. Another thing is, if I were doing this integration from, say -1 to 1, then, say you pointed out I won't have cared about values at finite points. But here, the integration has to be done in a range that encloses 0 and is as small as can be imagined, so the value at 0 might have a significant effect. Regards, deeptrivia ( talk) 01:14, 6 June 2006 (UTC)
The limit of
as epsilon --> 0 is undefined according to Maple itself (using the 'limit' function). The first approach I followed was the one proposed by Jitse Niesen, but I can't remember any more why I gave up on it. Anyway, these equation arise from a nonlinear treatment of point loads and moments at various points on a flexible beam with discontinuities in cross sectional area (like a stepped beam.) I am using heaviside functions to model steps in areas, and dirac functions to model point loads and moments. Any suggestions appropriate to this situation? Thanks. deeptrivia ( talk) 04:18, 6 June 2006 (UTC)
If you use the definition of the Riemann-Stieltjes integral, then the first integral is equivalent to
On the other hand, . Conscious 05:57, 6 June 2006 (UTC)
Hi,
consider a cylinder thus
I am still working on that torus, and I thought, this would be handy :
suppose I have a loop ,so let's say a path
and another , a path
Are these two loops in the same homology class, I mean, is their difference, in an element of the image of
-- Evilbu 20:01, 5 June 2006 (UTC)
Thanks, yet I'm sorry but I don't completely get it.
Please be very clear in what you mean : homotopy between paths, or homotopy between continuous maps in general.
Here was my idea : a 'push up u' of (b-a) is a continuous map from the cylinder to the cylinder, homotopic with the identity
this means
and thus
A little weird I think. Why would a homotopy between those two points suffice? And what kind of homotopy do you speak, usually they mean with 'homotopy between two paths' : the homotopy fixes begin and end point all the time, which cannot be the case here as both are even disjoint.
Evilbu
21:42, 5 June 2006 (UTC)
Thanks everyone, it's a bit hard to understand that all completely. But I surely would like to know this : lethe, you wrote that p-q is the boundary of a segment. But I was taught that you need linear combinations (over the integers) of 2-simplices (those are maps from a triangle in the plane to your space). How would you proceed? Evilbu 08:15, 6 June 2006 (UTC)
tl | T | tr | ||||
● | ⟵ | ● | ||||
L | ↓ | ↘ | ↑ | R | ||
● | ⟶ | ● | ||||
bl | B | br |
T = (tr, tl) | B = (bl, br) | L = (tl, bl) | R = (br, tr) | D = (tl, br) |
∂T = tl − tr | ∂B = br − bl | ∂L = bl − tl | ∂R = tr − br | ∂D = br − tl |
∂σ1 = D + R + T | ∂σ2 = L + B − D | ||||||||
|
|
∂σ1 = D − L + T | ∂σ2 = L + B − D |
∂(σ1+σ2) = T + B |
There is a highly useful formula which looks like the sine rule, ie something/something = something/something = something/something but I've completely forgot it. I believe terms like arc length, area, theta etc were included in it but I can't remember the other ones, nor can I remember the order. Thanks, Matt. —Preceding unsigned comment added by 80.229.237.12 ( talk • contribs) 19:39, 5 June 2006
What the article didn't mention(can anyone expand the radian article?) is however the formula of sector area in radian terms. Since the area ratio between the sector and the full circle is the same as the ratio between their radian measures, we have
I'm trying to implement IDEA in assembly language on a 386, and I'm having trouble because it was optimized for 16-bit processors. I want to be able to concatenate two 16-bit numbers to multiply mod and then separate them later, but I'm having trouble with it. I've tried using and but neither lets me extract just the multiplications I want and it's all mixed up. -- Zemyla t 21:05, 5 June 2006 (UTC)
I assure you this is not homework, just a question from someone who hasn't taken geometry since high school and did almost nothing with three dimensional shapes, at that.
Let's say I have a truncated icosahedron that should fit into a sphere an inner diameter of 150 cm. How long should each of the vertices be? I'm sure this is probably easy for someone to calculate given all of those wonderful symbols on the icosahedron page but I'm totally baffled by them.
Many thanks. -- Fastfission 22:48, 5 June 2006 (UTC)
I have to do some cutting and splicing of audio files in WAV format, but I don't seem to have suitable software handy. Does anyone know of any freeware which might do the job and run under Windows XP? —Preceding unsigned comment added by Physchim62 ( talk • contribs) 19:00, 6 June 2006
After i have played around with the number 9 i noticed that 9 will always end up as 9.
For example:
9x9 = 81 (8 and 1) 8+1=9
9x15 = 135 (1 and 3 and 5) 1+3+5=9
9x265 = 2385 (2 and 3 and 8 and 5) 2+3+8+5=18 (1 and 8) 1+8=9
9x996633 = 8969697 (8 and 9 and 6 and 9 and 6 and 9 and 7) 8+9+6+9+6+9+7=54 (5 and 4) 5+4=9
This you can do with any random number. 9x? = 9
So my question is: When was this noticed the first time and who noticed it?
-Randi Hermansen, Denmark
Does any one have any information on how the vast tables of logarithms were calculated. Clearly, it is not a simple task or tables would not have been necessary. 68.6.85.167 21:52, 29 May 2006 (UTC)
I just wanted to say thanks to all of the contributors here. The people here are really knowledgable and have help satiate my intellectual curosity on different occasions. Mayor Westfall 20:21, 6 June 2006 (UTC)
I'm learning recurrence relations in school and I frequently come across problems involving finding the number of generations needed for the recurrence relation to have an answer twice its original value. So basically we are asked to find n when:
The method that is taught in school is to go through each generation by iteration and eventually finding n when you find that un has grown to twice the size of u0. However, the obviously easier method is to use the equation:
Is there a similar shortcut when the recurrence relation is instead defined as this?:
I have tried working it out by firstly expanding each iteration:
From this the whole series can be expressed as:
We can see the bracketed part of the equation is actually a geometric series, with the starting value b, ratio a and number of terms n (not n−1 as the starting value counts as one term). Also, the number of terms appearing in the geometric series seems to equal the number of iterations in the recurrence relation. Therefore we can use the equation for the sum of the geometric series:
Where s is the starting term, r is the ratio and n is the number of terms. Thus, substituting into the recurrence relation:
Unfortunately at this point I hit a dead end because I'm unable to change the subject to n. Is this along the right lines or is there a completely different method? ----
★Ukdragon37★
talk
20:27, 6 June 2006 (UTC)
hello, i'm a student of physics taking an engineering course. can anyone give some intuition on the following:
the fourier transform of a sine wave of frequency w extracts the frequency w. but a fourier transform of a delta function (which has no width (in the time domain) and so no duration) extracts all frequencies.
my question is, how can a delta function accommodate all frequencies?
thanks -crj
ha! it makes sense that higher frequencies are needed to produce more abrupt transitions. thank you all for taking the time to answer. (incidentally, not sure how the answer sech(1⁄A ω√π⁄2) was obtained. i searched through my signal analysis books, an engineering mathematical handbook, and a book on mathematical methods of physics but could not find the result. i even tried to get this result using Maple, but all i get in return is my original input!)
Apple has released
Boot Camp public Beta, which will be included in
Mac OS X v10.5.
Question: Will
Windows Vista also be able to run in a Mac usinq Boot Camp? --
Alexignatiou
08:49, 7 June 2006 (UTC)
Hello,
I am quite unsure about something my professor told me.
Let be open, and let f be a function in , unless I am really mistaking, that just means that f is defined in , and that is can be continuously derived p times
Now he told me if I just define an extension by making it zero outside \Omega , I get an function, locally integrable thus : integrable over every compactum.
Either I got my definitions incorrect, or this is incorrect : what about in ?
Evilbu 10:14, 7 June 2006 (UTC)
Hm, I don't understand, is that true? What about and That function can be extended to a function, but it certainly will never be integrable?? So what is your definition in your opinion? I am guessing you would go for this then :
and and f can be derived continuously p times
Evilbu 17:10, 7 June 2006 (UTC)
Thanks, but then what is your definition exactly of ? Evilbu 19:52, 7 June 2006 (UTC)
If I install Ubuntu (64-bit linux) on my computer with AMD64 3200+ should I expect an increase in performance? -- Username132 ( talk) 13:22, 7 June 2006 (UTC)
I don't want to pay for hardware capable of more than I need. I want to buy a new system disk and the way I see it, I've a few options; a) buy two WD raptors and put into RAID-0 configuration b) buy two budget HDs and put into RAID-0 c) buy one raptor d) buy one budget drive
When loading the OS for example, is the speed of the HD a bottleneck for an AMD64 3200+ system with Corsair value RAM? And what games really benefit from 300 Mb/s data transfer to and from your HD? I would have thought the graphics card would be the bottleneck in any system with an old ATA-100 - I mean most important, immediately required information will be in the RAM, wont it? —The preceding unsigned comment was added by Username132 ( talk • contribs) .
If I roll three six-sided dice (3d6) and only take the median roll (not the mean or average), what kind of bell curve or distribution odds would it give me for the result 1 to 6?
