could u please list out about thirty-fourty applications of infinite series-- 61.1.252.99
{ 10 [3(squared) + 2/4 - 5/8 ] - 9 }
I just want to know if i got the anwser right, because I was bored and I made it up... also, I don't know how to write the squared symbol, sorry. :| . -- Cosmic girl 15:33, 1 April 2006 (UTC)
Cool! I got it right! lol...(I'd be really stupid if I didn't though). thank you Keenan, and Kieff. XD. -- Cosmic girl 16:00, 1 April 2006 (UTC)
An object cools at a rate (in °C/min) equals (1/10) of the difference between its temperature and the surrounding air. If a room is kept at 20 °C and the temperature of the object is 28°C, what is the temperature of the object 5 minutes later?
I think the object's temperature=f(t)=8*exp(k*t) +20, where 8=temperature difference of the object and the surrrounding and 20=the surrounding temperature.
I don't understand where comes into play.
Patchouli 19:47, 1 April 2006 (UTC)
In computational complexity theory, what's the difference between a function problem and a computation problem? Both terms seem to be used fairly similarly. The computation problem article leaves me very confused. -- Creidieki 20:59, 1 April 2006 (UTC)
Hi, this is going to sound insane, but over on Lostpedia, we're working on deciphering the blacklight map on the back of the blast door, as displayed in the most recent episode "Lockdown." There's an equation we'd like to display, but Wikisyntax math markup is making my head spin. Could someone show me how to display the following on a Wikipage? Thank you! jengod 22:37, 2 April 2006 (UTC)
=2rcos[?]
=r*((sqr(5)-1)/2)
-72' = 4rcos"2(72') = r*((sqr(5)-1)/2)
You ROCK!
Thank you. Seriously, you're a star. The original image, enhanced can be found here. I can't make heads or tails of it, but someone broke it down as above. There are also a couple of vector-y equations on the right side of the map. Anyway, THANK YOU.
If you want to join in on the deciphering fun, check out http://lostpedia.com/wiki/Blast_Door. 71.106.0.109 01:01, 3 April 2006 (UTC)
With reference to Euler angles, is "Polar singularity" the same thing as gimbal lock. In any case, what exactly is a polar singularity, that arises while numerically integrating differential equations involving Euler angles, and how can it be avoided? Thanks, deeptrivia ( talk) 01:13, 3 April 2006 (UTC) PS: I figured out that I'll have to use quaternions and I read about them. How exactly do I make the switch from Euler angles to quaternions? deeptrivia ( talk) 01:35, 3 April 2006 (UTC)
Thanks both of you. I've been solving the same problem I had discussed in an earlier question. My differential equations look like this:
Boundary conditions:
where and are the Euler angles. s is the independent variable w.r.t. which the differentiation is carried out. How can I convert this entire thing to quaternions? Are there any substitutions/transformations I can do? I found a source that says that if the quaternion is {b0,b1,b2,b3}, then it is related to Euler angles by:
Does that mean I just have to make these substitutions into my equations? I'm not even sure how to make these substitutions because inverting these relations will be hard, and will introduce inverse trigonometric functions, which will perhaps have singularity problems of their own. I really appreciate your help! deeptrivia ( talk) 03:11, 4 April 2006 (UTC)
What are Deprit’s variables? I couldn't find a definition anywhere. Thanks :) deeptrivia ( talk) 02:38, 3 April 2006 (UTC)
Thanks. I think it's the second one that I needed. You rock ! deeptrivia ( talk) 03:12, 4 April 2006 (UTC)
I am making a three sided pyramid out of three boards. They will be triangular and the edges will be mitred. I need a formula to calculate the angle of the mitres [based on number of sides (examp.7), angle of slope,length of base...etc.]. If possible, it would be nice to be able to put it on a spread sheet.
Can you help?
--- 70.50.197.126
I believe the answer will depend on the height of the pyramids. For example, with a triangular base, there are 180° inside the base. That makes 180°/3 or 60° between the sides. In the case of an infinitely tall pyramid with a 3-sided base, there would therefore be a dihedral angle of 60°. In the case of a pyramid of zero height, the dihedral angle is 0° (or 180°). Any height in between would have dihedral angles somewhere between 60° and 180°. Do you by any chance want to always use equilateral triangles ? If so, this will give a specific height for each pyramid.
In the case of a equilateral triangle base pyramid with equilateral triangles on the sides, as well, the dihedral angle is 70.53°, and the miter cut angle is (180°-70.53°)/2 = 109.47°/2 = 54.735°. In the case of a square base pyramid with equilateral triangles on the sides, the dihedral angle is 109.47° and the miter cut angle is (180°-109.47°)/2 = 70.53°/2 = 35.265°. In the case of a regular pentagon base pyramid with equilateral triangles on the sides, the dihedral angle is 138.19° and the miter cut angle is (180°-138.19°)/2 = 41.81°/2 = 20.905°. If a regular hexagon is used as a base, then the equilateral triangles would form a flat surface, not a pyramid. A regular heptagon or higher number of sides, used as a base, with equilateral triangles, would have gaps, and not form a pyramid at all. Note that the miter cut angles between the sides and base have not been discussed here. StuRat 02:42, 5 April 2006 (UTC)
To be more specific, the base could have from three sides to eight or nine sides and tapering to a point at the top. The height dosn't matter, it could be from two inches to two km. and same with the base. I'm looking for a formula wherby entering the variables (height, width, number of sides) I can calculate the angle at which to cut the mitres. Thanks --- 74.12.9.227
Thanks, it helps alot. --- 70.50.197.146
Thanks for the update! --- 74.12.2.9
Here's a graphics/geometry question, although fundamentally mathematical.. What's the best way of determining the control points of a cubic Bezier, so that is approximates the curve of a different Bezier? From searching, I've found there's no exact solution. But what kind of approximation is used? -- 130.237.205.132 17:47, 3 April 2006 (UTC)
The article on adjoint functors mentions that the diagonal functor is the left-adjoint of the product functor (this works for any limit), which gives the categorical product of two objects. This seems fishy to me. The categorical product is defined in terms of its univeral property. Thus, it is determined only up to canonical isomorphism. Thus I can't define a a functor here, since I don't have a unique choice of object. So I think this is only a pseudofunctor, not a full-fledged functor. Now, Mac Lane lists these guys as adjoint functors as well, and he makes no mention of pseudofunctors, so my question is, am I totally wrong about this? What's the deal? - lethe talk + 05:20, 4 April 2006 (UTC)
4 digit palindrome number two more than a perfect square
What would the mathematical approach to the problem be? :--) JackofOz 12:41, 5 April 2006 (UTC)
x | (1st digit = 4th digit) in x^2+2 | 4th digit in x^2 | 2nd digit in x | candidates |
32-44 | 1 | 9 | 3,7 | 33,37,43 |
45-54 | 2 | 0 | 0 | 50 |
55-63 | 3 | 1 | 1,9 | 59,61 |
64-70 | 4 | 2 | \ | \ |
71-77 | 5 | 3 | \ | \ |
78-83 | 6 | 4 | 2,8 | 78,82 |
84-89 | 7 | 5 | 5 | 85 |
90-94 | 8 | 6 | 4,6 | 94 |
95-99 | 9 | 7 | \ | \ |
what's up
Help, I posted a question about house numbering here 9 days ago, and now it and its possible answer have glided off the top with now way to retrive them! No link to go back one page of answers! If you see them send it to (email excluded) as who knows, I might not even get back to see the answer to this in time!
Try using a calculator, like the one built in to your computer. StuRat 08:49, 5 April 2006 (UTC)
* * * * * * * * * * * * * 1 2 4 4 2 0 * * * * * * * * * * * * *
Tell me the religious and mathematical significance of the Golden Ratio.
The Golden Ratio is the relationship between the width and length of a rectangle which is most appealing to the eye. It is used constantly in furniture design and different aspects of architecture. The ratio is, W=L×.618. --- 74.12.9.227
Consider a block design : such that the number of points equals the number of blocks : it is thus by definition a symmetric block design.
How can I prove that teh number of points v satisfies with the so-called order of the design
It's really only a subtlety I can't figure out. I know I should consider the equation
and substitute
I would get the result by demanding the discriminant of the resulting quadratic equation in being strictly greater than zero, but not in the exceptional case that the discriminant is exactly zero.
Any suggestions in avoiding this problem would be greatly appreciated.
Consider the number 1983. For 1983 foo = 1+9+8+3 = 21
But is there a special name for summing each individual digit, and if so what is it?
The most obvious thing is that multiples of 3 always sum to a multiple of 3, but you knew that anyway. I think there is a similar effect for 9, (3*3) but not 6.
The last two digits of multiples of 4 are always a multiple of 4, (and there are probably others) but you can answer my original question. — Dunc| ☺ 20:45, 5 April 2006 (UTC)
What is expansion by minors?
Thank you very much for the speedy response! :)
WHAT IS MEASURE OF DISPERSION?
a) A spherical snowball is melting in such a way that its volume is decreasing at a rate of 1cm3/min. At what rate is the diameter decreasing when the diameter is 10cm?. —This unsigned comment was added by 218.111.184.204 ( talk • contribs) .
To solve the equation of
for x, you would take each side the power of zero, right? So you would get
and since any number to the 0 power is 1, x=1.
So,
where y is any number.
Obviously, someone could use this to prove any number is equal to any other number.
Which leads to my final question: What are the restrictions of the transitive property? Does it state when you can't use it to argue certain things (such as the simple -1=1 using square roots proof)? Have the 'rules', if you will, of the transitive property, been agreed upon? 65.31.80.100 12:01, 7 April 2006 (UTC)
65.31.80.100 12:01, 7 April 2006 (UTC)
Well, I am sure this has to be simple, but my mind is all messed up right now. Suppose you have two curves, C1 defined by points (x1i,y1i,z1i) i= 1 to N1, and C2 defined by points (x2j,y2j,z2j) j = 1 to N2. How can I put the curve C2 at the end of C1 to get a smooth curve C3 with N1+N2 points. I have at my disposal a function that can numerically calculate the components of tangent, normal and binormal vectors at all these points (returning three arrays, each of size 3xN.) I guess the values of these vectors at the last point of C1 and the first point of C2 should suffice to find out the required rotation matrix for all points onC2. Any help will be greatly appreciated. deeptrivia ( talk) 02:12, 7 April 2006 (UTC)
On a sphere, a loxodromic arc ("H") travels in a constant direction, whereas an orthodromic arc ("ΔÔ") constantly changes direction. If one defined the loxodromic azimuth as and the orthodromic as , at infinitesimality the arc lengths and azimuths respectively equate. Would the technically proper way to express the azimuthal equity be
Is there such a thing as a fourier transform of a hilbert space? -- HappyCamper 19:30, 7 April 2006 (UTC)
What do you mean? If you consider the space of analytic functions on and make it a hilbert space with the classical integral formula, the fourier transform is a unitary bijective operator. Evilbu 19:47, 7 April 2006 (UTC)
When you evaluate e2πi, you get 1. Therefore
ln e2πi = ln 1
2πi = 0
2 = 0/πi = 0
π = 0/2i = 0
i = 0/2π = 0
How can this be true?
M@$+
@
Ju ~
♠
20:59, 7 April 2006 (UTC)
never quite got how this worked, how would you do it for:
If you could show me how to do it step by step on these specific questions it would be very helpful, oh and show your work (: 21:20, 7 April 2006 (UTC)
The answer to
3) 757 / 14244
is 757/14244 because it is a fraction. Perhaps you are asking about how to turn a fraction into a floating point number. Ohanian 04:52, 8 April 2006 (UTC)
Hi,
I have for quite some time been trying to find a convincing proof that there are infinitely many solutions to a + b = c where c is any number. It seems possible that either a) this is a very axiomatic result which cannot actually be solved, or b) I am simply too stupid/ignorant to be able to locate the relevant proof. Since this is vital to some (hopefully) useful mathematical work I am undertaking (although I wouldn't dare call myself a competent mathematician) any help would be unbelievably appreciated.
Thanks in advance, lynton
What set are you looking for solutions in? If a,b, and c are valued in the set {0}, then there is a unique solution. If they are valued in the group {0,1}, then there are 2 solutions if c is 0 but only 1 solution (up to ordering) if c is 1. Even more pathologically, if you assume that a and b are valued in the negative integers and look for solutions among the positive integers, there is no solution at all. Thus you see that how many solutions there are depends on what space you look for solutions in. Let's assume that you're looking for integer solutions. For each integer n, the ordered pair (n,c–n) forms a unique solution. Furthermore, any solution is of this form. This is all the solutions, and there are infinitely many of them. - lethe talk + 00:09, 8 April 2006 (UTC)
That may be so, but it does not constitute a proof that there are an infinite number of solutions noting my use of the words 'any' number or indeed any mathematical set on which addition is defined. The reason this proof is so essential especially in a cryptographical sense, is that it allows us to establish with certainty that given a member of a set with certain properties, it is impossible to calculate the values of a and b from c. Can anyone think of such a proof? Thanks again.
KSmrq, actually I was intending this proof to be a model for a proof for finite permutation groups, which are, i know, finite. However, all i wanted is a proof that covered say real numbers, and I'm pretty sure that it would go something like:
Set a to half of c and b to half of c. Then, add and take a number to each, until a and b reach their upper and lower limit. However, since you can always add and take a number to a and b, it is impossible for a and b to reach their upper and lower limits, and thus no such limits exist. Vice versa works also, with decrementing a and b incrementing. Therefore a and b have no upper or lower limits, rendering them infinite.
I know the way I have expressed this may not please you 'professional' types out there, but considering that you failed to produce even a rudimentary attempt, and instead stated the *blatantly* obvious, then proceeded to belittle someone, I'd say that any attempt is better than your pathetic contribution. I don't know what rock you come from under, but you mustn't be very proud of it, because you seem to be getting your self-esteem from the internet, of all places. Either help or crawl back home.
Yes, that tirade wasn't in any way pointed at your post, which i only just read enough to comprehend that it was exactly what I wanted in the first place (i read the bits about the more restricted cases and just assumed that the post was going to go on and say exactly what KSmrq did say) and I convey my greatest thanks for it. I think that what KSmrq said was based solely on miscommunication, but even if what i said was dead wrong, I really do not appreciate the insult. Incidentally, would you accept my proof as valid?
Thanks a lot, greatly appreciated.
how can i improve my mathematics? your help might save my life! thx
3 and -3
Thankyou
3 + -3 = 0. - lethe talk + 18:08, 8 April 2006 (UTC)
How about the lowly quadratic (x-3)(x+3)=0? Am I missing something here? —The preceding unsigned comment was added by 84.234.167.166 ( talk • contribs) .
People from Britannica randomly add these articles to create anarchy in wikipedia...