If I roll two 20-sided dice (2d20) and only look at the higher result of the two, what is the average result I will get? What about 3d20 and only look at the highest die? 4d20 etc. up to 16d20...?-- Sonjaaa 11:43, 8 June 2006 (UTC)
1 : 2/27 2 : 5/27 3 : 13/54 4 : 13/54 5 : 5/27 6 : 2/27
It is quite straightforward to use JavaScript to return today's date, but how would you go about getting it to return tomorrow's date, or the date in ten days' time? — Gareth Hughes 14:18, 8 June 2006 (UTC)
Not long ago I purchased an "Introductory" copy of Microsoft's Visual C++ on eBay. Since I have not programed in C since 1984 I was really surprised at how far it looked like C had come. However the "Introductory" version will not compile programs that worked great back in 1984 and even when a console program is written that compiles with no errors it stops and says that because it is an "Introductory" version that I can't make an execute file. I need another compiler but would like to avoid giving away any more of my hard earned money to Microsoft. What C++ compiler do you recommend? ... IMHO ( Talk) 17:12, 8 June 2006 (UTC)
... IMHO ( Talk) 20:42, 8 June 2006 (UTC)
I have a very strange problem with Matlab's bvp4c. Hopefully, someone here would have some idea what's going wrong. I am solving a 30-variable boundary value problem, and I know that for certain inputs, a particular variable u3 must be 0 everywhere. bvp4c returns the values of variables y(x), as well as their derivatives yp(x). The derivative of u3 in the result is always zero (sth like 1e-17 to be precise, and x ranges from 0 to 1), so that looks good. But the value of u3 is varying a lot (instead of staying 0, it goes smoothly, but not linearly to 0.9). Doesn't it clearly mean there's a bug in matlab's bvp4c? What else could be the problem? deeptrivia ( talk) 18:10, 8 June 2006 (UTC)
Suppose we have a large symmetric matrix which can be partitioned into smaller blocks matricies. These smaller blocks happen to be symmetric too. Suppose further, that we are given all the eigenvalues of each of these blocks. Is there a way to infer the eigenvalues of the entire original matrix easily? -- HappyCamper 19:09, 8 June 2006 (UTC)
this is somewhat elementary, and perhaps you know this already. but in the special case that all your blocks are scalar multiples of each other, then it is a Kronecker product and you can get the eigenvalues of the big matrix. Mct mht 00:39, 15 June 2006 (UTC)
Has there been any research done into extending taxicab geometry into 3D space? -- Tuvwxyz 21:11, 9 June 2006 (UTC)
My stepdad ( a landscaper) recently asked me how to find the area of... I guess the best way to name it is a sector of a oval. There are to radii (?) that meet at a right angle and one is 10 feet and the other 8 feet. They are connected by an arc that is ≈17 feet. How would I go about finding the area of this shape? Thanks. schyler 01:43, 10 June 2006 (UTC)
I tryed to translate the Mathematica .nb-files to TEX- and Mathmarkup- files. Wikipedia did not understand these. The only way was to translate to HTML. It consisted of mainly .gif images, which i had to translate to .png using GIMP . If i used small fonts they were unreadable. I think this is my only article, Collocation polynomial,so i am not interested to become spesialist in TEX or mathmarkup. Now i am going to holiday. If someone has time and possibility to cleanup the article, please do. -- penman 05:08, 10 June 2006 (UTC)
Yes, this is assignment work, but I have done most of the work. We are given the equation of the basic hyperbola x^2/a^2 + y^2/b^2 = 1, and are asked to prove that PF' - PF = 2a, where P(x,y) is a variable point on the hyperbola, and F' and F are the foci at (-c,0) and (c,0) respectively. I can prove this by taking the basic equation above, and manipulating it to show sqrt((x+c)^2+y^2) - sqrt((x-c)^2+y^2) = 2a. However, I find I need to substitute c^2-a^2 for b^2 in order to do this. In other words, I need to prove c^2 = a^2 + b^2. Looking around on the internet, because most people start with the difference of the distances (sqrt((x+c)^2+y^2) - sqrt((x-c)^2+y^2) = 2a) and use that to find x^2/a^2 + y^2/b^2 = 1, they simply define b as being sqrt(c^2-a^2). Obviously, since I am working from the base equation and using it to find the difference of the distances, it would not be right to just replace b^2 with c^2-a^2 without providing justification. Can it be done? Or is my method too complicated?
Hi there,
Working on a publication using a lot of information burned onto a DVD by a friend of mine. But I keep getting cyclic redundancy checks. The article here is rather useful (but rather hefty)... what I need to know, though, is if there's a way to say "just skip that bit and keep copying, please" to the computer. If it's just a little little bit of data that the computer can't read, can't I just hop over that bit and see if the file's still basically okay later? If one pixel of one photo is FUBAR, that doesn't change that much for me. -- MattShepherd 12:20, 10 June 2006 (UTC)
dd conv=sync,noerror
. However, you may still end up losing entire disk blocks (a couple of kilobytes) for even minor scratches. It's the best solution I know of, though. —
Ilmari Karonen (
talk)
00:05, 11 June 2006 (UTC)
dd conv=sync,noerror
, though the page suggests that it may be somewhat faster in certain situations. —
Ilmari Karonen (
talk)
13:41, 11 June 2006 (UTC)coe=3
setting — except that the feature is apparently not supported by CD/DVD drives. —
Ilmari Karonen (
talk)
13:50, 11 June 2006 (UTC)
Suppose F is a set, is a binary relation on F, and for each a ∈ F there is b ∈ F such that (a, b) ∈ R. I am interested in recursively constructing a sequence (ai)i ≥ 0 such that for every non-negative integer i, (ai, ai+1) ∈ R. It is easy to show that finite sequences of this type with arbitrary length exist; However, I am having difficulties showing that an infinite sequence of this type exists. That is, of course, unless I am using the axiom of choice, in which case the proof seems straightforward. My question is, is the possibility of this construction provable with ZF, or is the axiom of choice (or a weaker form) necessary? Is it still necessary if it is also known that F is countable? I strongly believe that the answers are, respectively, yes and no, but I just want to make sure. -- Meni Rosenfeld ( talk) 17:37, 10 June 2006 (UTC)
Great, thanks! -- Meni Rosenfeld ( talk) 19:18, 10 June 2006 (UTC)
Hi,
let be open and nonvoid in
let
by that I mean and on every compactum it is integrable
suppose now that for every
(this means w is infinitely differentiable on all of but it has a compact support in )
show that f is almost everywhere zero
Now I have worked on this, and came up with the idea of convolving with an approximation of unity.
But then I got confused, what exactly to do with this open I have to respect the confinements of my domain right? Thanks,
Evilbu 19:56, 10 June 2006 (UTC)
Yes I see what you mean, but if f was continouos and nonzero at some point p, it could make it strictly positive or negative in an open ball around it, and then a proper w can quite easily be found, but what to do here, a set with positive measure, so many cases? Evilbu 08:52, 11 June 2006 (UTC)
Well I'll be honest, it's a proof from a syllabus that me and my costudents dispute. The proof works with convolving, but seems to show little regard for necessary analytic subtleties (like discontinuity even). Evilbu 17:00, 11 June 2006 (UTC)
I need to create an array that can hold 10 million integer numbers and fill it with random numbers ranging from 1 million to 10 million (minus one), When it is filled I need to write the index and contents to a file. I know how to generate random numbers in MASM and how to write from memory to a file using debug but I need to put them together in a MASM program. Anyone have a demo or example? ... IMHO ( Talk) 00:52, 11 June 2006 (UTC)
Yes this information helps. Thanks. However, my goal in part here is to learn (or relearn) MASM. Back in the late '60's and early '70's assembly language was quit straight forward (and can still be that straight forward using the command line DEBUG command). Where I am having trouble currently is with INCLUDEs. Irvine32.inc in particular so I am trying to avoid even the use of INCLUDEs and do this (if possible) using only a DEBUG script. Don't get me wrong I have spent ALL of my programming career writing in high level language simply so that I could get far more work done but now my goal is to go back through some of the programs I have written in a high level language like Visual Basic and convert what ever I can to concise assembler or machine code which might help bridge the gap between Windows and Linux whereas a program written in C++ for Linux (source code) may otherwise find difficulty (after it is compiled under any version of Window's C++) to run. What I need specifically is to 1.) know how to create and expand a single dimension integer array with the above size. Therefore I need help with both the memory management and indexing, 2.) Although I can make random numbers fall into any range in Visual Basic I'm not sure about doing this in assembler, 3.) I also need help in writing the array contents and index to a file since even though I know how to write something at a particular location in memory to a file using DEBUG and how to write an array to a file using Visual Basic it has been a long, long time since I used assembler way back in the early '70's. Your suggestion to try writing in C and then doing a compile to study the output is a good and logical one but my thinking is that by the time I get back into C so that I can write such a snippet of a program that I could have already learned how to do it using MASM. Even still it is not an unreasonable or bad idea. Any code examples would lend to my effort and be appreciated. Thanks. ... IMHO ( Talk) 14:58, 11 June 2006 (UTC)
I followed your suggestion to look at the disassembled output of the following C++ code and was shocked to find that while the .exe file was only 155,000 bytes the disassembled listing is over 3 million bytes long.
#include <stdio.h> #include <stdlib.h> main() { printf("RAND_MAX = %u\n", RAND_MAX); }
I think I need to stick with the original plan. ... IMHO ( Talk) 15:43, 11 June 2006 (UTC)
E:\src\wikipedia\masm_test>cl /Fa /c /I "c:\Programfiler\Microsoft Visual Studio\VC98\Include" main.c Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 12.00.8804 for 80x86 Copyright (C) Microsoft Corp 1984-1998. All rights reserved. main.c E:\src\wikipedia\masm_test>dir *.asm Volumet i stasjon E er ARBEID Volumserienummeret er 4293-94FF Innhold i E:\src\wikipedia\masm_test 13.06.2006 19:23 2 292 main.asm
Okay, finally got it! The thing that was messing up the command line compile under VC++ v6 Intro seems to have been a "using namespace std;" line (although oddly enough it has to be removed when the contents of an array variable are incremented but required when the same variable is only assigned a value). It looks like VC++ Express 2005 has the same settings function in the GUI but I have not yet been able to figure out and follow the procedure to get it to work. Its command line .asm intruction might also work now but I do not have time right now to test it. Thanks for all of the detailed suggestions and for helping to make the Wikipedia more than I ever dreamed it would be. Thanks. ... IMHO ( Talk) 21:35, 15 June 2006 (UTC)
what is html???
how would i do these problems, i have an exam tomorrow and i would love an answer soon:
b. x/(2x+7)=(x-5)/(x+1) and c. [(x-1)/(x+1)]-[2x/(x-1)]=-1
i have no idea how to approach this problem the directions say: Solve each equation. -- Boyofsteel999 01:09, 12 June 2006 (UTC)
1. Multiply by the terms on the denominator (ie. the bottom). For example, if you had the equation you multiply by the and terms, giving you .
2. Solve the problem as you would any kind of quadration equation - gather it into a normal quadratic form, and either factorise or use the quadratic formula. In this case, we first get , which reduces to , the solutions of which (using the quadratic formula) are .
Technically there's a third step - make sure that the solutions you get are not going to make the denominators zero - but a. this shouldn't happen anyway, and b. once you get to complex analysis you treat these solutions that aren't really solutions as solutions that just aren't explained clearly. Confusing Manifestation 02:15, 12 June 2006 (UTC)
The inverse limit of the cyclic groups Z/pnZ for p a prime gives you the group of p-adic integers (a group about which I know little). It seems to me that the collection of all finite cyclic groups also forms a direct system of groups over the directed set of natural numbers ordered (dually) by divisibility. Thus shouldn't there be an inverse limit of this system as well? What is it? Probably it's just Z, right? - lethe talk + 06:10, 12 June 2006 (UTC)
4 | 8 | 12 | 16 | 20 | 24 | 28 | 32 | 36 | 40 | 44 | 48 | ... |
1 | 1 | 9 | 1 | 5 | 9 | 21 | 1 | 9 | 25 | 33 | 33 | ... |
In sentential logic, it seems to me that the set of well-formed formulas (wffs) may profitably be thought of as a set with an algebraic structure. One has a set of sentence variables, and one may perform various operations on the sentence variables; usually disjunction, conjunction, negation, and implication. The sets is then some sort of free algebraic structure in these operations on the set of sentence symbols. Another algebraic structure with these operations is the set {0,1} (with the obvious definitions of the operations), and a truth assignment may then be defined as a homomorphism of this kind of structure from the free structure of wffs to {0,1}, which is used to determine an equivalence relation called tautology. The Lindenbaum algebra is the quotient of this free structure by this equivalence relation and is a Boolean algebra.
This description in terms of algebraic language differs in flavor a bit from the way I was taught mathematical logic (from Enderton), and I have some questions. It seems that this algebraic structure is completely free; it doesn't satisfy any axioms. So I guess it's not a very interesting structure. Is this a standard construction? Does it have a name? I've been using the name "free pre-Boolean algebra", so that a truth assignment is pre-Boolean algebra homomorphism.
I like the algebraic description here, one reason being that it gives a concise way of defining semantic entailment. On the other hand, I don't see any nice algebraic way of describing syntactical entailment. Is there one? Can I describe modus ponens as an algebraic operation in this structure? - lethe talk + 06:10, 12 June 2006 (UTC)
First I would like to state that this is not for homework purposes, merely some discrepancy with a textbook we discovered recently. We've experimented with combining cubes in a variety of completely different formations (that is, excluding replicas via reflection or any other direct transformation), and the particular one we decided to do on that occasion was 4. However while we could find only seven different combinations, the textbook insisted that there was eight. Can anyone help me to either confirm the textbook answer, or our own answer, and if possible state a brief "proof" of why a certain answer is so.
Also, the reason that we were experimenting was because we were trying to develop a general algebraic processes to find the number of combinations as a function of the number of identical cubes. If anyone can possibly give any directions towards this search at all it would also be helpful and greatly appreciated. LCS
I saw a question on the science page that bugged me and made me think of the following quesiton:
Say you have two moths flying toward each other carrying a light source. They are attracted to light 10 meters away, and their parallel paths are separated by 5 m, would they crash into each other? ...Sounds like this would make a good text book calculus question. Anyone have an answer? XM 16:50, 12 June 2006 (UTC)
Once they detect the light, they are pulled towards the light at the same speed they are traveling--(XM) but too lazy to sign in.
I am making an applet at a certain point in this applet i clear a JPanel with the removeAll(), after i have done this it seems as thought it is impossible to add anything to this JPanel again.
Is it possible to add to a JPanel after having used removeAll(), or how would i go about placing new content to the same JPanel while taking off the content thats already there Thank you very much
-- 70.28.2.95 19:37, 12 June 2006 (UTC)
I tried using validate() but it still wont update, the JPanel stays blank. I tried invoking it both before and after adding to my JPanel but the results were the same -- 70.28.2.95 00:47, 13 June 2006 (UTC)
validating the parent container and all the components seems to have done the trick. Thanks alot for your time. -- 70.28.2.95 19:00, 13 June 2006 (UTC)
For the WikiGeometers out there...I wonder if you could help me identify these two solids by name? I'd like to include them in articles which might be lacking in illustrative images...Thanks! -- HappyCamper 21:42, 12 June 2006 (UTC)
The one on the left is impossible to make unless you are talking about spherical geometry. As for the one on the right, I have no idea. Yanwen 00:21, 14 June 2006 (UTC)
I would like to say thanks to the editors of this project. I have learned more in a few weeks of perusing the portals in the math section than I did all through my engineering curriculum. Absolutely fascinating stuff, and very well organized. In my mind, mathematics is learned best by a first organizing the general ideas of math, then discovering how they are sometimes connected. This thorough organization has been a hugely interesting, and, I suspect, many others who just read but don't say anything. Anyway, sometimes simple thanks justifies long hours of effort, I've found. I hope it does for all of you. Denmen 02:33, 13 June 2006 (UTC)
How can a person measure the height of a tall object such as a telephone pole, a tree, a tall building, etc? —Preceding unsigned comment added by Stockard ( talk • contribs) 20:08, 12 June 2006 (UTC)
Can someone tell me what ΔQ% means? Groc 10:39, 13 June 2006 (UTC)
I have a set of N points (xi,yi). I want to find out the radius and subtended angle of the circular arc that can best approximate those points and the least square error in this approximation. How can I do this? Thanks. deeptrivia ( talk) 19:47, 13 June 2006 (UTC)
I've been fiddling around with primes for a bit, and I found a property that I've never heard of before. I'd like to know if it already exists, or if I'm the first to find it. Given a prime P, the product of all primes less than P is A. If a prime N<A can be found that is close to A (meaning A-N<P2), there is a corresponding prime number at A-N. Of course, this can't break any records, since it looks down for primes instead of up, and can only find new primes between P and P2, and then only if there happens to be a prime known between A and A-P2, but still. Anyone heard of it? Black Carrot 22:48, 13 June 2006 (UTC)
I don't think I want to bet, but I'm curious about the way the odds work. Currently at an online betting site, the odds for the first five teams are:
Brazil 4.1 England 8.4 Argentina 8.6 Germany 9.6 Italy 12
Lets say I were to place my bets so I placed $1 on Brazil and $.50 on each of the other four. Am I right in thinking I'm guaranteed to win something if any of the first five win? Likewise, would there be some way to pick my amounts so I'm guaranteed to win something if any of the first ten win? Finally, am I right in thinking that statistically, even doing this, my expected wins should be zero overall (if the odds are fair and accurate), as the pennies I win when the top teams win would be exactly balanced out by the dollars I'd lose when one of the underdogs won? (obviously there are also fees to pay, I assume, but I'm not counting that). — Asbestos | Talk (RFC) 14:01, 14 June 2006 (UTC)
If x is lognormal distributed how is s=s0*exp(x) distributed?
A first-year maths lecturer last year gave us a delightful little insight into where our progressively less intuitive number sets come from. We start with the positive integers, the normal, every day counting numbers. But then we have no solution x for equations like 1 + x = 1. So we need another number, and enter stage left, zero. But we still have no solution for equations like 3 + x = 2. So we need more numbers, and lo, the negative integers give us the complete set of integers. But now we have no solution for equations like 2 * x = 1, and again, we need more numbers, so we get the rationals. Then equations like x * x = 2 yield the irrationals (giving us the set of reals) and if we expand our number set one more time to solve x * x = -1, here we are finally with the complex numbers.
But is that as far as we need to go? Are there any equations like this that we still can't solve, that lead us to extending our number set yet further? Is this where quaternions, octernions et al become needed (I've not read much on them, I admit) , or are they just useful extensions of the concept of complex numbers that have nifty results for physicists? I've played with complex numbers idly while thinking about this but I can't think of any problems left. Are complex numbers finally the end? - Maelin 15:26, 14 June 2006 (UTC)
hello, i hope i am looking in the right section. what is archetypal systems analysis? also i found it as archetypal social systems analysis. thank you very much for you time. -- Marina s 19:12, 14 June 2006 (UTC)
Recently I had the idea of somehow creating a shell extension similar to Microsoft's . ZIP CompressedFolder extension that would enable users to browse through a game archive file. It would handle the game archive files almost the same way as . ZIP files are handled (with shell menu items and being able to open the file and browse through as though it were a folder). Is this possible? If so, how would I go about doing it? What language would be best for this project? I know C#, some C++, and Visual Basic.
Any help, comments, or input on this would be greatly appreciated.
-- Kasimov 19:14, 14 June 2006 (UTC)
It's the Halo/Halo 2 .map format. -- Kasimov 12:21, 15 June 2006 (UTC)
Alright, I don't know if this is enough information but here's some that could be helpful:
The file itself is divided into 4 major sections:
Header |
BSP(s) |
Raw Data |
Tag Index and Meta |
The header is uncompressed and is always 2048 bytes. However, the rest of the file is zip compressed with zLib.
Now, I figured since it's compressed with zlib that would make it easier to make a shell extension, right?
I hope that's enough information, because really it would be pointless for me to type here the entire structure of the file. If you're looking for a complete breakdown of it then visit these two pages: Page #1 Page #2.
Thanks -- Kasimov 13:37, 15 June 2006 (UTC)
Last night a friend and I got into a dispute. In a multi-choice exam with 4 choices (e.g A/B/C/D), where the answers are randomly selected among the 4 possibilities (so for any one question, a random guess at the answer has a 0.25 chance of being correct), what is the best strategy if you have to guess at an answer?
She said that sticking with one letter (e.g. Always guess "A") gives a 0.25 chance of getting the right answer, BUT that choosing at random between two letters (e.g. random guess between "A" or "B") gives a 0.125 (1/8) chance of being right instead of 1/4. Her reasoning: First there is a 0.5 choice between A and B, and then a 0.25 chance of being right. 0.25*0.5=0.125.
I'm sure that's only correct if the real answer is always the same letter.
I think that regardless of whether you guess randomly between A - D, or any two choices, or stick with just one, your chances of being right approach 0.25 in all 3 cases. Because of you always choose A, on average the answer will be A 25% of the time. If you guess randomly between say, A and B, on average each letter will be right 12.5% of the time, and 12.5+12.5=25% (because while A is correct 25% of the time, by choosing between 2 letters the number of A's chosen has been halved. Of course, this also applys to the choice of B, thus the total proportion of right answers is still 25%). Increase the guess to between ABC and D, we get 6.25*4=25%.