What is the smallest possible measurement of time? 204.112.201.7 20:02, 8 April 2006 (UTC)
If
is the pth symmetric power of an n-dimensional vector space, and
is the exterior power or alternating power, do I have a canonical isomorphism
I think I ought to, but I'm having a hard time writing down such an isomorphism. - lethe talk + 20:14, 8 April 2006 (UTC)
Is considering decision problems in lieu of computational problems sound? The relevant articles use an argument that deciding if x is in language L is equivalent to computing the characteristic function and checking if output is 1. But the characteristic function is defined in terms of the decision problem.
I can't seem to understand why this is sound? Further, if a characteristic function doesn't exist without resorting to using the decision problem, what good is it in showing their equivalence?
Do I understand the proof correctly?
I apologizes for the computer language python, but is the fundamental algorithm for calculating log2(x) aka logarithm base 2 correct?
The numeric value of the binary logarithm of a positive real number can easily be calculated using only the addition, subtraction, multiplication and division arithmetic operators. Here is a sourcecode in python which produces the value.
#!/usr/bin/python from __future__ import division def log2(X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * 2 while X >= 2: integer_value = integer_value + 1 X = X / 2 decfrac = 0.0 partial = 0.5 X=X*X while partial > epsilon: if X >= 2: decfrac = decfrac + partial X = X / 2 partial = partial / 2 X=X*X return (integer_value + decfrac) if __name__ == '__main__': value = 4.5 print " X =",value print "LOG2(X) =",log2(value) # Sample output # # $ python log2.py # X = 4.5 # LOG2(X) = 2.16992500144 #
#!/usr/bin/python from __future__ import division def log3(X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * 3 while X >= 3: integer_value = integer_value + 1 X = X / 3 decfrac = 0.0 partial = 1/3.0 X=X*X*X while partial > epsilon: while X >= 3: decfrac = decfrac + partial X = X / 3 partial = partial / 3 X=X*X*X return (integer_value + decfrac) def log4(X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * 4 while X >= 4: integer_value = integer_value + 1 X = X / 4 decfrac = 0.0 partial = 1/4.0 X=X*X*X*X while partial > epsilon: while X >= 4: decfrac = decfrac + partial X = X / 4 partial = partial / 4 X=X*X*X*X return (integer_value + decfrac) if __name__ == '__main__': value = 4.5 print " X =",value print "LOG3(X) =",log3(value) print "LOG4(X) =",log4(value) # $ python log34.py # X = 4.5 # LOG3(X) = 1.36907024643 # LOG4(X) = 1.08496250072
Ohanian 11:21, 10 April 2006 (UTC)
So, presumably we can generalise to a function giving logN(X):
#!/usr/bin/python from __future__ import division def log(N,X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * N while X >= N: integer_value = integer_value + 1 X = X / N decfrac = 0.0 partial = 1/float(N) X=X**N while partial > epsilon: while X >= N: decfrac = decfrac + partial X = X / N partial = partial / N X=X**N return (integer_value + decfrac)
though as I don't do Python my syntax may be wrong in places ... Would it work for non-integer N? -- Bth 11:49, 10 April 2006 (UTC)
#!/usr/bin/python from __future__ import division def log(N,X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * N while X >= N: integer_value = integer_value + 1 X = X / N decfrac = 0.0 partial = 0.5 X=X*X while partial > epsilon: while X >= N: decfrac = decfrac + partial X = X / N partial = partial / 2 X=X*X return (integer_value + decfrac) if __name__ == '__main__': value = 45.7 print " X =",value print "LOG6(X) =",log(6,value) print " LN(X) =",log(2.718281828,value) # SAMPLE OUTPUT # $ python log.py # X = 45.7 # LOG6(X) = 2.13315367578 # LN(X) = 3.82209829854
I checked the article but it simply said it was derived from the Pythagorean theorem. Don't worry its not homework I'm just curious...
(x1,y1) 1 /\ . . | . . | . . (y1-y0) . _ | 0 . . . . . . .|. \/ <----(x1-x0)----> (x0,y0)
Thanks Bth...but isn't that the same as sqauring the two parts of the slope?
i.e if the slope is 7 over nine, the sum of those squares would be the same thing right?
No, I mean that the 2 components are the same in distance (as you said) so if you sqaured the two components of slope and added them, then took the root of that, would not that be the same thing?
Oh yeah, didn't think of it that way...anyway thanks for the help.
ok, with working out the range, range=highest - lowest, does the lowest include zero.
e.g. if the numbers are 1, 5, 7, 8, 0, 10
would the range be 10-1 = 9
or
would it be 10-0 = 0
i really dont understand and usually i'm pretty good at this whole maths thing.
thanks, skye
Thanks heaps, got lab report due tomoz and was stressin heaps, thanks sooooooooo much, cya, skye
Hi I am trying unsuccessfully to make permutations for a golf trip for 20 players. Over 4 rounds, played in groups of 4, the players should rotate so that none of them plays together more than once. I am sure that there is an easy answer, but we can't find it. Please help. Thank you
abcd|efgh|ijkl|mnop|qrst arol|ebsp|ifct|mjgd|qnkh angt|erkd|iboh|mfsl|qjcp ajsh|encl|irgp|mbkt|qfod afkp|ejot|insd|mrch|qbgl
When talking about a limit, equation, solution, or stuff like that, what is the different between using undefined, DNE, and no solution? And when should I use which one? —Preceding unsigned comment added by 72.59.31.118 ( talk • contribs)
Will you explain to me how to do this problem? I'm doing a makeup assignment from being gone, so I missed the lesson. Also, it can help me do the others once I know how to figure these out. Ok here's the problem
2 over (x-2) squared = 1-1 over x-2
Your help would be greatly appreciated. Also, sorry for the equation form, I don't know how to do all of the math symbols on the computer! Thanks alot! Kirsten (aka 65.101.68.120)
I have a number--> 1.4190792748769801e+26 --> and i want to know what the e+26 part of it means. Do i move the decimal 26 places? help please
Hi,
I have a set of parametric eqations defined as
where
and I have to find the cartesian equation in terms of y. So far I've got
but I cant get any further. I've got a feeling that
comes into it somewhere. Can anyone help?
Whoops - must remember to sign Anand 14:11, 11 April 2006 (UTC)
Quick question for ya'll. I'm an engineering student, and have taken all the required math courses (calc up to diff eq). I'm going to be solving PDEs until I die, I know that already. But what's a "fun" math course to take? Something theoretical? Analysis? Probability? I'd like a broad knowledge of some basic stuff. Even though it does not pertain to my major, I plan on taking relativity next year for some kicks. Thanks in advance! Isopropyl 14:32, 11 April 2006 (UTC)
Should I be able to understand intro level combinatorics or toplogy with my math background? I've only had three semesters of calculus. Isopropyl 20:16, 11 April 2006 (UTC)
I have another idea for a fun math class for you. Differential geometry. Often, a first course in differential geometry is simply a continuation of stuff you learned in vector calculus, the differential geometry of curves and surfaces in R3. Thus it fits your prerequisites perfectly. It's a nice springboard into Riemannian geometry, should you decide to take that at a later date, or general relativity. And you'll learn the Gauss-Bonnet theorem, which may whet your appetite for a topology course. - lethe talk + 21:14, 11 April 2006 (UTC)
I would like to thank you all for your recommendations. However, it seems that I need to take Analysis 1 at my school before I can take anything that's not engineering-oriented applied math (probablity for example). I'll look into your suggestions at a later date. Thanks though! Isopropyl 22:01, 11 April 2006 (UTC)
What is the best way to approach something like y = -4sin (2x + π/4)+ 5? No it's not for homework, any example would be great (anything with a reflection, vertical shift, horizontal shift and all of that together so it's approaching the highest degree of difficulty). Also I was wondering how do you know whether you should graph the x-axis in radians or degrees? Thanks
C-c-c-c 21:22, 11 April 2006 (UTC)
Thanks a lot!
C-c-c-c
01:52, 12 April 2006 (UTC)
I know, but cannot prove, that two consecutive integers are always going to be relatively prime. Does anybody have a proof?
Also, my teacher gave us the following puzzle:
12 1112 3112 211213
And asked us to find the next row (which is 312213). He then said that these triangles can start with any numbers (except 0), and asked us if they will all eventually repeat, or whether some will continue to grow. (A side problem which I have already solved, what is the shortest set of starting numbers that will repeat immediately).
12 34 1112 1314 3112 211314 211213 31121314 312213 41122314 212223 31221324 114213 21322314 31121314 etc. 41122314 31221324 21322314 21322314 etc.
Whereas the Look-and-say sequence goes as follows:
1 11 21 1211 111221 312211 13112221 1113213211 etc.
My question is now, for any starting numbers, will the sequence eventually fall into a loop as shown above for 12 and 34?
tell each gcf you would use to simplify the fractions.
Is there an easier practical illustration of the common terms we use in Electromagnetic Theory like Gradient,Curl,Divergence?
what is the simple low to calculate the distance between the two points on the earth by using geographic Coordinate
Say there is an election in which 100 people vote, and the result is split 50-50. If it was noticed that 20 of the people in favor of the measure owned cats, while 5 of the people against it owned cats, how would I determine if cat ownership was statistically likely to have influenced the outcome of the vote?
Say the vote is run again, with 100 different people, this time including 30 cat owners. Assuming cat ownership is significant, and that there are no other influencing factors, how would I determine the odds of the majority being in favor? -- Serie 21:46, 12 April 2006 (UTC)
Are there any tricks to remembering the unit circle? C-c-c-c 00:34, 13 April 2006 (UTC)
When trying to remember specific cos, tan, sin, sec, csc, and cot values for certain angles (30, 45, 60, 90, 135...etc) C-c-c-c 01:08, 13 April 2006 (UTC)
I'm doing some computer programming and I need some way to compute the digits of an irrational number (specifically, a square root or something like pi or e anything will do). But I need more digits than C or VB can provide with a regular classification, which I think is in the double, 15 digits?? (also I need the program to do it itself, no cheating off the web to get the digits). Is there an easy way without any severe progamming to calculate digits?
I was thinking the only way would be to program a new function that does multiplication and adding longhand, storing each subsequent number from a series like Ramanujan's ( History_of_numerical_approximations_of_π) and adding them longhand, digit by digit, carrying the 10, 100, 1000 etc.
I found this for pi: Bailey-Borwein-Plouffe_formula but I don't think it is applicable. As far as I can tell, the method to compute 16^(n-k) mod(8k+1) described in Exponentiation by squaring still requires that my data will be able to store 16^(n-k). And what about that second term? I don't know enough (or have forgotten enough) calculus to determine what the infitine sum of 1/(16*(8k+1)) from k = n+1 to infinity will equal...but it probably won't affect the rounding of the integer which I assume is the nth digit?
any ideas would be appreciated.
Thanks, - Snpoj 03:42, 13 April 2006 (UTC)
? # timer = 1 (on) ? \p 2000 realprecision = 2003 significant digits (2000 digits displayed) ? sqrt(Pi) time = 74 ms. %5 = 1.772453850905516027298167483341145182797549456122387128213807789852911284591032181374950656738544665416226 823624282570666236152865724422602525093709602787068462037698653105122849925173028950826228932095379267962800174 639015351479720516700190185234018585446974494912640313921775525906216405419332500906398407613733477475153433667 989789365851836408795451165161738760059067393431791332809854846248184902054654852195613251561647467515042738761 056107996127107210060372044483672365296613708094323498831668424213845709609120420427785778068694766570005218305 685125413396636944654181510716693883321942929357062268865224420542149948049920756486398874838505930640218214029 285811233064978945203621149078962287389403245978198513134871266512506293260044656382109675026812496930595420461 560761952217391525070207792758099054332900662223067614469661248188743069978835205061464443854185307973574257179 185635959749959952263849242203889103966406447293972841345043002140564233433039261756134176336320017037654163476 320669276541812835762490326904508485320134192435989730871193799482938730111262561658818884785977875963761363218 634246546641333954355703201522654193952186030497310513829498439659165614245955421226615102478536098095510395600 789402188099613382854025016800745802729119366425192820510001936350073914643295493433951928853735459200563766502 880540575532123189009126322819150914980836695624483100852221923973646324842863261145766932425371577377894414090 544573595351225626391080239236909732127905807617134603914574791879794124850218445145811341888880413220955332184 646709727491028565262707845453262227848800982385836300754950954764062377083388357225436621567481327668384244972 420874516161833205077991480184666814236693651902845463857614827857037774388376297479982737705431583682410998683 228503805526355369722293133805264428410372312043967004307612454138311792278275363715598398376884537027842985707 0905112238405367790133854145853162080730431380697399874366931660138170792720560419548828580630931116362970478678140270
PARI/GP computer algebra system -- GangofOne 06:23, 13 April 2006 (UTC)
I know that Period = 2π/|b|
where b is the horizontal stretch or compression. So for example, 2SinΘ would be 2π/1 = 2π or 360 degrees. Sin2Θ would be 2π/2 = π or 180 degrees.
Now, if I switch this formula around I can have |b| = 2π/period. That means that b must always be positive, something I'm not quite sure of. Now that I think about it I don't think we've ever had a negative b in our tranformation graphing. Does it not exist or is that too complicated for my level (high school)? Thanks.
C-c-c-c 04:41, 13 April 2006 (UTC)
I came up with a proof of the angle bisector theorem (I'm not sure if its' original or not, but I haven't encountered it anywhere else). I'm trying to see if anybody will publish it, but I can't find any appropriate journals. I know that Wikipedia has an article on mathematical journals, and the two big English ones I see are Annals of Mathematics and the Journal of the American Mathematical Society, but the papers in these journals are extraordinarily complex; they're dozens of pages long, use computers, cite references, etc.
Could anyone suggest a mathematics journals that would publish such a simple, geometric proof? Thanks
-- JianLi 18:43, 13 April 2006 (UTC)
Just curious, what's the biggest discovery in the field of mathematics in recent history (excluding prime numbers, etc.)?
OR ?
I believe it is the second, but my friend disagrees. -
Mystaker1
03:08, 16 April 2006 (UTC)
Also, I'm not sure if I understand infinitesimals. Can you tell me whether this equation is solved correctly or not? - Mystaker1 03:31, 16 April 2006 (UTC)
We were doing some stuff on Hilbert matrices in applied maths (really just MATLAB practice) and I was playing around and discovered that . Are they exactly equal? And could anyone give me a hint on proving it? (Just for fun - this isn't homework or anything.) -- 대조 | Talk 11:54, 16 April 2006 (UTC)
Dear Math Ref. desk: I have a really simple question that is really dumb but I have been struggling with it. It is a SAT II Math IC question. I am not posting a homework. Thank you for your help.
5. What are all values of x for which (4−x)2 ≥ (x−2)
The given answer is (C) and the difficulty level is 3. I would like to have some procedure also. I tried to solve it myself but I think I am missing something.
-- Kushal [e-mail address not entered] The preceeding question was added by Kushal one Kushal one 18:11, 16 April 2006 (UTC). Please visit my talk page to resolve any suspicion of trolling by me. I previously used to make (very few) comments under the name "My IP address is not permanent." and variants. Thank you for taking yout time once again.
Correction: Thank you, KSmrq. The parentheses were clearly wrongly put. Signs of a clumsy student... Please read the above question as KSmrq put it. I assure you, however, I did not make that mistake on paper. Thank you I will see your guidance and try to do the problem again. I still think there is something I am missing... Kushal One
STILL HAVE TROUBLE
prove that if N is a normal subgroup of G and H is any complex of G then NH=HN
I read some where that given a long list of multi-digit (random?) numbers, the number 1 will occur as the first digit far more often than 10% (I think it was somewher around 30%...). Can anyone tell me more about this? SigmaEpsilon → ΣΕ 21:24, 16 April 2006 (UTC)
Need assistance with this question, not clear on how to put the monthly summary together to get the total material payments for January. Please email me at e-mail removed; see the note at the top of the page. Many thanks
The Denver Corporation has forecast the following sales for the first seven months of the year:
January $9,000 May $10,000 February 12,000 June 16,000 March 14,000 April 20,000 July 18,000 Monthly material purchases are set equal to 30 percent of forecasted sales for the next month. Of the total material costs, 40 percent are paid in the month of purchase and 60 percent in the following month. Labor costs will run $4,000 per month, and fixed overhead is $2,000 per month. Interest payments on the debt will be $3,000 for both March and June. Finally, the Denver sales force will receive a 1.5 percent commission on total sales for the first six months of the year, to be paid on June 30.
Prepare a monthly summary of cash payments for the six-month period from January through June. (Note: Compute prior December purchases to help get total material payments for January.)
This has nothing to do with mathematics.
Ohanian
04:49, 17 April 2006 (UTC)
I am submitting this with all respect to the respected RD sirs and madams. Please take it with a pinch of salt.
Dear ‘Aklepard’:
I am submitting you my interpretation of the answer. Please use your own mind to see through the problem as my answer may have flaws. Furthermore, please do not forget to check back on the reference desk for other (better) answers by users and administrators that are more informed.
Month Forecasted sales Monthly material payment payment same month Payment next month Labor Fixed overhead Interest payment Commission
December -- 3000 1200 -- 4000 2000 0 0
January 10000 3600 1440 1800 4000 2000 0 0
February 12000 4200 1680 2160 4000 2000 0 0
March 14000 6000 2440 2520 4000 2000 3000 0
April 20000 3000 1200 3600 4000 2000 0 0
May 10000 4800 1920 1800 4000 2000 3000 0
June 16000 5400 2160 2880 4000 2000 0 3000
July 18000 these details here are not required for the present calculation..........................................................................................................................................
[NB: ‘--’‘means ‘cannot calculate’ and ‘0’ means no ‘payment’ necessary.]
Add columns ‘payment same month’ and ‘Payment next month’ to get ‘total material payments’ for that month. FYI, the January figure is USD 1440 +USD 1800 =USD 3240
To get total value of monthly value of cash payments, add columns 3, 4, 5, 6, 7, 8, and 9.
If you are still confused, post your confusion on the reference desk.
Yours truly,
Kushal Hada [contact info removed but ca be found on my talk page.]
PS It is not considered a good idea to post your e-mail address on the RD. I hope you understand.
PPS I apologize in advance if I offended you in any way.
-- Kushal one 00:25, 18 April 2006 (UTC)
So there is an article about Fibonacci Poems at the NYTimes [2]. They introduce the concept of Fibonacci numbers by saying, "Readers of the blockbuster best-selling "Da Vinci Code," of course, may recognize the Fibonacci sequence as the key to one of the first clues left for the novel's hero and heroine" which just shows you how idiotically innumerate the general public is. But anyway, that's not my point. I have a question about this:
Let P be a set of points in general position in the plane. Amen. The last line, said Mr. Venkatasubramanian, is an inside joke in geometry.
Can anybody explain this joke to me? I googled it, and found it again at [3], but with no explanation. JianLi 01:41, 17 April 2006 (UTC)
Can anyone, please, tell me the method of how to resolve these? Thanks in advance.
Afraid the link won`t work therefore it is named after this man
http://img133.imageshack.us/my.php?image=6b7ld.gif
Please Can You tell me the name of this Mathematical Function?
It`s Similar to a wave it`s pink and black.
Which article should I look to search for mathematical formulas in non-euclidian universes, that is not a infinite plane.
More specific, i want to be able to calculate things like shorter distance between two points, pythagorean theorem and point of intersection of two line segments, but all of those in the surface of a sphere.
Thanks -- Alexandre Van de Sande 20:03, 17 April 2006 (UTC)
I have a mac and a pc, a big interest in mathematics and some basic experience on some programming languages. I want to program an application that map networks, wich basically draws sets of lines among a growing point set according to some basic rules.
which program do you recommend, something with a low learning curve. Thanks
please can someone please give me the stepwise linear regression equation.
I'm looking for the equation for the circumphrance of a certain longitude; for example, the circumphrance of a smaller circle that's 45 degrees above the exact middle of a spere. Tell me if I need to be clearer than that. Jonathan talk 19:31, 18 April 2006 (UTC)
Are you sure about that? I tried that formula and kept getting negative numbers. (For instance, 2 times pi times 10 times the cosine of 10 equals: -52.7204.) Jonathan talk 00:29, 19 April 2006 (UTC)
I'm trying to find out the function to draw the terminator line on a plate carrée projection of Earth's surface. Thing is, I have a map with the continents and everything, and I want to generate the terminator line of the given period of the year and use it to create a shadow layer over the map. The time of the day part I can figure by myself. Oh, and it doesn't have to be utterly precise, just good enough.
Anyway, this proved to be a tricker than I thought. As you probably know, Earth axis has a tilt (23.45°), so the terminator isn't a simple meridian line, but a curve, and depending of the time of the year this curve changes. Can anyone help? ☢ Ҡi∊ff⌇ ↯ 20:46, 18 April 2006 (UTC)
A circle is drawn. Two points are marked on its sides. We join the 2 points. Thus, we divide the circle into two parts. Into how many parts can the circle be divided for "n" no. of points?. Find the formula
I worked it out on paper and it looks to me like your formula is:
Because when I used 2 points I got 2 section; 3 points = 4 sections; 4 points = 8 sections; 5 points = 16 sections... Jonathan talk 21:13, 18 April 2006 (UTC)
1 | = 1 = 1 1 1 | = 1+1 = 2 1 2 1 | = 1+2+1 = 4 1 3 3 1 | = 1+3+3+1 = 8 1 4 6 4 1 | = 1+4+6+4+1 = 16 1| 5 10 10 5 1 | = 5+10+10+5+1 = 31 1 6| 15 20 15 6 1 | = 15+20+15+6+1 = 57 1 7 21| 35 35 21 7 1 | = 35+35+21+7+1 = 99 1 8 28 56| 70 56 28 8 1 | = 70+56+28+8+1 = 163
If we add all the numbers on the right hand side of the line per row, we get 1, 2, 4, 8, 16, 31, 57, 99, 163. -- Alexs letterbox 23:06, 18 April 2006 (UTC)
I'm not quite sure how to ask this, so bear with me. I'm looking for a field of mathematics/analysis that I've never heard of or run across, that I can't think of a name for, but that I'm certain must exist somewhere. I'm trying to solve a problem that involves taking a set of objects (one-digit numbers), arranging combinations of them within a structure, and finding a particular combination that satisfies certain criteria. It would have to be able to deal with a situation where 1)There are too many possibilities to try every one (unlike Anagrams), and 2)There's no obvious series of deductions that solves it one piece at a time (unlike Sudoku). A bit like a Magic Square, really, though apparently there are formulas that solve most of those. Any ideas? Black Carrot 21:07, 18 April 2006 (UTC)
Hi, I have a Java program to do that I just can't crack.
These are the instructions given:
Create a class called Sentence with the methods as listed below. This class has one String field called aSentence that holds several words separated by spaces. Your client class used to test these methods called RunSentence should use file input. Use the file in the pickup folder called “sentence.txt”
//create a constructor method, a mutator method and an accessor method
//purpose: the method should return the number of words in the sentence
public int numWords( )
So, the question asks for the number of words. I thought about this and assumed: number of words is number of spaces plus 1. For example "This is a sentence", has three spaces, and 4 words, and so on ( I don't think we have to worry about two spaces in between, just started strings not so long ago).
aSentence is my string here, n keeps track of the spaces and I've set n to 1, because if anything is written there will always be something (ie. one word). I have no syntax erros but the debugger isn't working for me so I have no idea what's wrong with it. Int index gives me an integer value of how long the string is. I've set position to 0 so that it counts from the first index. The repition statement is position == index, so once I get position to equal index, I'm at the very end of the string.
In the first part of the for loop, position is 0, and it checks for where " " is found. So then position becomes 4, and it adds one to n because it found a space, therefore a word. Next it does it pretty much the same thing, but adds one to the that 4, which then becomes 5. After it does aSentence.indexOf ( " ", 5) it becomes 7, where 7 is the next space. Then it adds 1 to that 7 and starts again. I have it add this one to stop it counting the space twice, if that makes any sense to anyone.
If anyone has any idea about any of this, please help thanks.
public int numWords() { int n = 1; //counts number of spaces int index = aSentence.length()-1; for ( int position = 0; position == index; position = position + 1) { position = (aSentence.indexOf ( " ", position)); if ( position != -1) { n = n +1; } position= (aSentence.indexOf( " ", position+1)); if ( position != -1) { n = n +1; } } return n;
}
C-c-c-c 06:05, 19 April 2006 (UTC)
I see several problems with this code. For one, you shouldn't change your position variable inside a block of code whose termination rests on position reaching the length. For example, it looks like if you feed that code a string with no spaces, it will set position to -1 on the first pass, and never terminate. If all you want to do is count the number of spaces, then why don't you just do
n=0; for (int i=0;aSentence.length()-1;i++) if (aSentence[i]==' ') n++;
- lethe talk + 07:39, 19 April 2006 (UTC)
public class StringUtilities { // name arbitrary; would be combined with other such functions public static int countWords(String s) { int ret=0; boolean wordstart=true; for(int i=0;i<s.length();++i) { if(s.charAt(i)==' ') wordstart=true; else if(wordstart) {++ret; wordstart=false;} } return ret; } }
This handles multiple spaces properly, as well as spaces at the beginning or end of the string. It's still a very naïve definition of a "word" counter, though. -- Tardis 19:21, 19 April 2006 (UTC)
WordCountableString extends String
or so. Certainly some strings cannot be said to contain words, for instance "+!@#($!*(%@@^"
or "42"
, depending on your definition of "word". But because it's entirely fair to say that such strings have 0 words, the function that gives the number of words in is well-defined for any , given a suitable unambiguous definition of "words" and boundaries between them. So what we'd really want is some sort of
aspect-oriented programming approach where we embued all Strings with the capacity to report on their own word counts.String
functions on a "fake subclass") would seem to naturally extend to having a FirstLetterMayBeUppercaseString
class which supports the boolean beginsWithUpper()
function. And then why not (supposing
multiple inheritance, while we're invalidly subclassing String
anyway) have WordCountableStringPerhapsWithInitialUppercaseLetter
that extends both of these? I don't think that the notion of defining arbitrary functions on Strings is possible to fit into the usual OOP model. Thus my simple suggestion of a utility function, since that's what's being requested (a function).WordCountingReader extends FilterReader
with the obvious semantics. Then you're adding behavior to a well-defined object, rather than simply defining a function of a well-defined object. Seems like a better fit to me. (Sorry this is so long, and again if I'm misunderstanding you!) --
Tardis
21:54, 19 April 2006 (UTC)solve for x and y:
m/x +n/y = a p/x +q/y = 0
solve for x and y:
m/x +n/y = a p/x +q/y = 0
becomes
solve for U and V:
mU + nV = a pU + qV = 0
x = 1/U and y = 1/V
very easy. Ohanian 02:22, 20 April 2006 (UTC)
Numerous papers (such as this) explaining Rand index (for which there's no Wikipedia article) use a bracket nomenclature similar to that of column vectors but with normal parentheses () rather than square brackets []. I can't understand what this bracket nomenclature is referring to. The worked example is:
Can anyone explain to me how this answer is achieved? I'd be most grateful!! └ UkPaolo/ talk┐ 19:52, 19 April 2006 (UTC)
A bridge needs to be suspended over a river. The bridge will be one mile in length. If a (one mile + 2 feet) cable is used as the suspension cable, what is the largest type of animal that will be able to cross under the suspension cable at the mid-point of the bridge?
Choices:
How do I solve this?
Thank you for your help.
-- User:Archie44 10:20, 20 April 2006 (UTC)
I would say it couldn't support any weight, because to use a 5282 foot cable to span a 5280 foot gap, you would need to exert an enormous amount of tension to prevent it from sagging more in the middle. This tension would be so high that any materials we have would fail under such a stress. StuRat 07:28, 21 April 2006 (UTC)
I'm not sure if this comes under maths or science, but I'll try it here: sand is falling onto a conveyor belt at a rate of 0.2kg/s. The conveyor belt is moving at a rate of 3m/s. There are four questions:
These are fairly straightforward. Since force is , the answer to the first part is clearly 0.6N. For the second, we see that 0.6N is applied over 3m every second, so the rate of work is 1.8W. For the third, there's 0.2kg of new mass every second, which will add of kinetic energy every second, i.e. 0.9W. I can't for the life of me explain 4, though---where the extra energy every second is going, if not being stored as kinetic energy. I've considered examining the centres-of-mass (consider the 0.2kg being dropped at one point - it takes 0.9J of work to spread that out over 3m, and another 0.9J to accelerate it to 3m/s), but this falls down because you get the spreading for "free" (I think). This isn't homework. Any help definitely appreciated. -- 83.147.171.12 10:57, 20 April 2006 (UTC)
Do we have an article that covers how to factorize integers in polynomial time, or whether this is possible, or the repercussions on the entire computer security systems we use if this mathematical breakthrough happened, or if somebody is attempting to solve this problem?-- Sonjaaa 14:36, 20 April 2006 (UTC)
What is the logic behind the size of ID Card as 85.6 mm x 53.98 mm ? —Preceding unsigned comment added by 202.70.64.15 ( talk • contribs)
The ratio of the sides is related to the `golden mean', thought by the Greeks to be the most pleasing ratio of sides in a rectangle See http://goldennumber.net/creditcard.htm
A quick question regarding vectors and sets. Is the length of a vector written or , or can it be either? Which is most commonly used? What about a set , does that have size or (or either)? I'd be grateful if someone could clarify this for me! └ UkPaolo/ talk┐ 18:20, 20 April 2006 (UTC)
I have several computer programs that I installed on my computer - but every time I try to use these programs it say I have to have the CD in the drive before it will run. Is there a way to completely install these CD's and then point the program to the full install rather than the CD drive? Thanks for you help in advance Maria
Please can someone explain to a non-mathematician why prime numbers are needed to create keys for RSA cryptosystems. Wouldn't any sufficiently large number be o.k.?