Who is correct here?-- inks T 00:28, 15 June 2006 (UTC)
I'm off to college this fall, to major in Computer Science. I thought it would probably be a good idea to get a laptop, so, hearing that ThinkPad hardware is well-supported by Linux, I bought a very nice ThinkPad. I want to dual-boot windows and linux.
I've looked into Linux in the past (and even tried to install Slackware, though I was unable to resize my Windows partition so I gave up) and I've decided on SUSE Linux, primarily because of the easy setup (especially in partitioning) and the focus on ease-of-use.
I have three questions:
1) Which desktop envoronment should I choose, KDE or Gnome? I've had a pretty good experience with KDE trying out Knoppix, but I want to know if I'm really missing out on good stuff in Gnome. Can someone give me a comparison feature-by-feature of what they like about each? Which is used in this video?
2) Will YaST automatically configure my boot menu to dual-boot with windows if it detects OEM Windows XP installed, or am I just going to be stuck with Linux until I can figure out LILO or GRUB?
3) When I upgrade to Vista this fall, will there be any problem getting it to stay in the Windows partition and keeping it from taking over the whole hard drive when it installs? Will I have to rewrite the boot settings, or will Vista do this for me? Or will it rewrite the entire record and take out Linux? In that case, how do I modify it from within Vista to allow access to Linux again?
-- Froth 01:46, 15 June 2006 (UTC)
taxonomy of real numbers
In Mozilla Firefox, is it possible to install the DOM inspector after you've already installed the browser earlier without it? I didn't install DOM inspector because I thought I wouldn't need it, but now it looks like I do, and would like to avoid completely reinstalling and losing bookmarks, extensions and history info in the process. - 131.211.210.12 11:59, 15 June 2006 (UTC)
Me and all my friends cannot get this one. It seems easy enough but there's always a part where we can't get any further..
2x = (x+1)(ln10)/lne
What is x???? —Preceding unsigned comment added by Gelo3 ( talk • contribs) 13:07, 2006 June 15
This ISN'T homework, so PLEASE stop making assumptions. This was a question from a past exam paper I found on the internet for study. 220.239.228.252 14:43, 15 June 2006 (UTC)
Read this :
http://en.wikipedia.org/wiki/Logarithm#Other_notations
Evilbu
15:44, 15 June 2006 (UTC)
I am feeling very daft, as I can't seem to figure this one out and I hope that someone smarter (and more awake!) than me will be able to help.
I scanned in a photo using my scanner, it returned a 150kB file. All well and good. I open it (in Paintshop, if that makes a difference), find out it's sideways, rotate it 90°, save and close. Imagine my surprise when the same file is now suddenly 750kB! What in the world is going on - I just rotated the image, surely it contains the same amount of information?
My guess (after much reading through JPG) is that my scanner is sending me a JPG which is already compressed somewhat, but when Paintshop saves it at 'no compression' the filesize obviously increases. Does this make sense? Or do you suspect something else may be at work?
Thanks in advance! — Quantum Eleven 14:09, 15 June 2006 (UTC)
Hello,
I am studying tensor products and I think it would really be useful to think about this problem in general
let M be a right R module, and N a left R module
Now let us assume nothing about the ring (commutativity, division ring,...)
now consider and an element in it of form
Now when is
I know just saying "one of them must be zero at least" is simply not true, at least when I am working with non-divisionrings... But then what is the criterion?
Could this be it : one of them must be "divisible" by an element in the ring R such that the other one, multiplied with it, gives zero?
Thanks,
Evilbu
14:16, 15 June 2006 (UTC)
Thanks. So what do you think? This criterion is not correct? I stress again that the ring (apart from having unity) can be as free as it pleases in all it weirdness, and so can the modules. Nobody seems to be comfortable answering this question. I studied constructing tensor products (with balanced products and all) , which eventually implied taking a quotient (which is a result of the relations) of a free abelian group. So an element in the big free abelian group gives zero in the quotient if it is a finite sum of several elements given by those relations ( I am taking of elements like ~. There can really be millions of terms in a sum like that, so I don't see proving a criterion in this way can ever be done?
Anyway, as always, I stress my gratitude for the kind, quick and to the point I help I receive from this wonderful site.
Evilbu
14:25, 16 June 2006 (UTC)
If one holds a piece of string between two points on a sphere, the string would be tracing the arc/curvature/perimeter/circumference——i.e., "great circle"——segment between the two points, which would equal the central angle, . To find the distance between the two points you would multiply the central angle by the sphere's radius, as the radius equals the radius of the circumference. With an ellipsoid, however, the radius of the body and the radius of its circumference is different. You have two principal curvatures, (north-south,east-west), and their corresponding radii,
. Curvature in a given geodetic direction, , is given as
. The corresponding radius of curvature ("in the normal section") is then given as
. But, if you take a minuscule distance (i.e., ≈ 0), then
not ! There was a stub for
arc recently created. Would the second equation, equaling , be the "radius of arc", thus the equation of arc would be ?
If you divide any north-south distance by it equals the average value of M within that segment, and a minuscule east-west distance (since, except along the equator, east-west along a geodesic only exists at a single point——the transverse equator) equals N. So what is a minuscule distance, in a given geodetic direction, divided by , a radius of? Curvature? Arc? Perimeter? If I Google "arc" or "radius of arc" (or even "degree of arc"), all I find are simplistic spherical contexts, nothing elliptical, involving M and N! P=(
I understand basic, concrete geodetic theory (besides ellipticity, there is curvature shift towards the pole as the geodetic line grows, culminating in a complete shift to north-south for an antipodal distance, since north-south is the shortest path), so I know you can't simply take the spherical delineation, average all of the radii of curvature/arc along the segment and multiply it by to get the true geodetic distance (though, the difference does seem directly proportional to the polar shift involved——i.e., the smaller the distance, the closer this "parageodetic" distance is to the true geodetic one!). But I digress... P=)
~Kaimbridge~
17:20, 15 June 2006 (UTC)
I am currently making a program to generate a random name using United States Census data and Markov chains. However, I want to have a little more flexibility in the process. So I want to be able to make a bridge between a given beginning, some given middle letters, and a given ending, so I can generate a name like Mil???r?a. Currently, I am using a three-letter window. Does anyone know how to generate this bridge? -- Zemyla t 21:35, 15 June 2006 (UTC)
There is a certain word puzzle, that I have heard many times before. I have searched for said puzzle, but cannot seem to find it anywhere. I was wondering how the math works out this way in this puzzle:
Three men go to a motel and rent a room. The deskman charges them $30 for the room. The manager of the motel comes in and says that the deskman has charged them too much, that it should only be $25.
The manager then goes to the cash drawer and gets five $1.00 bills, and has the bellboy take the money back to the three men. On his way up to the room, the bellboy decides to give each of the men only one dollar apiece back and keep the other two dollars for himself.
Now that each one of the men has received one dollar back this means that they only paid $9.00 apiece for the room. So three times the $9.00 is 27.00 plus the $2.00 the bellboy kept comes to $29. Where is the other dollar?
Why does it come out to $29 and not $30? I always suspected that it was because you cant multiply the remaining money the men had to get the right amount, but I'm not sure... Just curious.
I've been learning over the years, when I find myself in disagreement with nearly all experienced mathematicians in existence, to start with the assumption that I'm completely, shamefully, blasphemously wrong, no matter how it looks to me, and go from there. Because it pisses people off less, and because it's usually true. So, tell me how I'm wrong.
I don't get one-to-one correspondence as a way to measure infinite numbers. I understand(the nonrigorous version) how it works, and I can see how it's a natural extension of normal counting, but it's not how I think, and it's not how I've ever seen infinite numbers. Take the alleged one-to-one correspondence of, for instance, natural numbers and their subset, even numbers. That doesn't make sense to me. Even numbers are sections of an extent. It doesn't make sense to rip them off the number line, jam them together like the vertebrae of a crash victim, and shove them back on, while not doing anything of the sort to the numbers they're being compared to. Here's how I'd compare them, and here's where I need correction. They are each prespecified, patterned, easily identifiable sections of an extent of number line. It is guaranteed that no natural number can exist that is more than one away from an even number, and no even number exists that is not a natural number. They are already, inherently and inextricably, in a particular correspondence with each other. So, take a number x. x can be anything we want, a positive number of some amount. Now, count the number of whole numbers up to (and including, if possible) x, and the number of even numbers up to and including x. Keep doing this as x grows, and let x pass each and every natural number in turn. How many natural numbers will there be as it grows? floor(x). How many even numbers? floor(x/2). What, then, is the ratio of whole numbers to even numbers? 2:1, not 1:1 I'm think the rules of limits back me up on this. This is just a long (and hopefully clear) way of saying what seems so obvious to me: that there are many many whole numbers, and exactly half of them aren't odd.
This last bit is assuming I didn't screw up above. I can understand how the lack of one-to-one correspondence is excellent reason to separate different infinite numbers, but why do people seem to think that the presence of it proves they're exactly the same? Any help is appreciated. Black Carrot 23:34, 15 June 2006 (UTC)
That's a pretty impressive response. I've read them carefully, and I'd like to list the main points, so you can tell me if I've left any out. I'll respond to them as I can.
BTW, please don't toss comments into the middle of my post. These discussions are a lot easier to follow if they stay chronological. I'd like to boil the answers down even further, to the things that seem most important.
Using these responses and the language in them, I'd like to rephrase my original question in a clearer, more concise way: "Is the idea of one-to-one correspondence really the only valid way of showing infinite amounts are different from each other? Doesn't it seem like they could be separated out more than that? How about this way that makes sense to me; it seems just as common-sense as one-to-one correspondence, yet gives an answer that seems more right." As best I can tell from the responses, I was both right and wrong, which I see as a net success. All further comments and corrections are welcome. Black Carrot 19:42, 16 June 2006 (UTC)
That's the kind of talk I like to hear. Thank you, and may the Invisible Pink Unicorn protect you and your family from the ravages of the Purple Oyster (of Doom). Especially, thank you for telling me the name of what I was grasping at (it's amazing how much of math is vocabulary), and for confirming that it's not a completely insane/uneducated/baby-with-blocks-like idea. Black Carrot 02:08, 17 June 2006 (UTC)
This is entirely accurate.
Simplify both sides two different ways.
Divide both sides by (x-x).
Divide both sides by x.
Look what I got. Can anyone explain? Political Mind 01:32, 16 June 2006 (UTC)
Brilliantly simple. So when I am at , it is really ? Ok, thanks! Political Mind 01:37, 16 June 2006 (UTC)
Thank you, will change. Political Mind 01:46, 16 June 2006 (UTC)
In a differential equations textbook I'm working with, there's an exercise where the student is asked to compute the Laplace transform of the function f(t)=t*sin(ωt). Doing it from the definition, by integrating t*sin(ωt)*e^(-st) from 0 to infinity is tedious, but works. The book offers a hint for a simpler method: begin with the fomula L[cos(ωt)]=s/(s2+ω2), and just differentiate both sides with respect to ω. This works out nicely enough, as long as you assume that differentiation w.r.t. ω commutes with the Laplace transform operator, but that seems like a highly unobvious thing. Can someone help me see why it's valid to say that d/dω[L[f(ω,t)]]=L[d/dω[f(ω,t)]]? - GTBacchus( talk) 02:58, 16 June 2006 (UTC)
Can anyone give me a rigurous proof based in the formal definition of limit? Thank you very much ;)
What I would like my GRUB to do is the following:
All this comes from me wanting to use the same partition for the two OS's paging space. Anyone knows if it can be done? Thanks in advance. Cthulhu.mythos 09:46, 16 June 2006 (UTC)
Hi, some time ago I asked this, I have given the link.
I wanted to know, if you had a covariant functor F from the category of R modules to the Ab category, how you could see the left derived functor as a functor, from to Ab
Now there were people proposing I go to derived category but it still doesn't clear things up.
This is my proposal to understand this for myself :
see L_n F as a functor from the category R-modwpr to R-mod
R-modpwr is the category , of which the objects are pairs with M a left R module, and C a positive complex, over M
morphisms between them are morphisms between and , along with a chain morphism \alpha (for which everything commutes) I mean if :
then
So my module does really depend on the chosen complex over the module.
Is this the best approach? Or am I just way off with this. It seems be the only way I can understand it.
Evilbu 17:30, 16 June 2006 (UTC)
Please. I couldn't find one.
What is the smallest simply connected polyomino that cannot be tiled to fill the plane using translation, reflections and rotations? -- SGBailey 23:18, 16 June 2006 (UTC)
Yo,
So it seems that since MD4, MD5, SHA, SHA1 etc are all "broken", with a recommendation not to use in new infrastructure implementations, they must not have been "proven" in the first place. What I mean is that there was a day when MD5, for example, was thought secure, let's say in 1995, and this meant that some smug researcher could say: "You know, if every computer at this university were networked and at my disposal, there still wouldn't exist a set of instructions I could fill their memory with such that if left plugged in for 72 months, the array would be guaranteed to churn out two distinct files with the same MD5 checksum by the end of that time. Maybe within 100+ years, but not in 72 months." (The 100+ years is meant to allude to brute-forcing without reducing the bitspace, whereas the 72 months alludes to the fact that MD5 is in fact "broken" and does not require a full brute forcing).
So, in fact, this researcher would have been wrong, because even without newer technology (using his 1995 university equipment), we can now construct a set of instructions (program) that, were he to run it on all the computers at his university, would produce the collision in 72 months instead of 100+ years. So what I mean is that a mathematical proof must not have existed in the first place that no such program could exist.
So, now, I am asking, is there any hash function today that isn't just wild conjecture, but actually PROVEN not to reduce to fewer than x instructions on, say, an i386 instruction set to break?
As far as I understand it: does any hash have a mathematical proof that no program exists (the turing computer cannot be programmed to) to produce collisions in fewer than 2^x operations, where x is guaranteed to be at least a certain number?
I understand that quantum computing can "break" cryptography, but only in the sense of using a different physics. No program will make the computer in front of me turn into a quantum computer, but surely there is a hash for which there is a proof that no program exists that will turn the computer in front of me into a speedy collision-producer ???? —The preceding unsigned comment was added by 82.131.188.130 ( talk • contribs) .
If you proved that finding collisions for a given hash function could not be done in polynomial time, that would prove P!=NP What about proving that, although the time is polynomial, the factors mean that a theoretically optimal program on i386 architecture with unlimited RAM (as for an arbitrarily large cluster) could not produce an answer on average in fewer than 10^x operations, where the number of zeros (x) puts it out of the reach, at least, of THIS computer over the course of 24 hours???
Okay, I just realized that what you think I want is a proof that finding collisions will take more than polynomial time (for example, exponential time). However, I don't need this. It doesn't matter if a collision can be found in exponential time. It doesn't even matter to me if a collision can be found in CONSTANT time, as long as it guarantees that the constant value translates to more than x operations. I don't care how it scales theoretically, I care about the actual proven minimum. I don't want to hear "Hahaha, just kidding. Tricked you good we did, us mathematicians, because now you can crack [find a collision for] SHAxxx on a rusty laptop from 1987 in 35 minutes." That's essentially what happened to MD5 (read that article, and SHA). Now I want something that that won't happen to. At least, not on a normal computer.
Thanks for everyone's input! I'm putting the short answer in the section below. The only question I still have is whether RandomP's original answer referred to just putting in "precooked answers" into the laboratory computers, and therefore "getting" them instantly. Of course, I referred to getting them algorithmically, rather than just coming back from time with precooked example answers. (Of which of course there are guaranteed to be many, as RandomP seemed to correctly point out). I wonder how to phrase this issue more rigorously, so that "coming back with precooked answers" is ruled out.... I'll ask this in a new question below. 82.131.190.200 18:45, 20 June 2006 (UTC) excde
The short answer is "No, no (non-trivial) bounds have been proved for any hash function."
OK, I've been have trouble watching some videos on Mozilla Firefox... I've tried downloading all the plugins on this page ( https://pfs.mozilla.org/plugins/?action=missingplugins&mimetype=application/x-mplayer2&appID={ec8030f7-c20a-464f-9b0e-13a3a9e97384}&appVersion=2006050817&clientOS=Windows%20NT%205.1&chromeLocale=en-US).
And it still won't work and it won't give me a plugin recommendation.
This is what I get when the video won't work... http://www.esnips.com/doc/2968f507-91c0-4e20-b991-8bb90e9fd09a/Mozilla-Friefox-Problems.jpg
Thanks! ~Cathy T.~
It does this on my mom's pc too... ~Cathy T.~
Yeah, that's what I've been doing... using internet explorer. Going to check out that extension. Thanks! ~Cathy T.~
Thanks... I just downloaded the extension and it works! Thank you so much! :) ~Cathy T.~
Yeah, it's updated. ~Cathy T.~
Hi,
I have been studying homological algebra and I have seen several important theorems, but I still haven't found any theorem (in my syllabus or on the web) that is called 'The fundamental theorem of homological algebra'.
Is there one? (because if there is I would feel a little silly studying all this and still not knowing what it is..:))
If so , my guess would be that it is the theorem about connecting morphisms, that allows you to create a long exact sequence of homolog y modules from a short exact sequence of chain morphisms?
Or is this the one, but in a much more general abelian category?
Thanks,
Evilbu 08:42, 17 June 2006 (UTC)
Hmm, but once I read an article, I think here on Wikipedia, about math in popular culture, and I think it said something about a movie in which a professor 'demonstrates the fundamental theorem of homological algebra for an obnoxious student'.
It is a shame I can't find it back.
But you think there isn't one? If I had to force you to pick one which would it be?
Thanks,
Evilbu 11:12, 17 June 2006 (UTC)
Thanks. And it was also crucial in Mayer Vietoris in topology hmmm. But I mean wouldn't the most general case, involve abelian categories. But I was wondering, how would you go about categorically defining quotients (for homology modules?)
Evilbu 16:06, 17 June 2006 (UTC)
The "movie in which a professor 'demonstrates the fundamental theorem of homological algebra for an obnoxious student'" is probably a film called It's My Turn (look it up on imdb, I haven't seen it though I'd love to find a copy...) in which someone proves the Snake Lemma on a blackboard. This isn't really a good candidate for the "fundamental theorem of hom. alg." though. It's My Turn gets referenced in Weibel's book An Intro to Hom. Alg. -- 86.15.136.29 22:58, 24 June 2006 (UTC)
Hello. May somebody tell me how to find the limit of the following sequence?
lim 1/n * ( (n+1)(n+2)...(n+n) )^1/n
n->infinity
Thank you very much for your patience.
Is there a compact integration of the formula sin(x)/x? Black Carrot 21:03, 17 June 2006 (UTC)
Hi. If possible could someone please confirm the following relationship between function and the derivative I've found. I'm getting some answers right and some wrong with this equation, so I'm not sure if the textbook is wrong or I have a equation that works some times and not others.
Thanks, -- DanielBC 22:46, 17 June 2006 (UTC)
If anyone here has a copy of Stalking the Riemann Hypothesis: the quest to find the hidden law of prime numbers, I need some help. He explains things very clearly for about the first third of the book, then starts leaving out more and more details. On pages 85-90,
The Plasma TV manufacturer Panasonic produces widescreen plasma TV model X. If they price it at $20000 then they can sell 50 units per week. If they half the price to $10000 then they can sell 500 units per week. If they half the price again to $5000 , they can sell 5000 units per week. And finally at a price of $2500 they can sell 50000 units per week.
The actual selling price for the widescreen plasma TV model X is $2800 dollars. What is the actual cost of the TV.
I have calculated that the volume sold is
Vol = 5 * 10 ** ( 1 + (log(20000/price)/log(2)) )
or
The total profit is
Which we can plot as a X,Y graph
Setting the Cost to $1000 , produces a graph with the maximum y at x= 1426
Refer to this graph.
My question is this. Apart from changing the value of Cost and reploting the graph. How else can I find the value of Cost which correspond to a graph with the maximum value of y(Total Profit) at the point of x=2800 (Price = $2800).
Ohanian 02:41, 18 June 2006 (UTC)
Your derivative is wrong. It produces the cost of 2189 instead of 1960.
211.28.122.175
09:56, 18 June 2006 (UTC)
So I need to find the derivative of this
211.28.122.175 10:02, 18 June 2006 (UTC)
Not essentially different, but a bit less strainful in some respects.