Thanks for your help guys, I still don't think I understand. Probably because I stopped learning maths aged 14 (now 29). Please can you recommend a good primer on this? EmperorMoo 20:53, 21 April 2006 (UTC)
Thanks everyone, I think I'm going to have to read more maths background before I'm able to understand. EmperorMoo 12:48, 23 April 2006 (UTC)
O genius Wikipedians, I pray to thee to give a helping hand to a fellow bemused user. This is a homework question, I apologize - but I'm not asking for the answer (as it is given), but more so the best way about going about the question in order to get the answer. If possible pls put this into proper Maths syntax, and give me a link to how to write in maths syntax:
A person wishes to walk from (0,0) to (1,1) in the x-y plane in the shortest possible time. The nature of the ground is such that the max. speed of walking is given by "v=v0(1 + αy)" where v0 and α are constants. Show that the path taken is the integral between 0 and 1 of √(1 + (y′)2) / (v0(1 + αy)). The next bit of the question is "Show that the path taken should be an arc of a circle with centre on the line y = −1/α". Please give me a nudge in the right direction. All help is completely appreciated. -- Dangherous 13:31, 21 April 2006 (UTC)
I am having trouble with a specific problem from my statistics homework. I'd appreciate any help given.
Suppose you own a basketball team. Suppose also that in the NBA the average salary of players is $5,000,000. The lowest salary you can offer is $385,000. You plan to sign 15 players.
Construct a set of 15 data elements that have a mean of $5,000,000 spending the least amount of money possible.
Is there a formulaic way to solve such a problem? Or is the only way to fiddle around with various numbers? -- Impaciente 02:25, 22 April 2006 (UTC)
What does the "kis" particle mean in the names of the following geometric figures (and others)?
I've noticed that all the figures in question have triangular faces, but I don't understand what the number (tria, tetra etc) represents. -- 72.140.146.246 03:34, 22 April 2006 (UTC)
Thank you. This is exactly what I wanted to know. But what about "disdyakis"? -- 72.140.146.246 12:55, 22 April 2006 (UTC)
Thanks. I did some investigation, and found that the disdyakis dodecahedron can be formed from a rhombic dodecahedron by quartering each face and raising the center point (as tetrakis). It was the rhombic part that got me. -- 72.140.146.246 20:56, 24 April 2006 (UTC)
See http://en.wikipedia.org/wiki?title=Talk:Catalan_solid and http://en.wikipedia.org/wiki/Conway_polyhedron_notation
(No question.)
Try Poisson distribution. linas 00:28, 23 April 2006 (UTC)
A 20 kg box rests on a table. What is the weight of the box and the normal force acting on it? b) A 10 kg box is placed on top of the 20 kg box. Determine the normal force that the table exerts on the 20 kg box and the normal force that the 20 kg box exerts on the 10 kg box.
First I did: a)
W = mg W = 20(9.81) W = 196.2 N (DOWN)
ΣFy = ma
Since there is no movement in the vertical direction, Fy = 0
FN - FG = 0 FN = FG FN = 196.2 N (UP)
This part was easy, but my question concerns the second part. I did:
b)
ΣFy = ma
This equals zero again...and this where I'm unsure (FN2 = 10 kg object, FN1 20kg object)
FN2? + FN1 - FG = 0 FN1 = FG - FN2 FN1 = 9.91(20) - 9.81(10) FN1 = 98.1 N (UP)
And the second part of part b...
ΣF = ma FN - FG = 0 FN = FG FN = 10(9.81) FN = 98.1 N (UP)
I'm not sure about this, that's what I have up there so if anyone can point me in the correct direction or explain to me why I'm right (I think I am, but I am not sure, and I need to be sure of the concept) it would be greatly appreciated. Thanks
C-c-c-c
04:02, 23 April 2006 (UTC)
Right, I changed that. So, wait, have I done it right? I'm starting to think I haven't since I didn't include the FG for the 10kg box in the first part of question b. Instead should it be:
ΣFy = ma FN1 + FN2 - FG1 -FG2 = 0 FN1 = FG1 + FG2 - FN2 FN1 = 9.81(20) + 9.81(10) - 9.81(10) FN1 = 196.2N (UP)
This doesn't seem right either, since it's the same as up top.... Help, utterly confused! C-c-c-c 04:26, 23 April 2006 (UTC)
Isn't that what I have there? I have FN2 = 9.81(10) C-c-c-c 04:44, 23 April 2006 (UTC)
Yes, but you have FN1 + FN2 - FG1 - FG2 = 0. Why should the sum of those forces be zero if they are not all acting on the same object? — Keenan Pepper 04:53, 23 April 2006 (UTC)
But isn't that an entire system, can't you do it like that too? C-c-c-c 04:55, 23 April 2006 (UTC)
Oh, I didn't know you didn't include internal forces. Okay that makes sense, thank you so much for you taking the time to going back and forth and helping me, I appreciate it! Thanks a bunch again.
C-c-c-c
06:08, 23 April 2006 (UTC)
After explaining the process of determining the checksum of an ISBN, the ISBN article says, "Since 11 is a prime number, this scheme ensures that a single error (in the form of an altered digit or two transposed digits) can always be detected." How does 11's being prime affect its usefulness for checksumming? 139.55.22.138 19:54, 23 April 2006 (UTC)
How can I compute E[Max(X,Y)] (Mathematical Expectation)?! Armandeh 22:07, 23 April 2006 (UTC)
Does anyone know what the control sequence for Vinogradov's version of the big O notation is? The closest I can find is , but the right "<" should be cut off where the left one ends. Often found in books on analytic number theory. Mon4 00:16, 24 April 2006 (UTC)
Hello. I'm a beginning programmer. Two years ago, I tried to learn Visual C++ .NET. That was really, really hard. I wasn't able to do anything besides the tutorial in the book, so I quit. About four months ago, I picked up Liberty BASIC. I am able to do a lot and understand the language. I really enjoy it and am doing a lot of fun stuff. I wondered if anyone had any suggestions on other languages to try next or any suggestions about a good progression of languages for a learning programmer. Any stories about what you did, what you wish you did, or just simply any advice you have would be great. Thanks for your help. -- Think Fast 01:23, 24 April 2006 (UTC)
A lot depends on what you want to do. Different programing languages are better at different tasks. Do you want to write
In terms of your programming development getting some Object-oriented programming under your belt is a good idea. You might like to look at Slashdot where the pros and cons of different languages are endlessly debated. -- Salix alba ( talk) 10:12, 24 April 2006 (UTC)
Can you please explain how this formula was formulated?
(141.5/SG at 60degF)-131.5
this formual is used to calculate the API gravity of cude oil.
thanks
thank you Melchoir....... anyone has more??
O genius Wikipedians, I pray to thee to give a helping hand to a fellow bemused user. This is a homework question, I apologize - but I'm not asking for the answer (as it is given), but more so the best way about going about the question in order to get the answer. If possible pls put this into proper Maths syntax, and give me a link to how to write in maths syntax:
A person wishes to walk from (0,0) to (1,1) in the x-y plane in the shortest possible time. The nature of the ground is such that the max. speed of walking is given by "v=v0(1 + αy)" where v0 and α are constants. Show that the path taken is the integral between 0 and 1 of √(1 + (y′)2) / (v0(1 + αy)). The next bit of the question is "Show that the path taken should be an arc of a circle with centre on the line y = −1/α". Please give me a nudge in the right direction. All help is completely appreciated. -- Dangherous 13:31, 21 April 2006 (UTC)
Following on from this, how would I show that the path taken should be an arc of a circle with centre on the line y = -1/α? When I've tried this, I've done about 5 pages of working out, which is far too much I'm sure. What's the quickest way to get to the answer? Thanks awfully. -- Dangherous 11:26, 24 April 2006 (UTC)
The Euler-Lagrange equation for is
with the boundary conditions . Multiply by ,
Integrate,
Can anyone check my math and finish it from here? ( Igny 12:59, 24 April 2006 (UTC))
Thanks for checking the steps so far. The previous equation is equivalent to
where . Then solving it for results in
Denote and get
Integrate,
This looks like a circle. The unknown constants can be found from the boundary conditions on y. The center is on the line . Again I am not 100% sure I got all the steps right.( Igny 02:45, 25 April 2006 (UTC))
I have a huge number of equations in Latex, and I need to make a presentation in Powerpoint. Is there a way to convert equations from Latex to the equation editor format used in Powerpoint? I seriously hope there is! Thanks :) deeptrivia ( talk) 14:06, 24 April 2006 (UTC) PS: I know about Texpoint, but it doesn't seem to work for me. deeptrivia ( talk) 14:10, 24 April 2006 (UTC)
They also look a lot like Powerpoint.
Another approach is to use TeX4ht to convert to OpenOffice format (which stores the equations in MathML). OpenOffice can then export the document in MicroSoft formats, although it also includes a presentation package of its own ( Impress). -- Avenue 10:32, 26 April 2006 (UTC)
Solve this simultaneous equation?
Find the value for a + t if:
You may use this equation to help you:
The web can solve it for you. http://home.ubalt.edu/ntsbarsh/Business-stat/otherapplets/SysEq.htm
Ohanian 23:24, 24 April 2006 (UTC)
What kind of stupid exam question would ask for a+t? And if you know a and you know t then logically you would know a+t, it sounds like an exam question purely for the sake of an exam question without any real use in real life. Ohanian 03:09, 25 April 2006 (UTC)
Does the surface with equation z = xy have a name? I'm curious because it looks a little like a hyperbolic paraboloid, and the equation is similar to the reciprocal function xy = k (ie y = k/x), which is a hyperbola. -- 72.140.146.246 01:00, 25 April 2006 (UTC)
The group theory I did in my computer science courses is getting amazingly rusty. I know that is the group of all of the numbers from 1 to (p - 1) under multiplication, and has a lot of nice properties, but I can't remember the other names for it. Could someone point me to the article on that group? I'll be happy to create some redirects from Zp* or Z_p^*, to make finding the article easier. Thanks! -- Creidieki 01:01, 25 April 2006 (UTC)
Long, long ago, when the Internet was still young and lived under the name of Sanders (or at the very least with a sign out front reading "COMMERCIAL INTERESTS WILL"), I obtained undergraduate degrees in computer science and applied mathematics. In the case of the math degree, I'd already completed some advanced coursework in high school, so I entered college taking courses in linear algebra and differential equations. None of that is intended to impress anyone; in fact, just the opposite, because after I wasted the next ten years trying in vain to convince myself that a lucrative career in the computer industry was the route to happiness and financial success, I finally gave up (just wasn't good at programming for a living -- I'm too social). Before long I found myself tutoring at the local community college, and I've discovered that while I'm very good at helping students learn pre-algebra, algebra, and geometry, when the topic turns to more advanced matters, like trig or calculus, I start to falter... and pretty much everything I learned in college I've now forgotten. Diff EQ's, Linear, abstract, even advanced calc -- gone from, or buried somewhere in, my brain.
Now I'm considering teaching math for a living, preferably at the high school level, and I have a feeling I'm going to have to pursue an advanced math degree at some point. But I don't have any of my old textbooks, which makes it harder to re-learn all that stuff. And that brings me to my question: besides the Wikibooks and the stuff in this portal, which strike me as neither complete (yet) nor conveniently set up for structured learning (yet), where can I go online, or what books should I buy? If I need to start investing in textbooks again (my wallet trembles at the idea), which ones do you recommend?
Thanks for any advice you can offer! -- Jay (Histrion) ( talk • contribs) 20:02, 25 April 2006 (UTC)
Hi, i'm currently doing a maths degree (although i'm guessing on the other side of the atlantic) and i find that the schaum's outline series are very helpful and very cheap. they are appaulingly edited but all things considered they're superb.
Let's say Q = arctan(.5*tan(P)). Generally speaking,
However, if P equals either 0 or 90°, then Q = P. Now consider
If Pm = 45°, Qm ≈ 26.565°. If you wanted to integrate between Qf and Qc, but using even spacing (i.e., so that Qm = .5*[Qf + Qc]), how would you define/describe it? Does either the integral or interval have a special name?
~Kaimbridge~
12:47, 26 April 2006 (UTC)
Which type of image has a better resolution and is sharper? Patchouli 05:06, 27 April 2006 (UTC)
Thank you. Patchouli 06:51, 27 April 2006 (UTC)
What are affine varieties and how do they relate with grobner bases? Is there any other type(s) of varieties apart from affines if there what are they and how do they differ from the affine varieties? —The preceding unsigned comment was added by Nkomali ( talk • contribs) .
If sine can be defined within a triangle,how about sine hyperbolic?? —The preceding unsigned comment was added by 210.212.194.215 ( talk • contribs) .
In Matlab, is there a loop-free way to create an nxn matrix with diagonal and upper-triangular entries equal to 1, and lower-triangular entries equal to 0?
eg. for n = 3:
[ 1 1 1; 0 1 1; 0 0 1]
Confusing Manifestation 12:45, 27 April 2006 (UTC)
repmat(1:n,n,1)'<=repmat(1:n,n,1), triu(ones(n)),
cumsum(eye(n), 2), fliplr(hankel(ones(1,n))), inv(eye(n) - diag(ones(1, n - 1), 1)), !!(eye(n) + diag(ones(1, n - 1), 1))^n,
Thanks for all of those suggestions. I'll use Jitse's version just because at a quick glance it seems to be fairly simple, although it's nice to know the alternatives exist. (First rule of Matlab: there's almost always at least one loop-free way to do something.) Confusing Manifestation 00:31, 28 April 2006 (UTC)
Is the continuos image of a complete metric space necessarily complete? (Prove or give counter example) Nkomali.