Start by rewriting the expression for the profit in the form:
in which C is the cost. For the purpose of finding a maximum, the value of a is irrelevant, but λ = (log 10)/(log 2) ≅ 3.3219. Taking the derivative with respect to x yields:
which is zero for:
or, plugging in the numeric value for λ,
The value 0.6990 is 1 – 0.3010, where 0.3010 is the base-ten log of 2. -- Lambiam Talk 13:12, 18 June 2006 (UTC)
I've seen a symbol that looks like an integral symbol with an "o" in the middle of it. What is that symbol? -- Shanedidona 03:27, 18 June 2006 (UTC)
Actually i want to make a story and wanted to know how to make a simple virus.
Hi, i am having problems understanding the differences between the secant method and the method of false position. I have an exam tomorrow so any help would be appreciated. The formulas look pretty much the same and they seem to do the same thing so what's going on?
chemaddict 13:20, 18 June 2006 (UTC)
Hi
If I'm too dense to understand the Ring theory article, even by using the internal links to explain the explanatory terminology (words like "and" were OK... most of the others were beyond me) is there any way I'll ever understand what the heck Ring Theory is?
You may have gathered that I'm no mathematician... but I have a friend who is. He specialises in Ring Theory. And he is utterly incapable of explaining it.
Based on those tips, let me try to give an idiots' definition: Simply put, a ring is a place where the "normal" rules of addition and multiplication work. Is that it? -- Dweller 15:25, 19 June 2006 (UTC)
"Yes" I understood. Everything below it was wasted on me. I particularly enjoyed learning that "for every number a there is also a number -a." The whole thing seems inherently contradictory. What would be a workable idiots' definition? -- Dweller 16:33, 19 June 2006 (UTC)
If you are "too dense" to understand a given article, see if there is a simple english version of it. Russian F 23:39, 19 June 2006 (UTC)
Here the problem -
There are two computers,their respective LANs they connect to the internet via their respective proxy servers
Computer A -- Proxy server1 <Internet> Proxy Server2 ---- Computer B
Now is it possible for computer A to computer B and transfer data ?
It is possible for them to transfer data using a common server on the internet,which is whati think yahoo messenger and google talk does to transfer text from one computer to another. They both can connect to a single server and transfer data but if they have to transfer large files it will eat up the bandwidth on the server.
I managed to figure a technique called 'NAT Traversal', but I think it is limited to cases where computers connect to internet using NAT and not proxy servers.
musing: I am behind a proxy server and BitTorrent clients like the official client, Bit Tornado etc dont let me download even a single byte,at the most they have an option stating they can 'proxy the communication to the tracker using the proxy' which I think is extremely trivial. But with clients like Bitcomet, they can proxy even my data, so I can seamlessly download anything,with great speeds. (I downloaded FC5 at speeds around 70-100 KBps which is great on my connection)
This indicated it is possible to achieve this, but how ?? —The preceding unsigned comment was added by 203.145.128.6 ( talk • contribs) .
I have a blog and want it to display a fake blog-page for a certain IP address. That way a certain computer won't be able to see what's really on my blog. I would like to know how I can do this.
Goedel's completeness theorem, if I am not mistaken, proves that any logicall consistent statement can be proven in 1st order logic. Goedel's incompleteness theorem, if I am not mistaken, proves that there exist mathematical truths unprovable by any set of axioms in 1st order logic. But surely a mathematical truth is also logically consistent and can be proven using 1st order logic? How are these 2 theorems reconciled?
I have a polynomial of the form:
and have a few questions.
Thanks for any help.
x42bn6 Talk 01:43, 20 June 2006 (UTC)
I badly want to understand monstrous moonshine. I'm very good at math and I already know the basics of group theory and complex analysis, but it's still tantalizing gibberish to me. Here's the bulletin for the math department of the university I attend: undergraduate and graduate. What courses should I take in order to understand monstrous moonshine? — Keenan Pepper 04:53, 20 June 2006 (UTC)
changes in agriculture in the world till today
I would like to state requirements for a proof in terms such as "This architecture (i386) cannot produce collisions in fewer than approximately 100 billion operations" on average (as a simple bounds), so, for example, 100 seconds for a 1 GHz cpu, or less time if you use higher speed or multiple cores/nodes. I'd like to phrase this like this: "Here is an idealized computer, it's a Pentium 4 with 1 core running at 2^32 hertz and accessing 2^32 bytes RAM" (I guess to idealize further we could assume the full ram is full-speed cache, assuming zero latency and more bandwidth than the CPU can consume in a cycle). "Does there exist any digest algorithm (hash) that is proven not to be 'breakable' in fewer than 1,000,000 such processor-hours for a certain length? ( This question was answered above, and the answer seems to be "no"). However, the issue is that in fact the answer as I asked the question is literally "yes" since you can get two files with the same checksum/md5 sum etc in 0.1 seconds, if you just bring back the files from the "possible" (since the pigeonhole principle guarantees they exist.) Of course, for short files (like 4-byte files) you can just brute-force it on the spot. So I want to rule this out (brute-forcing based on the small file length) and also rule out bringing in homecooked files. How do I rigorously phrase my algorithmic requirements?
My friend found that in two dimensions, there can only be two lines that form a perpendicular at one point. In three dimensions, there can be a maximum of three lines intersecting and forming perpendiculars with each other. So he said that by continuing the pattern: In four dimensions, there can be four perpendiculars, with time as the fourth dimension. I understand what he's saying but I don't agree. Is this true or not? -- Yanwen 20:15, 20 June 2006 (UTC)
(stolen from Martin Gardner) A square has two diagonals, which intersect at right angles. This corresponds to the fact that a square is two-dimensional. A cube has four spatial diagonals (each of the eight corners is joined to its opposite corner) which intersect at right angles. Hence a cube is four-dimensional :). (Exercise: find the fallacy in this argument.) — Blotwell 02:53, 21 June 2006 (UTC)
Just to make this more fun, lets change the question a bit:
In all cases, the given flats are "in general position".
Answer: 2,5,14,42. The last is of course the answer to the universal question. The questions and answers exemplify Schubert calculus, by the way.--- CH 22:31, 21 June 2006 (UTC)
is there a quick way to make a formula that tracks and record visitors to a website and compares them to other websites?-- Bee( y) T i 01:32, 21 June 2006 (UTC)
I am sure there is a quick way to make such a function. previous_hits + 1 = current_hits It is called a hit counter. However, if you want something specific, the particular programming language you plan to use would be required to formulate the function. -- Freebytes
We know that to find the co-efficient of the principal part in the expansion of a complex function f(z),we can use the residue theorem.BUT z=x+iy, so y=0 gives f(x).So can we use this residue theorem to find the co-efficients of any function in case we need to partialty fraction them?
Just in case, Residue of root a of order m R(a,m)=(1/(m-1)!)*lt[z tends to a]{(d/dz)^m-1 (z-a)f(z)}
Hi, Can anyone tell me which is the most complicated or longest equation ? I know that complicated equations need not to be longest.But just curious as which could be the longest equation existing.
What I am asking is any textbook mathematical or physical equation. A very simple example would be E = m×c2 .
The Lagrangian (and therefore also the equations of motion) for the standard model are so long in most notations that they can't fit on a single page. - lethe talk + 11:31, 21 June 2006 (UTC)
In celestial mechanics, the literal expansion of the disturbing function in terms of orbital elements is an ugly beast, even to low order in the eccentricities and inclinations. In other news, how do we not have an article on that? Melchoir 19:31, 21 June 2006 (UTC)
Could you please help me with the following table for macroeconomics, I understand which each column represents but am having trouble with the math. If someone could complete the first row I should be able to figure out from there. I know I, G, and X are constant. Does AE have to equal Y? Thanks
Y C S I G X M AE 100 200 300 400 500 600
Given the following:
C = 50 + 0.75Y M = 40 + 0.15Y I = 30 G = 20 X = 100
Y C S I G X M AE 100 125 30 20 100 55
You will get a bit further by noting the basic macroeconomic identity:
Y = C + I + G + X - M
AE stands for Aggregate Expenditure and is defined as
AE = C + I + G
Savings S is defined as what is left over after subtracting consumption C from disposable income (Income less Taxes):
S = Y - T - C
You do not have an expression for Taxes, so it does not seem you will not be able to fill out the S column. In a problem like this Taxes might typically be described by an equation such as T = t*Y where t is a tax rate.
Vickrey 18:42, 24 June 2006 (UTC)
Did anyone have any luck on my macroeconomics question?
Has any name been given to the numbers x^2 + x (x integer)? I am interested in them because (x + .5)^2 = x^2 + x + .25, and these "half-integer squares" can also be used in Fermat's factorization method a^2 - b^2 = N to produce factors (a-b) and (a+b) of even numbers; as you can see (a-b) and (a+b) are still integers, with both a and b half-integers. -- Walt 15:42, 21 June 2006 (UTC)
Thanks guys. Any opinions on the appropriateness of cross-referencing the article to/from perfect square? Or is the relationship only obvious from the problem I'm working on? -- Walt 12:42, 22 June 2006 (UTC)
how do i solve this? 88.153.89.18 09:52, 22 June 2006 (UTC)
Yet Another Linux Question... :)
I will soon take the plunge into Linux, and am planning to set up a dual boot Ubuntu / Windows XP system for the time being, so I can experiment with both OSs, and hopefully use the advantages of each as best I can. I have some Linux experience (from working with it at the lab), but not a huge amount.
My question: what do you recommend as filesystems? I have been trawling through the Wikipedia articles on the various filesystems to see what filesystem is compatible with which OS. I am trying to achieve a compromise between performance and compatibility, and will obviously need at least two different ones...
FAT is readable and writeable by both Windows and Linux, however, I detest it with a passion (I have long since stopped counting the number of defrags I've had to do on it), plus, the filesize and volume size limitations will probably come back to bite me. I would prefer to avoid it if I can.
How good is read / write support for NTFS in Linux? (the external links at the bottom of the article point to several projects, but I must admit my techie knowledge is insufficient to judge them).
Conversely, it seems that ext2/ ext3 read/write support seems to exist under Windows (again, information gleaned from the articles) - does anyone have any experience with this?
And, to close, a somewhat more basic question - in your experience, how much do you find yourself needing read/write access between your different OS's partitions on a multiboot system? Do you have any advice for me in this regard? Thanks muchly in advance! — Quantum Eleven 12:23, 22 June 2006 (UTC)
Hello, How do we easily find a biclique in a bigraph, after applying bigraph crossing minimization heuristics (like by barycenter) to reorder the two vertex sets of the bigraph. This paper "SPHier: Scalable Parallel Biclustering Using Hierarchical Bigraph Crossing Minimization" suggests that we use Breadth First Search after this reordering procedure, but I'm not sure how exactly this is achieved. In their example Figure 1(C), supposing we started on node Y, BFS (ignoring loops) will wield nodes A, B, W, X, C, D, Z. I'm not entirely sure how we extract the bicliques {A,B} + {Y,W} and {B,C} + {W,X}. I'm sure the answer must be pretty obvious, but I'm missing something here.
Many Thanks ! -- 213.22.236.27 20:55, 22 June 2006 (UTC)
Hi folks; I am writing a dissertation on the nature of Time. Why ? Because we know nothing about it.
I have written about the human perceptions of Time, and have compiled 7 axioms. I now need the assistance of a mathematician to create and formulate the maths.
So this is more of an open request for assistance than a question. I live in BC, Canada.
Kind regards, Bruce >>>>>
Yes I have read all of those references (and their sources), many times. Interestingly, Albert said very little about Time itself, other than to clearly define the (human) ways of measuring simultaneity and the consequences arising therefrom, across distances and with relative speeds of observers. But, Time is not measured by humans. Our clocks simply emulate time with great precision. Our science knows nothing about it. We need to sit back and think again. Cheers, Bruce >>>>>
Yes, I am concerned about the physics of Time; the philosophy will take care of itself as we develop the mathematics. OK, I don't know whether it will be as simple as F=ma or it will be vastly more complex. Currently, I believe that there is some linkage with String Theory. Time-lines connect everything that we can perceive. Cheers, Bruce --email removed-- >>>>>
>>>>> I am now a "logged in " user with moniquer "Time'sup". I am willing to post the draft dissertation as suggested by Igny. Perhaps you folks can point me in the right direction. Cheers, Bruce >>>>>
Kind regards, Bruce bnb at ahausa.com Time'sup 01:34, 26 June 2006 (UTC)
Cheers, Bruce Time'sup 18:07, 26 June 2006 (UTC)
I'm looking for a way to divide one multiple-precision integer by another. One of the things I was looking at was using a number-theoretic transform, but I can't figure out how to get the remainder separate from the quotient. Plus, it blows up if one of the coefficients in the number-theoretic transform of the quotient has a 0 in it. Can someone help? -- Zemyla t 17:11, 23 June 2006 (UTC)
I've done my basic google searching, but my only finds were way over my head. I currently have a SanDisk Cruzer Mini with 1.0 GB, and I'm interested in making it bootable.
I understand how to switch the order in BIOS, but I think there are some needed components to go on my stick, something about bootsectors?
I would be interested in doing this on a computer with XP, if that matters. -- 134.134.136.4 22:52, 23 June 2006 (UTC)
Just a few things: I don't have a floppy drive, didn't think I'd ever have use for floppies again. Also, I'm afraid to format something like a C drive without some sort of confirmation that it is the correct C drive. I'm not going and formatting my only system drive here, right? It's a lot easier and safer for me to format the drive from the Windows GUI with a simple right click. =P. Any Suggestions? -- 134.134.136.4 20:41, 27 June 2006 (UTC)
There is a math code at http://inthemath.com and I have 2 questions 1.)Is it a math code? 2.)Did I make it up? —Preceding unsigned comment added by Lightprize ( talk • contribs) 22:23, June 23, 2006
That's allot. First, whether I did it or not is a waste. If I didn't the law will handle it.
I asked if it fit the description of a code, not whether or not "YOU" thought it was valid-you ain't seen the rest. But are you saying that if it were more complex it would be okay? I think that some say it can't be anything "because" it is too simple.
And I guess you are saying that I did find it, and that I did't make it up? Whether it is valid in your eyes or not.
So did find a code, didn't I?
Predictable? 12 and 3 were predicted. At least that is what I was looking for. And I would not have been able to find them if they were not there.
I have the advantage of having seen more of it than you have. From that, I say it has meaning, and I have provided more than enough. I didn't say it would repair the ozone layer, or bring home those MIAs from Vietnam. So don't expect everything. But can you imagine "if" it were a message, being ignored because the receiver didn't like how it was written?
"If." You see I am not married to the thing. But I am giving it the benefit of the doubt. Nothing I have heard has shown me why I shouldn't. I will keep looking till then, while I try and deliver what it does say.
Those 3 words that you are talking about are 1,5 and 6 and they add up to 12, that makes them part of the original code.
But do you see where you have gone? I had to look up numerology after it kept popping up in your writings.
The code I am talking about says nothing about "magic" numbers" or predicting the future, or getting insight into anyones personality.
You are trying to make it harder then it is, I said I found a math code, I did. The patterns are there, "in math." The number was 12 "what if I reversed it" you say? Why would I want to do that? I don't know anything about the meanings of numbers, other than what they add up to.
Look back at the way you sound, and the way I sound, which one of us is talking about numberology? You are trying to feed that to me, but you have seen the numbers and they are "invincible in their simplicity," why make them hard? Talk about what is there, not what you imagine should be there.
That maybe the simpliest explanation, but it is not the most interesting. What if I thought it wasn't what it seems, and it was? I have to take it at face value, and then be proved wrong. The references I "added" were metaphors, and they sound mean because people were being mean to me. I asked a question about what I found and I got something else. I believe in a designer with evolution as the design-no more.
I looked at Ramsey Theory, and a couple of other theorms, and it occurred to me that science is addicted to complex math. And while I have no doubt about the success of scientific thinking, few outside science can understand it. I know I don't. Science is looking for a formula in math to "unite the forces" so they are looking for a message/code in math, and "know" it is there. How did it get there? And if there was a message/code meant for the "masses",(however it got there)would it be left to science to interpret? Or would it be easy enough for all to understand it? Like the simple, consistent patterns at my site? —The preceding unsigned comment was added by Lightprize ( talk • contribs) .
The question was: since science "knows" that the unity formula is there in math (and I believe them)how did it get there?
Oh wait, I'm sorry. The mathematics behind the four of them would match up into some type of an equation, whatever it was. I was not trying to be funny.
I understand what you are saying, but it seems here that not only is science addicted to complex math, but it also has to communicate in the most complex language it can. A simpler way to say what you did would be that because the forces are united in nature, their math must come together in a math equation of some kind, once the method is found. I was looking for a simple code in math, since everything else was done. I found some patterns, and then some more. I thought they could not be anything, so I checked out the names in other languages, and nothing. So the code was unique. People have looked at where the numbers came from and dismissed them saying they can't mean anything. Where would science be if researchers listened to what people "thought" about what they were doing, without "proving" what they said?
Are the names of the numbers in English arbitrary or fact?
So, the names in English are a fact than.
I don't see where I had allot of trouble, but it took allot of time for those there to say I found the patterns I did. And I thought it was a simple question. Whether or not anyone "thought" the numbers meant anything. Only I (right now) see where those numbers go. And time will tell.
Accuracy, should also be sought in conversation. At which time did I apply the arrangements of letters to quantum physics? Stick to what the numbers say instead of what you "imagine" them to say.
Would you say that there is a certain "brevity and elegance" to the code at inthemath.com? Brevity and elegance is what helped me to see them for what they are.
How long did it take you to get thru the site? Quick, right? That is brevity. All those symbols and numbers did what they did without fuss, and without anything being left out, or left over, thats' elegance. The code will soon show a connection to the theory for everything, but not by counting the letters. Time will tell, and not allot of time either. Accuracy, again. I asked what science was looking for in a message, and patterns and symbols, in math, is what they are looking for. [Lightprize.]
I know this is not the right place for this but, you know how children take on the characteristics of their parents? Well where did the characteristics of life come from? Electromagnetic radiation is 2 energies blended into 1. The characteristics of its electrical part are negative and positive, and those of its magnetic part are attraction and repulsion. That's No, Yes, I like you(love) & I don't like you(hate). That is the mental/emotional nature of life, and math to boot. Because negative is subtraction positive is addition, attraction is multipulcation and repulsion is division. Now this does not have to be right, but it is the best description of the soul of life that I have ever heard. And light is 1 force, made up of 2 parts. Sometimes some interesting things can come from something seemingly of no value. [Lightprize]
Everyone, from that I have seen from the responses, is saying that the issue with your 'discovery' is that it only applies to English, and that numerology consists of people that have found more fantastic 'discoveries' than you. English was not created. Here is an example of a constructed language: http://sipen.com/projects/language/ Notice the differences from a logical viewpoint? Words created in an ad hoc manner are done so in languages that are made by numerous people in most circumstances. If I were to change the name of the word "two" to "cianide" in your language, would your code still work? All it would take to do that is for someone to repeatedly use the word until others began using it. (An example of this is using the word "cool" to mean awe-inspiring or "bootylicious" to mean voluptuous.) -- Freebytes
I recently took a practice SAT test from The Princeton Review and I didn't do very good on the math section. The following are the ones I didn't know how to do.
I would really appreciate any help. Thanks. schyler 01:44, 25 June 2006 (UTC)
I am actually no about to attend college. I am just now going to be a sophomore. The course is specifically designed to have you see what to look for when you are learning the stuff in class, so some of it, I haven't even learned how to do yet. Thank you for yall's help though. schyler 14:12, 25 June 2006 (UTC)
(I do hope this question will not be too lengthy..) I am a 3D animator, so although I am fairly profecient wiht it, math is not my strongsuit. But because I don't feel like spending thousands of dollars buying one, I have decided to code a highly simplified fluid dynamics solver for special effects in my animations.
Note that unlike CFD/engineering applications, my purpose is NOT to achieve complete accuracy, but to create a convincing image.
In my program, the Navier-Stokes Equations are solved on a 3D grid. The velocity and density of the fluid are sampled at the center of each grid cell. I do not fully understand the Wikipedia page explanation of the NSEs, however, I do have a vague understanding of the form Jos Stam presents them in a paper he wrote:
This involves two 3D grids: a vector field that stores the velocity of the fluid, and a scalar field that stores the density of the fluid.
in the first equation: u is a vector representing the velocity of the fluid at a given point, t is a timestep by which the simulation advances each frame, ν is viscosity, and f accounts for the addition of forces by the user.
in the second equation: ρ represents the density of the fluid at a given point, t us a timestep by which the simulation advances each frame, κ is the rate of diffusion, and S accounds for the addition of density by the user.