What are the properties and applications of groebner bases. --Nkomali Nkomali 14:07, 27 April 2006 (UTC)
Show that the spaces l power alpha, the set of all bounded sequences aaaa9 in R or C with norm xn = sup{\xn\}, is a normed linear space. Show also that l power alpha is a complete normed linear space with the transition invariant d(x,y) = sup subscript j in N absolute value of the difference between epsilon j and mu of j.-- Nkomali 14:26, 27 April 2006 (UTC)
hi, can anyone explain to me what does the 'unpredictable, yet deterministic' behaviour of things in chaos theory means?... I don't get it :|, how can something be 'unpredictable yet deterministic'? If we find it's deterministic, aren't we somehow making it predictable?.-- Cosmic girl 15:55, 27 April 2006 (UTC)
Thank you! :) -- Cosmic girl 19:41, 27 April 2006 (UTC)
If I have a random variable Z = aX + bY, what is the characteristic function of Z in terms of the pdfs of X and Y? -- HappyCamper 16:34, 27 April 2006 (UTC)
I HAVE A RECTANGULAR TANK MEASURING 55 METRES BY 48 METRES CONTAINING 33 LITERS OF WATER. HELP ME FIND THE DEPTH OF THE WATER. —Preceding unsigned comment added by 208.131.187.81 ( talk • contribs) 02:22, 28 April 2006
Convert the volume from units in litres to units in metre cube and the answer is as plain as daylight. Ohanian 09:15, 28 April 2006 (UTC)
Do you perhaps mean centimeters (cm)? You could always convert to chains and hogsheads.... Skittle 23:24, 1 May 2006 (UTC)
How would you go about doing the question below...
All I could think of was changing 2sin²θ-1 into -2cos²θ + 1. I can't change sinθcosθ (at least I don't think so). I tried the right hand side next, and I got:
By the way, I keep on getting Failed to parse (lexing error) whenever I try to properly write a fraction, I just copied and pasted one from this page and changed it to this question but it still doesn't work, sorry about that. Thanks
C-c-c-c 03:34, 28 April 2006 (UTC)
How much money do I need to retire? And what % return can I expect to get from investing?
If I can achive X% Average return, does that mean I can always take out X% of the princaple each year? 12.183.203.184 03:52, 28 April 2006 (UTC)
How to calculate various interest rate problem ----------------------------------------------
extremely long post cut by me. For full version, see this diff. - lethe talk + 09:25, 28 April 2006 (UTC)
What are duplex numbers? Ohanian 09:06, 28 April 2006 (UTC)
Some board games or maps use squares (4 exits from every cell, or 8 if you include diagonals, but the latter are not the same distance away as the former), some use hexes (6 equidistant exits), some use triangles. Is it possible for a map to use other shapes, and allow other numbers of possible equal exists besides 4, 6 or 3? Is it possible to have with 8, for instance? Or why is it impossible? The shape doesn't have to be symmetrical, but ideally the exit points should be as equidistant as possible from the centre of one to the centre of another.-- Sonjaaa 10:28, 28 April 2006 (UTC)
Dear Wikipedians. I'll be very pleased if I'll the solution for the following geometrical rider: ABC is a triangle in which angle B = 2 angle C. D is a point on BC such that AD bisects angle BAC and AB=CD. Prove that angle BAC=72 degrees.
Thank you very much. User Akshitapatel
Hello fellow Wikipedians. Today I had the unfortunate task of writing a trig test (but I don't think it went too bad for that matter), and the question below stumped me.
Use only sec x:
I didn't know what to do, and I looked at all the formulas on the formula sheet to see how I could convert sin x into anything, but alas, nothing. The question below has to be in terms of sec x, that's the challenging part. I spent a good deal towards the end trying to think this through, and all I could come up was converting sin x into 1/cscx, but that didn't help either. Also, I converted sin 2x into 2sinxcosx (edited) I believe or something similar, I don't know it off the top of my head. Any thoughts on this would be greatly appreciated. --- C-c-c-c 22:52, 28 April 2006 (UTC)
I have an OT question—I've just recently administered my first final exam as an instructor in Canada, and have come across this usage of "write an exam", which confuses me a little. If the student writes the exam, just what is it the instructor does, when creating it? Isn't that also "writing", or is there a different verb used? -- Trovatore 23:55, 28 April 2006 (UTC)
Right, never mind, I did confuse it, but I think it was 2sinxcosx I had on the bottom, whatever it was, I got it from the identity sin 2x on my formula sheet. ---
C-c-c-c
02:44, 29 April 2006 (UTC)
So, you got as far as:
What did you do next? Melchoir 04:23, 29 April 2006 (UTC)
Today we started learning trig in my geometry class (our teacher calls it plain-vanilla trig, as it does get harder) and we learned the simplest of rules. We took notes, started on homework with extra class time, etc. When I got home to finish, I found some one had taken my notes and homework (while it is entirely possible I just lost them on the floor at school somewhere, I will stick with them being stolen). What I need to do is just make sure I'm sure. Sine=Opposite side/Hypotenuse; Cosine=Adjacent side/Hypotenuse; Tangent=opposite side/Adjacent side; Area= (1/2)(angle a)(angle b)(sinC). I pretty sure about all but the last one. If any corrections are needed please help me. Thanks. schyler 00:05, 29 April 2006 (UTC)
Thank you. Now that you mention it, my teacher did tell us this story about an indian princess named Sohcahtoa. I forgot. Also, that is the formula I was thinking of. Again, thanks. schyler 01:32, 30 April 2006 (UTC)
I have been looking through the proofs of the rules of differential calculus, and I understand how we find d/dx(x^n)=nx^(n-1) (something I was taught to take for granted), as well as the quotient rule and d/dx(sin x) and d/dx(cos x). However, I reached a stumbling block with the proof of the Chain rule. From the first line:
I assume this was reached by:
Where did the epsilon(delta) come from?
Also, in the proof of the product rule (which is more clearly laid out), it is said that:
I assume this is done with some sort of factorisation, but nothing I can see. The two terms on the left have no common factor. What am I missing?
Thanks in advance. -- Alexs letterbox 05:00, 29 April 2006 (UTC)
Hi,
I would like to know the difference between Absolute Graph and Relative Graph? I have searched all over the internet and i havent found any information. Its not even in my college notes. Any help would be appreciated as i have no idea what absolute and relative graphs are!
Please help me out. Thanks!
Its for my assignment for Quantitative Maths. I am stumped at it too!
Hey thanks alot. Atleast that gave me some idea. Maybe i will be able to expand on it but any new info is always welcome. thanks!
If you gave us some context, we might be able to make good educated guesses. What course is this for? - lethe talk + 09:19, 29 April 2006 (UTC)
Quantitative Maths. I have my asked my instructor and hopefully she will respond quickly. Its an online course.
Hi is the Newton who created the Newton-Rapson Method (for finding roots of an equation) Sirr Isac Newton. (the apple one)
Hello, everyone. I'm interested in making my own "book on tape" type of project, except on a CD which is made with my computer. Does anyone know what I would need to do this and what software I could use, preferably downloadable for free from the internet from a site such as tucows? Thanks. -- Think Fast 01:13, 30 April 2006 (UTC)
Say shoppers enter a shop at a mean rate of 4 per minute. This can be modeled as an exponential distribution parameter 0.25. How do you show that the difference in times between successive shoppers entering is distributed exponentially as well? Is this to do with Exponential distribution#Memorylessness? x42bn6 Talk 12:53, 30 April 2006 (UTC)
Are there any formal names for 3-focus, 4-focus, etc. ellipse-like shapes?
Tuvwxyz 18:53, 30 April 2006 (UTC)
i need help find it some definitions for word like PI,ratio ect where i can look?
could u please list out about thirty-fourty applications of infinite series-- 61.1.252.99
{ 10 [3(squared) + 2/4 - 5/8 ] - 9 }
I just want to know if i got the anwser right, because I was bored and I made it up... also, I don't know how to write the squared symbol, sorry. :| . -- Cosmic girl 15:33, 1 April 2006 (UTC)
Cool! I got it right! lol...(I'd be really stupid if I didn't though). thank you Keenan, and Kieff. XD. -- Cosmic girl 16:00, 1 April 2006 (UTC)
An object cools at a rate (in °C/min) equals (1/10) of the difference between its temperature and the surrounding air. If a room is kept at 20 °C and the temperature of the object is 28°C, what is the temperature of the object 5 minutes later?
I think the object's temperature=f(t)=8*exp(k*t) +20, where 8=temperature difference of the object and the surrrounding and 20=the surrounding temperature.
I don't understand where comes into play.
Patchouli 19:47, 1 April 2006 (UTC)
In computational complexity theory, what's the difference between a function problem and a computation problem? Both terms seem to be used fairly similarly. The computation problem article leaves me very confused. -- Creidieki 20:59, 1 April 2006 (UTC)
Hi, this is going to sound insane, but over on Lostpedia, we're working on deciphering the blacklight map on the back of the blast door, as displayed in the most recent episode "Lockdown." There's an equation we'd like to display, but Wikisyntax math markup is making my head spin. Could someone show me how to display the following on a Wikipage? Thank you! jengod 22:37, 2 April 2006 (UTC)
=2rcos[?]
=r*((sqr(5)-1)/2)
-72' = 4rcos"2(72') = r*((sqr(5)-1)/2)
You ROCK!
Thank you. Seriously, you're a star. The original image, enhanced can be found here. I can't make heads or tails of it, but someone broke it down as above. There are also a couple of vector-y equations on the right side of the map. Anyway, THANK YOU.
If you want to join in on the deciphering fun, check out http://lostpedia.com/wiki/Blast_Door. 71.106.0.109 01:01, 3 April 2006 (UTC)
With reference to Euler angles, is "Polar singularity" the same thing as gimbal lock. In any case, what exactly is a polar singularity, that arises while numerically integrating differential equations involving Euler angles, and how can it be avoided? Thanks, deeptrivia ( talk) 01:13, 3 April 2006 (UTC) PS: I figured out that I'll have to use quaternions and I read about them. How exactly do I make the switch from Euler angles to quaternions? deeptrivia ( talk) 01:35, 3 April 2006 (UTC)
Thanks both of you. I've been solving the same problem I had discussed in an earlier question. My differential equations look like this:
Boundary conditions:
where and are the Euler angles. s is the independent variable w.r.t. which the differentiation is carried out. How can I convert this entire thing to quaternions? Are there any substitutions/transformations I can do? I found a source that says that if the quaternion is {b0,b1,b2,b3}, then it is related to Euler angles by:
Does that mean I just have to make these substitutions into my equations? I'm not even sure how to make these substitutions because inverting these relations will be hard, and will introduce inverse trigonometric functions, which will perhaps have singularity problems of their own. I really appreciate your help! deeptrivia ( talk) 03:11, 4 April 2006 (UTC)
What are Deprit’s variables? I couldn't find a definition anywhere. Thanks :) deeptrivia ( talk) 02:38, 3 April 2006 (UTC)
Thanks. I think it's the second one that I needed. You rock ! deeptrivia ( talk) 03:12, 4 April 2006 (UTC)
I am making a three sided pyramid out of three boards. They will be triangular and the edges will be mitred. I need a formula to calculate the angle of the mitres [based on number of sides (examp.7), angle of slope,length of base...etc.]. If possible, it would be nice to be able to put it on a spread sheet.
Can you help?
--- 70.50.197.126
I believe the answer will depend on the height of the pyramids. For example, with a triangular base, there are 180° inside the base. That makes 180°/3 or 60° between the sides. In the case of an infinitely tall pyramid with a 3-sided base, there would therefore be a dihedral angle of 60°. In the case of a pyramid of zero height, the dihedral angle is 0° (or 180°). Any height in between would have dihedral angles somewhere between 60° and 180°. Do you by any chance want to always use equilateral triangles ? If so, this will give a specific height for each pyramid.
In the case of a equilateral triangle base pyramid with equilateral triangles on the sides, as well, the dihedral angle is 70.53°, and the miter cut angle is (180°-70.53°)/2 = 109.47°/2 = 54.735°. In the case of a square base pyramid with equilateral triangles on the sides, the dihedral angle is 109.47° and the miter cut angle is (180°-109.47°)/2 = 70.53°/2 = 35.265°. In the case of a regular pentagon base pyramid with equilateral triangles on the sides, the dihedral angle is 138.19° and the miter cut angle is (180°-138.19°)/2 = 41.81°/2 = 20.905°. If a regular hexagon is used as a base, then the equilateral triangles would form a flat surface, not a pyramid. A regular heptagon or higher number of sides, used as a base, with equilateral triangles, would have gaps, and not form a pyramid at all. Note that the miter cut angles between the sides and base have not been discussed here. StuRat 02:42, 5 April 2006 (UTC)
To be more specific, the base could have from three sides to eight or nine sides and tapering to a point at the top. The height dosn't matter, it could be from two inches to two km. and same with the base. I'm looking for a formula wherby entering the variables (height, width, number of sides) I can calculate the angle at which to cut the mitres. Thanks --- 74.12.9.227
Thanks, it helps alot. --- 70.50.197.146
Thanks for the update! --- 74.12.2.9
Here's a graphics/geometry question, although fundamentally mathematical.. What's the best way of determining the control points of a cubic Bezier, so that is approximates the curve of a different Bezier? From searching, I've found there's no exact solution. But what kind of approximation is used? -- 130.237.205.132 17:47, 3 April 2006 (UTC)
The article on adjoint functors mentions that the diagonal functor is the left-adjoint of the product functor (this works for any limit), which gives the categorical product of two objects. This seems fishy to me. The categorical product is defined in terms of its univeral property. Thus, it is determined only up to canonical isomorphism. Thus I can't define a a functor here, since I don't have a unique choice of object. So I think this is only a pseudofunctor, not a full-fledged functor. Now, Mac Lane lists these guys as adjoint functors as well, and he makes no mention of pseudofunctors, so my question is, am I totally wrong about this? What's the deal? - lethe talk + 05:20, 4 April 2006 (UTC)
4 digit palindrome number two more than a perfect square
What would the mathematical approach to the problem be? :--) JackofOz 12:41, 5 April 2006 (UTC)
x | (1st digit = 4th digit) in x^2+2 | 4th digit in x^2 | 2nd digit in x | candidates |
32-44 | 1 | 9 | 3,7 | 33,37,43 |
45-54 | 2 | 0 | 0 | 50 |
55-63 | 3 | 1 | 1,9 | 59,61 |
64-70 | 4 | 2 | \ | \ |
71-77 | 5 | 3 | \ | \ |
78-83 | 6 | 4 | 2,8 | 78,82 |
84-89 | 7 | 5 | 5 | 85 |
90-94 | 8 | 6 | 4,6 | 94 |
95-99 | 9 | 7 | \ | \ |
what's up
Help, I posted a question about house numbering here 9 days ago, and now it and its possible answer have glided off the top with now way to retrive them! No link to go back one page of answers! If you see them send it to (email excluded) as who knows, I might not even get back to see the answer to this in time!
Try using a calculator, like the one built in to your computer. StuRat 08:49, 5 April 2006 (UTC)
* * * * * * * * * * * * * 1 2 4 4 2 0 * * * * * * * * * * * * *
Tell me the religious and mathematical significance of the Golden Ratio.
The Golden Ratio is the relationship between the width and length of a rectangle which is most appealing to the eye. It is used constantly in furniture design and different aspects of architecture. The ratio is, W=L×.618. --- 74.12.9.227
Consider a block design : such that the number of points equals the number of blocks : it is thus by definition a symmetric block design.
How can I prove that teh number of points v satisfies with the so-called order of the design
It's really only a subtlety I can't figure out. I know I should consider the equation
and substitute
I would get the result by demanding the discriminant of the resulting quadratic equation in being strictly greater than zero, but not in the exceptional case that the discriminant is exactly zero.
Any suggestions in avoiding this problem would be greatly appreciated.
Consider the number 1983. For 1983 foo = 1+9+8+3 = 21
But is there a special name for summing each individual digit, and if so what is it?
The most obvious thing is that multiples of 3 always sum to a multiple of 3, but you knew that anyway. I think there is a similar effect for 9, (3*3) but not 6.
The last two digits of multiples of 4 are always a multiple of 4, (and there are probably others) but you can answer my original question. — Dunc| ☺ 20:45, 5 April 2006 (UTC)
What is expansion by minors?
Thank you very much for the speedy response! :)
WHAT IS MEASURE OF DISPERSION?
a) A spherical snowball is melting in such a way that its volume is decreasing at a rate of 1cm3/min. At what rate is the diameter decreasing when the diameter is 10cm?. —This unsigned comment was added by 218.111.184.204 ( talk • contribs) .
To solve the equation of
for x, you would take each side the power of zero, right? So you would get
and since any number to the 0 power is 1, x=1.
So,
where y is any number.
Obviously, someone could use this to prove any number is equal to any other number.
Which leads to my final question: What are the restrictions of the transitive property? Does it state when you can't use it to argue certain things (such as the simple -1=1 using square roots proof)? Have the 'rules', if you will, of the transitive property, been agreed upon? 65.31.80.100 12:01, 7 April 2006 (UTC)
65.31.80.100 12:01, 7 April 2006 (UTC)
Well, I am sure this has to be simple, but my mind is all messed up right now. Suppose you have two curves, C1 defined by points (x1i,y1i,z1i) i= 1 to N1, and C2 defined by points (x2j,y2j,z2j) j = 1 to N2. How can I put the curve C2 at the end of C1 to get a smooth curve C3 with N1+N2 points. I have at my disposal a function that can numerically calculate the components of tangent, normal and binormal vectors at all these points (returning three arrays, each of size 3xN.) I guess the values of these vectors at the last point of C1 and the first point of C2 should suffice to find out the required rotation matrix for all points onC2. Any help will be greatly appreciated. deeptrivia ( talk) 02:12, 7 April 2006 (UTC)
On a sphere, a loxodromic arc ("H") travels in a constant direction, whereas an orthodromic arc ("ΔÔ") constantly changes direction. If one defined the loxodromic azimuth as and the orthodromic as , at infinitesimality the arc lengths and azimuths respectively equate. Would the technically proper way to express the azimuthal equity be
Is there such a thing as a fourier transform of a hilbert space? -- HappyCamper 19:30, 7 April 2006 (UTC)
What do you mean? If you consider the space of analytic functions on and make it a hilbert space with the classical integral formula, the fourier transform is a unitary bijective operator. Evilbu 19:47, 7 April 2006 (UTC)
When you evaluate e2πi, you get 1. Therefore
ln e2πi = ln 1
2πi = 0
2 = 0/πi = 0
π = 0/2i = 0
i = 0/2π = 0
How can this be true?
M@$+
@
Ju ~
♠
20:59, 7 April 2006 (UTC)
never quite got how this worked, how would you do it for:
If you could show me how to do it step by step on these specific questions it would be very helpful, oh and show your work (: 21:20, 7 April 2006 (UTC)
The answer to
3) 757 / 14244
is 757/14244 because it is a fraction. Perhaps you are asking about how to turn a fraction into a floating point number. Ohanian 04:52, 8 April 2006 (UTC)
Hi,
I have for quite some time been trying to find a convincing proof that there are infinitely many solutions to a + b = c where c is any number. It seems possible that either a) this is a very axiomatic result which cannot actually be solved, or b) I am simply too stupid/ignorant to be able to locate the relevant proof. Since this is vital to some (hopefully) useful mathematical work I am undertaking (although I wouldn't dare call myself a competent mathematician) any help would be unbelievably appreciated.
Thanks in advance, lynton
What set are you looking for solutions in? If a,b, and c are valued in the set {0}, then there is a unique solution. If they are valued in the group {0,1}, then there are 2 solutions if c is 0 but only 1 solution (up to ordering) if c is 1. Even more pathologically, if you assume that a and b are valued in the negative integers and look for solutions among the positive integers, there is no solution at all. Thus you see that how many solutions there are depends on what space you look for solutions in. Let's assume that you're looking for integer solutions. For each integer n, the ordered pair (n,c–n) forms a unique solution. Furthermore, any solution is of this form. This is all the solutions, and there are infinitely many of them. - lethe talk + 00:09, 8 April 2006 (UTC)
That may be so, but it does not constitute a proof that there are an infinite number of solutions noting my use of the words 'any' number or indeed any mathematical set on which addition is defined. The reason this proof is so essential especially in a cryptographical sense, is that it allows us to establish with certainty that given a member of a set with certain properties, it is impossible to calculate the values of a and b from c. Can anyone think of such a proof? Thanks again.
KSmrq, actually I was intending this proof to be a model for a proof for finite permutation groups, which are, i know, finite. However, all i wanted is a proof that covered say real numbers, and I'm pretty sure that it would go something like:
Set a to half of c and b to half of c. Then, add and take a number to each, until a and b reach their upper and lower limit. However, since you can always add and take a number to a and b, it is impossible for a and b to reach their upper and lower limits, and thus no such limits exist. Vice versa works also, with decrementing a and b incrementing. Therefore a and b have no upper or lower limits, rendering them infinite.
I know the way I have expressed this may not please you 'professional' types out there, but considering that you failed to produce even a rudimentary attempt, and instead stated the *blatantly* obvious, then proceeded to belittle someone, I'd say that any attempt is better than your pathetic contribution. I don't know what rock you come from under, but you mustn't be very proud of it, because you seem to be getting your self-esteem from the internet, of all places. Either help or crawl back home.
Yes, that tirade wasn't in any way pointed at your post, which i only just read enough to comprehend that it was exactly what I wanted in the first place (i read the bits about the more restricted cases and just assumed that the post was going to go on and say exactly what KSmrq did say) and I convey my greatest thanks for it. I think that what KSmrq said was based solely on miscommunication, but even if what i said was dead wrong, I really do not appreciate the insult. Incidentally, would you accept my proof as valid?
Thanks a lot, greatly appreciated.
how can i improve my mathematics? your help might save my life! thx
3 and -3
Thankyou
3 + -3 = 0. - lethe talk + 18:08, 8 April 2006 (UTC)
How about the lowly quadratic (x-3)(x+3)=0? Am I missing something here? —The preceding unsigned comment was added by 84.234.167.166 ( talk • contribs) .
People from Britannica randomly add these articles to create anarchy in wikipedia...
What is the smallest possible measurement of time? 204.112.201.7 20:02, 8 April 2006 (UTC)
If
is the pth symmetric power of an n-dimensional vector space, and
is the exterior power or alternating power, do I have a canonical isomorphism
I think I ought to, but I'm having a hard time writing down such an isomorphism. - lethe talk + 20:14, 8 April 2006 (UTC)
Is considering decision problems in lieu of computational problems sound? The relevant articles use an argument that deciding if x is in language L is equivalent to computing the characteristic function and checking if output is 1. But the characteristic function is defined in terms of the decision problem.
I can't seem to understand why this is sound? Further, if a characteristic function doesn't exist without resorting to using the decision problem, what good is it in showing their equivalence?
Do I understand the proof correctly?
I apologizes for the computer language python, but is the fundamental algorithm for calculating log2(x) aka logarithm base 2 correct?
The numeric value of the binary logarithm of a positive real number can easily be calculated using only the addition, subtraction, multiplication and division arithmetic operators. Here is a sourcecode in python which produces the value.
#!/usr/bin/python from __future__ import division def log2(X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * 2 while X >= 2: integer_value = integer_value + 1 X = X / 2 decfrac = 0.0 partial = 0.5 X=X*X while partial > epsilon: if X >= 2: decfrac = decfrac + partial X = X / 2 partial = partial / 2 X=X*X return (integer_value + decfrac) if __name__ == '__main__': value = 4.5 print " X =",value print "LOG2(X) =",log2(value) # Sample output # # $ python log2.py # X = 4.5 # LOG2(X) = 2.16992500144 #
#!/usr/bin/python from __future__ import division def log3(X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * 3 while X >= 3: integer_value = integer_value + 1 X = X / 3 decfrac = 0.0 partial = 1/3.0 X=X*X*X while partial > epsilon: while X >= 3: decfrac = decfrac + partial X = X / 3 partial = partial / 3 X=X*X*X return (integer_value + decfrac) def log4(X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * 4 while X >= 4: integer_value = integer_value + 1 X = X / 4 decfrac = 0.0 partial = 1/4.0 X=X*X*X*X while partial > epsilon: while X >= 4: decfrac = decfrac + partial X = X / 4 partial = partial / 4 X=X*X*X*X return (integer_value + decfrac) if __name__ == '__main__': value = 4.5 print " X =",value print "LOG3(X) =",log3(value) print "LOG4(X) =",log4(value) # $ python log34.py # X = 4.5 # LOG3(X) = 1.36907024643 # LOG4(X) = 1.08496250072
Ohanian 11:21, 10 April 2006 (UTC)
So, presumably we can generalise to a function giving logN(X):
#!/usr/bin/python from __future__ import division def log(N,X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * N while X >= N: integer_value = integer_value + 1 X = X / N decfrac = 0.0 partial = 1/float(N) X=X**N while partial > epsilon: while X >= N: decfrac = decfrac + partial X = X / N partial = partial / N X=X**N return (integer_value + decfrac)
though as I don't do Python my syntax may be wrong in places ... Would it work for non-integer N? -- Bth 11:49, 10 April 2006 (UTC)
#!/usr/bin/python from __future__ import division def log(N,X): epsilon = 0.000000000001 integer_value=0 while X < 1: integer_value = integer_value - 1 X = X * N while X >= N: integer_value = integer_value + 1 X = X / N decfrac = 0.0 partial = 0.5 X=X*X while partial > epsilon: while X >= N: decfrac = decfrac + partial X = X / N partial = partial / 2 X=X*X return (integer_value + decfrac) if __name__ == '__main__': value = 45.7 print " X =",value print "LOG6(X) =",log(6,value) print " LN(X) =",log(2.718281828,value) # SAMPLE OUTPUT # $ python log.py # X = 45.7 # LOG6(X) = 2.13315367578 # LN(X) = 3.82209829854
I checked the article but it simply said it was derived from the Pythagorean theorem. Don't worry its not homework I'm just curious...
(x1,y1) 1 /\ . . | . . | . . (y1-y0) . _ | 0 . . . . . . .|. \/ <----(x1-x0)----> (x0,y0)
Thanks Bth...but isn't that the same as sqauring the two parts of the slope?
i.e if the slope is 7 over nine, the sum of those squares would be the same thing right?
No, I mean that the 2 components are the same in distance (as you said) so if you sqaured the two components of slope and added them, then took the root of that, would not that be the same thing?
Oh yeah, didn't think of it that way...anyway thanks for the help.
ok, with working out the range, range=highest - lowest, does the lowest include zero.
e.g. if the numbers are 1, 5, 7, 8, 0, 10
would the range be 10-1 = 9
or
would it be 10-0 = 0
i really dont understand and usually i'm pretty good at this whole maths thing.
thanks, skye
Thanks heaps, got lab report due tomoz and was stressin heaps, thanks sooooooooo much, cya, skye
Hi I am trying unsuccessfully to make permutations for a golf trip for 20 players. Over 4 rounds, played in groups of 4, the players should rotate so that none of them plays together more than once. I am sure that there is an easy answer, but we can't find it. Please help. Thank you
abcd|efgh|ijkl|mnop|qrst arol|ebsp|ifct|mjgd|qnkh angt|erkd|iboh|mfsl|qjcp ajsh|encl|irgp|mbkt|qfod afkp|ejot|insd|mrch|qbgl
When talking about a limit, equation, solution, or stuff like that, what is the different between using undefined, DNE, and no solution? And when should I use which one? —Preceding unsigned comment added by 72.59.31.118 ( talk • contribs)
Will you explain to me how to do this problem? I'm doing a makeup assignment from being gone, so I missed the lesson. Also, it can help me do the others once I know how to figure these out. Ok here's the problem
2 over (x-2) squared = 1-1 over x-2
Your help would be greatly appreciated. Also, sorry for the equation form, I don't know how to do all of the math symbols on the computer! Thanks alot! Kirsten (aka 65.101.68.120)
I have a number--> 1.4190792748769801e+26 --> and i want to know what the e+26 part of it means. Do i move the decimal 26 places? help please
Hi,
I have a set of parametric eqations defined as
where
and I have to find the cartesian equation in terms of y. So far I've got
but I cant get any further. I've got a feeling that
comes into it somewhere. Can anyone help?
Whoops - must remember to sign Anand 14:11, 11 April 2006 (UTC)
Quick question for ya'll. I'm an engineering student, and have taken all the required math courses (calc up to diff eq). I'm going to be solving PDEs until I die, I know that already. But what's a "fun" math course to take? Something theoretical? Analysis? Probability? I'd like a broad knowledge of some basic stuff. Even though it does not pertain to my major, I plan on taking relativity next year for some kicks. Thanks in advance! Isopropyl 14:32, 11 April 2006 (UTC)
Should I be able to understand intro level combinatorics or toplogy with my math background? I've only had three semesters of calculus. Isopropyl 20:16, 11 April 2006 (UTC)
I have another idea for a fun math class for you. Differential geometry. Often, a first course in differential geometry is simply a continuation of stuff you learned in vector calculus, the differential geometry of curves and surfaces in R3. Thus it fits your prerequisites perfectly. It's a nice springboard into Riemannian geometry, should you decide to take that at a later date, or general relativity. And you'll learn the Gauss-Bonnet theorem, which may whet your appetite for a topology course. - lethe talk + 21:14, 11 April 2006 (UTC)
I would like to thank you all for your recommendations. However, it seems that I need to take Analysis 1 at my school before I can take anything that's not engineering-oriented applied math (probablity for example). I'll look into your suggestions at a later date. Thanks though! Isopropyl 22:01, 11 April 2006 (UTC)
What is the best way to approach something like y = -4sin (2x + π/4)+ 5? No it's not for homework, any example would be great (anything with a reflection, vertical shift, horizontal shift and all of that together so it's approaching the highest degree of difficulty). Also I was wondering how do you know whether you should graph the x-axis in radians or degrees? Thanks
C-c-c-c 21:22, 11 April 2006 (UTC)
Thanks a lot!
C-c-c-c
01:52, 12 April 2006 (UTC)
I know, but cannot prove, that two consecutive integers are always going to be relatively prime. Does anybody have a proof?