What I am currently concerned with is the term,
which simply states that the density diffuses over time. To implement this in the 3D grid structure I am using, it seems simple: we exchange the density with the six immediate neighbors of the cell we are trying to solve for. However, if the density in that cell must diffuse beyond its immediate neighbors, this is not accounted for, and the simulation "blows up." The only soltion is a shorter ∂t, a smaller κ, or a finer grid with smaller cells. In any case, the effect of diffusion is either lost, or the simulation takes much longer.
Stam wrote a solution for this which is quite elegant--he uses Gauss-Seidel Relaxtion to solve for the new value. It is stable and will not blow up. It is also patented, so I cannot use it.
Given that I am striving for visual appearance and not accuracy, it occurred to me that the effects of diffusion look strikingly similar to the Gaussian Blur filter in many graphics/image manipulation programs. It seems logical that a fast 3D gaussian blur would do the trick for me and work at any time step.
So I look it up on Wikipedia. Apparently, to get a convulsion kernel with Gaussian distribution in 2 dimensions, you use:
Let me be frank--I am only attempting this project because of the simplicity Stam's paper provided. I do not know a whole lot about higher math, so bear with me if this seems like it should be obvious.
My question is: What would this Gaussian distribution function look like in 3D? My guess would be:
is this anything close to correct??
Jos Stam's website is http://www.dgp.toronto.edu/~stam/reality/index.html. The article I am basing my program on is the publications link, it is entitled, "Real-Time Fluid Dynamics for Games."
Although I suppose I could use Stam's code for personal use, I may distribute the code to some friends, and I do not want to risk anything, since I have no attorney... So I am fairly dead set on staying away from the patented section of the code.
Any help would be much appreciated --
Loki7488
09:15, 25 June 2006 (UTC)
I have the slideshow in PDF form, it expands on the paper I am currently reading from and I'm sure I will refer to in as I progress. I have also read many papers written by Ron Fedkiw, Nick Foster, and Dimitri Metexas. I am fully aware of the challenges fluid dynamics presents, and that professional outfits have huge physics teams who get paid top dollar to do this stuff to the extreme... on the flipside, I am also aware of numerous individuals or groups of individuals who have developed very simple fluid solvers. Thanks everyone for the helpful replies! -- Loki7488 14:39, 25 June 2006 (UTC)
The Half-life computation article has undergone substantial revision which has hopefully addressed everyone's concerns. If you have any further comments after looking at the article again, please list the items you do not like, make whatever comment you have and please be specific and allow time for further revision. If there is any reason I can not comply with your wishes then I will let you know the reason why. ... IMHO ( Talk) 12:20, 25 June 2006 (UTC)
Hello,
my sister, who studies informatics and has exams just like me, asked me if I recognized this symbol :
an equality sign with a dot above it
\doteq in latex, but it doesn't seem to get rendered here.
I had seen and stuff like that, but never that.
It appeared as a sign between two membership functions in fuzzy logic (the syllabus is about artificial intelligence).
Can you help me?
Evilbu 16:45, 25 June 2006 (UTC)
How many feet are in heaven? -- 63.170.208.190 17:55, 25 June 2006 (UTC)
I've been grappling with this concept for a while. Now, while I realizes calculus states that .999... theoretically equals one since it's infinitely close, it also states that it will never equal one, since there will always be an infinitely small gap between the numbers. However, consider this equation:
Since it's been established that x=0.999:
Therefore,
I know that practically, this is impossible, since adding no amount of decimals will ever cause 0.999... to actually reach one. How, then, does this equation work? If this problem's already been posted, please accept my apologies in advance. -- Thetoastman 07:11, 26 June 2006 (UTC)
your problem is that you don't picture infinitely many 9's, you just picture them repeating. They don't "repeat" one after the other (this repeating is the process you're imaginging), mechanically or something, taking a bit of time to add the next one: just imagine them all there all at once. Imagine a make a computer game where you live in a town, and in one direction train tracks go off forever, since I don't program them. You can't follow them, because the game doesn't let you leave the town. Now, the tracks are "generally anchored perpendicular to beams (termed sleepers (Commonwealth except Canada) or railroad ties (U.S. and Canada) of timber, concrete, or steel to maintain a consistent distance apart." If you cast a spell "railroad beams to snakes" that turns EVERY railroad beam into a snake, it doesn't matter if you first add a beam where you can still walk to. If instead of "railroad beams to snakes" you just cast "infinite snakes 2 feet apart" and the beams are 2 feet apart, then if you point it parallel to the train tracks, each beam will get a snake. It doesn't matter if you remove the first beam yourself and take a step forward before casting the spell.
Likewise, there are as many positive numbers as negative and positive numbers together, since you can just count them like this: tracks: 1 -1 2 -2 3 -3 4 -4 5 -5 etc. snakes: 1 2 3 4 5 6 7 8 9 10 etc. It doesn't matter.
Likewise, if you start counting at 8 and I start counting at 1, we can count together forever. You won't "run out" 7 numbers before I do.
(This anonymous comment added by 82.131.190.16)
can you please help me to make a bootable disk.-- Saksham Sharma 11:55, 26 June 2006 (UTC)
On windows.-- Saksham Sharma 03:55, 27 June 2006 (UTC)
On windows XP service pack 1
Rotating objects – as wheels on automobiles – appear stopped on TV screens.
What is exact way to calculate probable car speed?
Is it proper to count the “spokes” , assume a wheel diameter, assume a TV frame rate of 60 Hertz, or what?
Please show exact step by step procedure to arrive at an estimate.
I hope this isn’t a stupid question but where will I find this answer if someone responds? -- Itserp 14:52, 26 June 2006 (UTC)
How many mathematicians does it take to change a lightbulb? -- Dweller 20:32, 26 June 2006 (UTC)
That's the spirit! If time is sufficiently curved, perhaps you're still in time to retrospectively beat the scientists. -- Dweller 16:23, 27 June 2006 (UTC)
What is the title of the famous math novel involving shapes of varying dimensions (3d, 2d, 1d) visiting one another and being unable to comprehend anyone of a higher dimension than their own. I believe a rectangle visits a 1-dimensional world to tell them about two dimensions or something. I'm sorry I don't recall much more, but I saw an article on it on Wikipedia several months ago and was thinking about reading it now that I have more time on my hands. - Dave 04:17, 27 June 2006 (UTC)
I am looking to get information on comparing power pc's with Intel processors under the following headings: architecture, cache, speed, power consumption, heat dissipation, future prospects for Intel. If you could give me a few useful links I would appreciate it
show that tan 15+cot 15=4
Is there (Mac) software to allow the remote use of a computer over a fast local network at fast enough speeds to make no visual difference? For example, I want to use a desktop Mac via a (Mac) laptop, but at full refresh, large resolution and 32 bit colour with very little lag. This would be for general real-time use rather than admin purposes. Finally, it would not be X, but a streamed display.
In fact, is this even possible?
I am looking for an online LISP environment to do things in, I would like to be able to save programs as well, can anybody give me a link?
wat is the principle of GESTALT VALUE ? -- 59.161.8.150 15:09, 28 June 2006 (UTC)Roman Nagpur.
this may have to do with something that is 'holistic' and has to be viewed as a hole instead it will not be comprehended. it can also refer to completing an experience...but I don't see how can it be applied to math because it's a psychological concept.-- Cosmic girl 19:51, 10 July 2006 (UTC)
how do we calculate the product of ((r^2)-1)/(r^2), where r = prime numbers starting from 2.
Hello,
I am in need of an automated process (registry file, script, etc.) that I can run on several Windows XP computers that will perform two actions:
1) Add the volume control speaker icon to the taskbar system tray.
and
2) Mute the master volume.
Repeated searches of Wikipedia have yielded no assistance in solving this for me. I've also done some Google searching but have yet to find a solution. Your help would be greatly appreciated!
Thank you.
Hi Guys and Gals! Wikipedia defines percentage as:
"...a way of expressing a proportion, a ratio or a fraction as a whole number,.
what if a percentage is expressed in decimal form? (e.g. 2.45%)
Is there an exact term to call it? Thanks for your help.
In August I'm having a large outdoor gathering, a party of sorts, at my house. I'd like to have iTunes playing music for the roughly 100 guests who will be just outside the house (i.e. not very spread out). What I'm looking for is ways to have good quality sound played outside with equipment that I can use for some other purpose once the gathering is over. Like using it for a stereo set up that I don't yet have or using it for an improvement over the stock speakers on my television or playing music from the computer throughout the house etc.
What I'm working with is a dual 1 Gig G4 tower. If there's a need for wireless, I'm using a Sonnet internal card for wireless internet with a Linksys wireless router. I also have an iPod (and iTrip) which will be able to hold the desired playlist if need be.
What's the best (while not going into thousands of dollars into debt) way to do this? Dismas| (talk) 07:52, 29 June 2006 (UTC)
Hi, I have looked at the optimization, lagrange multiplier and quadratic programming. I have some confusions here. Suppose we are consider optimization in Euclidean space. Since the use of lagrange multiplier can be reduce our problem from constraint to unconstraint ones, and also can be used for all non-linear problem, why do we have to invent some other techniques such as linear/quadratic programming, or some heuristic such as simulated annealing ? -- 131.111.164.110 11:05, 30 June 2006 (UTC)
Thank you for all answers; Then can I just conclude that we have many methods to attack many specific problems, mainly for the reason of efficiency? 131.111.164.226 13:50, 3 July 2006 (UTC)
I was thinking of a pattern in which you start with two numbers, say 1 & 10, and add one to the first number and subtract one from the second number, and take the product of every pair. For example:
1*10=10
2*9=18
3*8=24
4*7=28
and so on.
I decided to graph this, except using a larger range (-10*21 to 21*-10) and a smaller interval (one tenth). The result is the graph you see on the right.
I am guessing this is a parabola, simply by what it looks like, but is there any way to tell if it is one?
Thanks for any help.
-- Tuvwxyz 21:53, 30 June 2006 (UTC)