Also, my teacher gave us the following puzzle:
12 1112 3112 211213
And asked us to find the next row (which is 312213). He then said that these triangles can start with any numbers (except 0), and asked us if they will all eventually repeat, or whether some will continue to grow. (A side problem which I have already solved, what is the shortest set of starting numbers that will repeat immediately).
12 34 1112 1314 3112 211314 211213 31121314 312213 41122314 212223 31221324 114213 21322314 31121314 etc. 41122314 31221324 21322314 21322314 etc.
Whereas the Look-and-say sequence goes as follows:
1 11 21 1211 111221 312211 13112221 1113213211 etc.
My question is now, for any starting numbers, will the sequence eventually fall into a loop as shown above for 12 and 34?
tell each gcf you would use to simplify the fractions.
Is there an easier practical illustration of the common terms we use in Electromagnetic Theory like Gradient,Curl,Divergence?
what is the simple low to calculate the distance between the two points on the earth by using geographic Coordinate
Say there is an election in which 100 people vote, and the result is split 50-50. If it was noticed that 20 of the people in favor of the measure owned cats, while 5 of the people against it owned cats, how would I determine if cat ownership was statistically likely to have influenced the outcome of the vote?
Say the vote is run again, with 100 different people, this time including 30 cat owners. Assuming cat ownership is significant, and that there are no other influencing factors, how would I determine the odds of the majority being in favor? -- Serie 21:46, 12 April 2006 (UTC)
Are there any tricks to remembering the unit circle? C-c-c-c 00:34, 13 April 2006 (UTC)
When trying to remember specific cos, tan, sin, sec, csc, and cot values for certain angles (30, 45, 60, 90, 135...etc) C-c-c-c 01:08, 13 April 2006 (UTC)
I'm doing some computer programming and I need some way to compute the digits of an irrational number (specifically, a square root or something like pi or e anything will do). But I need more digits than C or VB can provide with a regular classification, which I think is in the double, 15 digits?? (also I need the program to do it itself, no cheating off the web to get the digits). Is there an easy way without any severe progamming to calculate digits?
I was thinking the only way would be to program a new function that does multiplication and adding longhand, storing each subsequent number from a series like Ramanujan's ( History_of_numerical_approximations_of_π) and adding them longhand, digit by digit, carrying the 10, 100, 1000 etc.
I found this for pi: Bailey-Borwein-Plouffe_formula but I don't think it is applicable. As far as I can tell, the method to compute 16^(n-k) mod(8k+1) described in Exponentiation by squaring still requires that my data will be able to store 16^(n-k). And what about that second term? I don't know enough (or have forgotten enough) calculus to determine what the infitine sum of 1/(16*(8k+1)) from k = n+1 to infinity will equal...but it probably won't affect the rounding of the integer which I assume is the nth digit?
any ideas would be appreciated.
Thanks, - Snpoj 03:42, 13 April 2006 (UTC)
? # timer = 1 (on) ? \p 2000 realprecision = 2003 significant digits (2000 digits displayed) ? sqrt(Pi) time = 74 ms. %5 = 1.772453850905516027298167483341145182797549456122387128213807789852911284591032181374950656738544665416226 823624282570666236152865724422602525093709602787068462037698653105122849925173028950826228932095379267962800174 639015351479720516700190185234018585446974494912640313921775525906216405419332500906398407613733477475153433667 989789365851836408795451165161738760059067393431791332809854846248184902054654852195613251561647467515042738761 056107996127107210060372044483672365296613708094323498831668424213845709609120420427785778068694766570005218305 685125413396636944654181510716693883321942929357062268865224420542149948049920756486398874838505930640218214029 285811233064978945203621149078962287389403245978198513134871266512506293260044656382109675026812496930595420461 560761952217391525070207792758099054332900662223067614469661248188743069978835205061464443854185307973574257179 185635959749959952263849242203889103966406447293972841345043002140564233433039261756134176336320017037654163476 320669276541812835762490326904508485320134192435989730871193799482938730111262561658818884785977875963761363218 634246546641333954355703201522654193952186030497310513829498439659165614245955421226615102478536098095510395600 789402188099613382854025016800745802729119366425192820510001936350073914643295493433951928853735459200563766502 880540575532123189009126322819150914980836695624483100852221923973646324842863261145766932425371577377894414090 544573595351225626391080239236909732127905807617134603914574791879794124850218445145811341888880413220955332184 646709727491028565262707845453262227848800982385836300754950954764062377083388357225436621567481327668384244972 420874516161833205077991480184666814236693651902845463857614827857037774388376297479982737705431583682410998683 228503805526355369722293133805264428410372312043967004307612454138311792278275363715598398376884537027842985707 0905112238405367790133854145853162080730431380697399874366931660138170792720560419548828580630931116362970478678140270
PARI/GP computer algebra system -- GangofOne 06:23, 13 April 2006 (UTC)
I know that Period = 2π/|b|
where b is the horizontal stretch or compression. So for example, 2SinΘ would be 2π/1 = 2π or 360 degrees. Sin2Θ would be 2π/2 = π or 180 degrees.
Now, if I switch this formula around I can have |b| = 2π/period. That means that b must always be positive, something I'm not quite sure of. Now that I think about it I don't think we've ever had a negative b in our tranformation graphing. Does it not exist or is that too complicated for my level (high school)? Thanks.
C-c-c-c 04:41, 13 April 2006 (UTC)
I came up with a proof of the angle bisector theorem (I'm not sure if its' original or not, but I haven't encountered it anywhere else). I'm trying to see if anybody will publish it, but I can't find any appropriate journals. I know that Wikipedia has an article on mathematical journals, and the two big English ones I see are Annals of Mathematics and the Journal of the American Mathematical Society, but the papers in these journals are extraordinarily complex; they're dozens of pages long, use computers, cite references, etc.
Could anyone suggest a mathematics journals that would publish such a simple, geometric proof? Thanks
-- JianLi 18:43, 13 April 2006 (UTC)
Just curious, what's the biggest discovery in the field of mathematics in recent history (excluding prime numbers, etc.)?
OR ?
I believe it is the second, but my friend disagrees. -
Mystaker1
03:08, 16 April 2006 (UTC)
Also, I'm not sure if I understand infinitesimals. Can you tell me whether this equation is solved correctly or not? - Mystaker1 03:31, 16 April 2006 (UTC)
We were doing some stuff on Hilbert matrices in applied maths (really just MATLAB practice) and I was playing around and discovered that . Are they exactly equal? And could anyone give me a hint on proving it? (Just for fun - this isn't homework or anything.) -- 대조 | Talk 11:54, 16 April 2006 (UTC)
Dear Math Ref. desk: I have a really simple question that is really dumb but I have been struggling with it. It is a SAT II Math IC question. I am not posting a homework. Thank you for your help.
5. What are all values of x for which (4−x)2 ≥ (x−2)
The given answer is (C) and the difficulty level is 3. I would like to have some procedure also. I tried to solve it myself but I think I am missing something.
-- Kushal [e-mail address not entered] The preceeding question was added by Kushal one Kushal one 18:11, 16 April 2006 (UTC). Please visit my talk page to resolve any suspicion of trolling by me. I previously used to make (very few) comments under the name "My IP address is not permanent." and variants. Thank you for taking yout time once again.
Correction: Thank you, KSmrq. The parentheses were clearly wrongly put. Signs of a clumsy student... Please read the above question as KSmrq put it. I assure you, however, I did not make that mistake on paper. Thank you I will see your guidance and try to do the problem again. I still think there is something I am missing... Kushal One
STILL HAVE TROUBLE
prove that if N is a normal subgroup of G and H is any complex of G then NH=HN
I read some where that given a long list of multi-digit (random?) numbers, the number 1 will occur as the first digit far more often than 10% (I think it was somewher around 30%...). Can anyone tell me more about this? SigmaEpsilon → ΣΕ 21:24, 16 April 2006 (UTC)
Need assistance with this question, not clear on how to put the monthly summary together to get the total material payments for January. Please email me at e-mail removed; see the note at the top of the page. Many thanks
The Denver Corporation has forecast the following sales for the first seven months of the year:
January $9,000 May $10,000 February 12,000 June 16,000 March 14,000 April 20,000 July 18,000 Monthly material purchases are set equal to 30 percent of forecasted sales for the next month. Of the total material costs, 40 percent are paid in the month of purchase and 60 percent in the following month. Labor costs will run $4,000 per month, and fixed overhead is $2,000 per month. Interest payments on the debt will be $3,000 for both March and June. Finally, the Denver sales force will receive a 1.5 percent commission on total sales for the first six months of the year, to be paid on June 30.
Prepare a monthly summary of cash payments for the six-month period from January through June. (Note: Compute prior December purchases to help get total material payments for January.)
This has nothing to do with mathematics.
Ohanian
04:49, 17 April 2006 (UTC)
I am submitting this with all respect to the respected RD sirs and madams. Please take it with a pinch of salt.
Dear ‘Aklepard’:
I am submitting you my interpretation of the answer. Please use your own mind to see through the problem as my answer may have flaws. Furthermore, please do not forget to check back on the reference desk for other (better) answers by users and administrators that are more informed.
Month Forecasted sales Monthly material payment payment same month Payment next month Labor Fixed overhead Interest payment Commission
December -- 3000 1200 -- 4000 2000 0 0
January 10000 3600 1440 1800 4000 2000 0 0
February 12000 4200 1680 2160 4000 2000 0 0
March 14000 6000 2440 2520 4000 2000 3000 0
April 20000 3000 1200 3600 4000 2000 0 0
May 10000 4800 1920 1800 4000 2000 3000 0
June 16000 5400 2160 2880 4000 2000 0 3000
July 18000 these details here are not required for the present calculation..........................................................................................................................................
[NB: ‘--’‘means ‘cannot calculate’ and ‘0’ means no ‘payment’ necessary.]
Add columns ‘payment same month’ and ‘Payment next month’ to get ‘total material payments’ for that month. FYI, the January figure is USD 1440 +USD 1800 =USD 3240
To get total value of monthly value of cash payments, add columns 3, 4, 5, 6, 7, 8, and 9.
If you are still confused, post your confusion on the reference desk.
Yours truly,
Kushal Hada [contact info removed but ca be found on my talk page.]
PS It is not considered a good idea to post your e-mail address on the RD. I hope you understand.
PPS I apologize in advance if I offended you in any way.
-- Kushal one 00:25, 18 April 2006 (UTC)
So there is an article about Fibonacci Poems at the NYTimes [2]. They introduce the concept of Fibonacci numbers by saying, "Readers of the blockbuster best-selling "Da Vinci Code," of course, may recognize the Fibonacci sequence as the key to one of the first clues left for the novel's hero and heroine" which just shows you how idiotically innumerate the general public is. But anyway, that's not my point. I have a question about this:
Let P be a set of points in general position in the plane. Amen. The last line, said Mr. Venkatasubramanian, is an inside joke in geometry.
Can anybody explain this joke to me? I googled it, and found it again at [3], but with no explanation. JianLi 01:41, 17 April 2006 (UTC)
Can anyone, please, tell me the method of how to resolve these? Thanks in advance.
Afraid the link won`t work therefore it is named after this man
http://img133.imageshack.us/my.php?image=6b7ld.gif
Please Can You tell me the name of this Mathematical Function?
It`s Similar to a wave it`s pink and black.
Which article should I look to search for mathematical formulas in non-euclidian universes, that is not a infinite plane.
More specific, i want to be able to calculate things like shorter distance between two points, pythagorean theorem and point of intersection of two line segments, but all of those in the surface of a sphere.
Thanks -- Alexandre Van de Sande 20:03, 17 April 2006 (UTC)
I have a mac and a pc, a big interest in mathematics and some basic experience on some programming languages. I want to program an application that map networks, wich basically draws sets of lines among a growing point set according to some basic rules.
which program do you recommend, something with a low learning curve. Thanks
please can someone please give me the stepwise linear regression equation.
I'm looking for the equation for the circumphrance of a certain longitude; for example, the circumphrance of a smaller circle that's 45 degrees above the exact middle of a spere. Tell me if I need to be clearer than that. Jonathan talk 19:31, 18 April 2006 (UTC)
Are you sure about that? I tried that formula and kept getting negative numbers. (For instance, 2 times pi times 10 times the cosine of 10 equals: -52.7204.) Jonathan talk 00:29, 19 April 2006 (UTC)
I'm trying to find out the function to draw the terminator line on a plate carrée projection of Earth's surface. Thing is, I have a map with the continents and everything, and I want to generate the terminator line of the given period of the year and use it to create a shadow layer over the map. The time of the day part I can figure by myself. Oh, and it doesn't have to be utterly precise, just good enough.
Anyway, this proved to be a tricker than I thought. As you probably know, Earth axis has a tilt (23.45°), so the terminator isn't a simple meridian line, but a curve, and depending of the time of the year this curve changes. Can anyone help? ☢ Ҡi∊ff⌇ ↯ 20:46, 18 April 2006 (UTC)
A circle is drawn. Two points are marked on its sides. We join the 2 points. Thus, we divide the circle into two parts. Into how many parts can the circle be divided for "n" no. of points?. Find the formula
I worked it out on paper and it looks to me like your formula is:
Because when I used 2 points I got 2 section; 3 points = 4 sections; 4 points = 8 sections; 5 points = 16 sections... Jonathan talk 21:13, 18 April 2006 (UTC)
1 | = 1 = 1 1 1 | = 1+1 = 2 1 2 1 | = 1+2+1 = 4 1 3 3 1 | = 1+3+3+1 = 8 1 4 6 4 1 | = 1+4+6+4+1 = 16 1| 5 10 10 5 1 | = 5+10+10+5+1 = 31 1 6| 15 20 15 6 1 | = 15+20+15+6+1 = 57 1 7 21| 35 35 21 7 1 | = 35+35+21+7+1 = 99 1 8 28 56| 70 56 28 8 1 | = 70+56+28+8+1 = 163
If we add all the numbers on the right hand side of the line per row, we get 1, 2, 4, 8, 16, 31, 57, 99, 163. -- Alexs letterbox 23:06, 18 April 2006 (UTC)
I'm not quite sure how to ask this, so bear with me. I'm looking for a field of mathematics/analysis that I've never heard of or run across, that I can't think of a name for, but that I'm certain must exist somewhere. I'm trying to solve a problem that involves taking a set of objects (one-digit numbers), arranging combinations of them within a structure, and finding a particular combination that satisfies certain criteria. It would have to be able to deal with a situation where 1)There are too many possibilities to try every one (unlike Anagrams), and 2)There's no obvious series of deductions that solves it one piece at a time (unlike Sudoku). A bit like a Magic Square, really, though apparently there are formulas that solve most of those. Any ideas? Black Carrot 21:07, 18 April 2006 (UTC)
Hi, I have a Java program to do that I just can't crack.
These are the instructions given:
Create a class called Sentence with the methods as listed below. This class has one String field called aSentence that holds several words separated by spaces. Your client class used to test these methods called RunSentence should use file input. Use the file in the pickup folder called “sentence.txt”
//create a constructor method, a mutator method and an accessor method
//purpose: the method should return the number of words in the sentence
public int numWords( )
So, the question asks for the number of words. I thought about this and assumed: number of words is number of spaces plus 1. For example "This is a sentence", has three spaces, and 4 words, and so on ( I don't think we have to worry about two spaces in between, just started strings not so long ago).
aSentence is my string here, n keeps track of the spaces and I've set n to 1, because if anything is written there will always be something (ie. one word). I have no syntax erros but the debugger isn't working for me so I have no idea what's wrong with it. Int index gives me an integer value of how long the string is. I've set position to 0 so that it counts from the first index. The repition statement is position == index, so once I get position to equal index, I'm at the very end of the string.
In the first part of the for loop, position is 0, and it checks for where " " is found. So then position becomes 4, and it adds one to n because it found a space, therefore a word. Next it does it pretty much the same thing, but adds one to the that 4, which then becomes 5. After it does aSentence.indexOf ( " ", 5) it becomes 7, where 7 is the next space. Then it adds 1 to that 7 and starts again. I have it add this one to stop it counting the space twice, if that makes any sense to anyone.
If anyone has any idea about any of this, please help thanks.
public int numWords() { int n = 1; //counts number of spaces int index = aSentence.length()-1; for ( int position = 0; position == index; position = position + 1) { position = (aSentence.indexOf ( " ", position)); if ( position != -1) { n = n +1; } position= (aSentence.indexOf( " ", position+1)); if ( position != -1) { n = n +1; } } return n;
}
C-c-c-c 06:05, 19 April 2006 (UTC)
I see several problems with this code. For one, you shouldn't change your position variable inside a block of code whose termination rests on position reaching the length. For example, it looks like if you feed that code a string with no spaces, it will set position to -1 on the first pass, and never terminate. If all you want to do is count the number of spaces, then why don't you just do
n=0; for (int i=0;aSentence.length()-1;i++) if (aSentence[i]==' ') n++;
- lethe talk + 07:39, 19 April 2006 (UTC)
public class StringUtilities { // name arbitrary; would be combined with other such functions public static int countWords(String s) { int ret=0; boolean wordstart=true; for(int i=0;i<s.length();++i) { if(s.charAt(i)==' ') wordstart=true; else if(wordstart) {++ret; wordstart=false;} } return ret; } }
This handles multiple spaces properly, as well as spaces at the beginning or end of the string. It's still a very naïve definition of a "word" counter, though. -- Tardis 19:21, 19 April 2006 (UTC)
WordCountableString extends String
or so. Certainly some strings cannot be said to contain words, for instance "+!@#($!*(%@@^"
or "42"
, depending on your definition of "word". But because it's entirely fair to say that such strings have 0 words, the function that gives the number of words in is well-defined for any , given a suitable unambiguous definition of "words" and boundaries between them. So what we'd really want is some sort of
aspect-oriented programming approach where we embued all Strings with the capacity to report on their own word counts.String
functions on a "fake subclass") would seem to naturally extend to having a FirstLetterMayBeUppercaseString
class which supports the boolean beginsWithUpper()
function. And then why not (supposing
multiple inheritance, while we're invalidly subclassing String
anyway) have WordCountableStringPerhapsWithInitialUppercaseLetter
that extends both of these? I don't think that the notion of defining arbitrary functions on Strings is possible to fit into the usual OOP model. Thus my simple suggestion of a utility function, since that's what's being requested (a function).WordCountingReader extends FilterReader
with the obvious semantics. Then you're adding behavior to a well-defined object, rather than simply defining a function of a well-defined object. Seems like a better fit to me. (Sorry this is so long, and again if I'm misunderstanding you!) --
Tardis
21:54, 19 April 2006 (UTC)solve for x and y:
m/x +n/y = a p/x +q/y = 0
solve for x and y:
m/x +n/y = a p/x +q/y = 0
becomes
solve for U and V:
mU + nV = a pU + qV = 0
x = 1/U and y = 1/V
very easy. Ohanian 02:22, 20 April 2006 (UTC)
Numerous papers (such as this) explaining Rand index (for which there's no Wikipedia article) use a bracket nomenclature similar to that of column vectors but with normal parentheses () rather than square brackets []. I can't understand what this bracket nomenclature is referring to. The worked example is:
Can anyone explain to me how this answer is achieved? I'd be most grateful!! └ UkPaolo/ talk┐ 19:52, 19 April 2006 (UTC)
A bridge needs to be suspended over a river. The bridge will be one mile in length. If a (one mile + 2 feet) cable is used as the suspension cable, what is the largest type of animal that will be able to cross under the suspension cable at the mid-point of the bridge?
Choices:
How do I solve this?
Thank you for your help.
-- User:Archie44 10:20, 20 April 2006 (UTC)
I would say it couldn't support any weight, because to use a 5282 foot cable to span a 5280 foot gap, you would need to exert an enormous amount of tension to prevent it from sagging more in the middle. This tension would be so high that any materials we have would fail under such a stress. StuRat 07:28, 21 April 2006 (UTC)
I'm not sure if this comes under maths or science, but I'll try it here: sand is falling onto a conveyor belt at a rate of 0.2kg/s. The conveyor belt is moving at a rate of 3m/s. There are four questions:
These are fairly straightforward. Since force is , the answer to the first part is clearly 0.6N. For the second, we see that 0.6N is applied over 3m every second, so the rate of work is 1.8W. For the third, there's 0.2kg of new mass every second, which will add of kinetic energy every second, i.e. 0.9W. I can't for the life of me explain 4, though---where the extra energy every second is going, if not being stored as kinetic energy. I've considered examining the centres-of-mass (consider the 0.2kg being dropped at one point - it takes 0.9J of work to spread that out over 3m, and another 0.9J to accelerate it to 3m/s), but this falls down because you get the spreading for "free" (I think). This isn't homework. Any help definitely appreciated. -- 83.147.171.12 10:57, 20 April 2006 (UTC)
Do we have an article that covers how to factorize integers in polynomial time, or whether this is possible, or the repercussions on the entire computer security systems we use if this mathematical breakthrough happened, or if somebody is attempting to solve this problem?-- Sonjaaa 14:36, 20 April 2006 (UTC)
What is the logic behind the size of ID Card as 85.6 mm x 53.98 mm ? —Preceding unsigned comment added by 202.70.64.15 ( talk • contribs)
The ratio of the sides is related to the `golden mean', thought by the Greeks to be the most pleasing ratio of sides in a rectangle See http://goldennumber.net/creditcard.htm
A quick question regarding vectors and sets. Is the length of a vector written or , or can it be either? Which is most commonly used? What about a set , does that have size or (or either)? I'd be grateful if someone could clarify this for me! └ UkPaolo/ talk┐ 18:20, 20 April 2006 (UTC)
I have several computer programs that I installed on my computer - but every time I try to use these programs it say I have to have the CD in the drive before it will run. Is there a way to completely install these CD's and then point the program to the full install rather than the CD drive? Thanks for you help in advance Maria
Please can someone explain to a non-mathematician why prime numbers are needed to create keys for RSA cryptosystems. Wouldn't any sufficiently large number be o.k.?
Thanks for your help guys, I still don't think I understand. Probably because I stopped learning maths aged 14 (now 29). Please can you recommend a good primer on this? EmperorMoo 20:53, 21 April 2006 (UTC)
Thanks everyone, I think I'm going to have to read more maths background before I'm able to understand. EmperorMoo 12:48, 23 April 2006 (UTC)
O genius Wikipedians, I pray to thee to give a helping hand to a fellow bemused user. This is a homework question, I apologize - but I'm not asking for the answer (as it is given), but more so the best way about going about the question in order to get the answer. If possible pls put this into proper Maths syntax, and give me a link to how to write in maths syntax:
A person wishes to walk from (0,0) to (1,1) in the x-y plane in the shortest possible time. The nature of the ground is such that the max. speed of walking is given by "v=v0(1 + αy)" where v0 and α are constants. Show that the path taken is the integral between 0 and 1 of √(1 + (y′)2) / (v0(1 + αy)). The next bit of the question is "Show that the path taken should be an arc of a circle with centre on the line y = −1/α". Please give me a nudge in the right direction. All help is completely appreciated. -- Dangherous 13:31, 21 April 2006 (UTC)
I am having trouble with a specific problem from my statistics homework. I'd appreciate any help given.
Suppose you own a basketball team. Suppose also that in the NBA the average salary of players is $5,000,000. The lowest salary you can offer is $385,000. You plan to sign 15 players.
Construct a set of 15 data elements that have a mean of $5,000,000 spending the least amount of money possible.
Is there a formulaic way to solve such a problem? Or is the only way to fiddle around with various numbers? -- Impaciente 02:25, 22 April 2006 (UTC)
What does the "kis" particle mean in the names of the following geometric figures (and others)?
I've noticed that all the figures in question have triangular faces, but I don't understand what the number (tria, tetra etc) represents. -- 72.140.146.246 03:34, 22 April 2006 (UTC)
Thank you. This is exactly what I wanted to know. But what about "disdyakis"? -- 72.140.146.246 12:55, 22 April 2006 (UTC)
Thanks. I did some investigation, and found that the disdyakis dodecahedron can be formed from a rhombic dodecahedron by quartering each face and raising the center point (as tetrakis). It was the rhombic part that got me. -- 72.140.146.246 20:56, 24 April 2006 (UTC)
See http://en.wikipedia.org/wiki?title=Talk:Catalan_solid and http://en.wikipedia.org/wiki/Conway_polyhedron_notation
(No question.)
Try Poisson distribution. linas 00:28, 23 April 2006 (UTC)
A 20 kg box rests on a table. What is the weight of the box and the normal force acting on it? b) A 10 kg box is placed on top of the 20 kg box. Determine the normal force that the table exerts on the 20 kg box and the normal force that the 20 kg box exerts on the 10 kg box.
First I did: a)
W = mg W = 20(9.81) W = 196.2 N (DOWN)
ΣFy = ma
Since there is no movement in the vertical direction, Fy = 0
FN - FG = 0 FN = FG FN = 196.2 N (UP)
This part was easy, but my question concerns the second part. I did:
b)
ΣFy = ma
This equals zero again...and this where I'm unsure (FN2 = 10 kg object, FN1 20kg object)
FN2? + FN1 - FG = 0 FN1 = FG - FN2 FN1 = 9.91(20) - 9.81(10) FN1 = 98.1 N (UP)
And the second part of part b...
ΣF = ma FN - FG = 0 FN = FG FN = 10(9.81) FN = 98.1 N (UP)
I'm not sure about this, that's what I have up there so if anyone can point me in the correct direction or explain to me why I'm right (I think I am, but I am not sure, and I need to be sure of the concept) it would be greatly appreciated. Thanks
C-c-c-c
04:02, 23 April 2006 (UTC)
Right, I changed that. So, wait, have I done it right? I'm starting to think I haven't since I didn't include the FG for the 10kg box in the first part of question b. Instead should it be:
ΣFy = ma FN1 + FN2 - FG1 -FG2 = 0 FN1 = FG1 + FG2 - FN2 FN1 = 9.81(20) + 9.81(10) - 9.81(10) FN1 = 196.2N (UP)
This doesn't seem right either, since it's the same as up top.... Help, utterly confused! C-c-c-c 04:26, 23 April 2006 (UTC)
Isn't that what I have there? I have FN2 = 9.81(10) C-c-c-c 04:44, 23 April 2006 (UTC)
Yes, but you have FN1 + FN2 - FG1 - FG2 = 0. Why should the sum of those forces be zero if they are not all acting on the same object? — Keenan Pepper 04:53, 23 April 2006 (UTC)
But isn't that an entire system, can't you do it like that too? C-c-c-c 04:55, 23 April 2006 (UTC)
Oh, I didn't know you didn't include internal forces. Okay that makes sense, thank you so much for you taking the time to going back and forth and helping me, I appreciate it! Thanks a bunch again.
C-c-c-c
06:08, 23 April 2006 (UTC)
After explaining the process of determining the checksum of an ISBN, the ISBN article says, "Since 11 is a prime number, this scheme ensures that a single error (in the form of an altered digit or two transposed digits) can always be detected." How does 11's being prime affect its usefulness for checksumming? 139.55.22.138 19:54, 23 April 2006 (UTC)
How can I compute E[Max(X,Y)] (Mathematical Expectation)?! Armandeh 22:07, 23 April 2006 (UTC)
Does anyone know what the control sequence for Vinogradov's version of the big O notation is? The closest I can find is , but the right "<" should be cut off where the left one ends. Often found in books on analytic number theory. Mon4 00:16, 24 April 2006 (UTC)
Hello. I'm a beginning programmer. Two years ago, I tried to learn Visual C++ .NET. That was really, really hard. I wasn't able to do anything besides the tutorial in the book, so I quit. About four months ago, I picked up Liberty BASIC. I am able to do a lot and understand the language. I really enjoy it and am doing a lot of fun stuff. I wondered if anyone had any suggestions on other languages to try next or any suggestions about a good progression of languages for a learning programmer. Any stories about what you did, what you wish you did, or just simply any advice you have would be great. Thanks for your help. -- Think Fast 01:23, 24 April 2006 (UTC)
A lot depends on what you want to do. Different programing languages are better at different tasks. Do you want to write
In terms of your programming development getting some Object-oriented programming under your belt is a good idea. You might like to look at Slashdot where the pros and cons of different languages are endlessly debated. -- Salix alba ( talk) 10:12, 24 April 2006 (UTC)
Can you please explain how this formula was formulated?
(141.5/SG at 60degF)-131.5
this formual is used to calculate the API gravity of cude oil.
thanks
thank you Melchoir....... anyone has more??
O genius Wikipedians, I pray to thee to give a helping hand to a fellow bemused user. This is a homework question, I apologize - but I'm not asking for the answer (as it is given), but more so the best way about going about the question in order to get the answer. If possible pls put this into proper Maths syntax, and give me a link to how to write in maths syntax:
A person wishes to walk from (0,0) to (1,1) in the x-y plane in the shortest possible time. The nature of the ground is such that the max. speed of walking is given by "v=v0(1 + αy)" where v0 and α are constants. Show that the path taken is the integral between 0 and 1 of √(1 + (y′)2) / (v0(1 + αy)). The next bit of the question is "Show that the path taken should be an arc of a circle with centre on the line y = −1/α". Please give me a nudge in the right direction. All help is completely appreciated. -- Dangherous 13:31, 21 April 2006 (UTC)
Following on from this, how would I show that the path taken should be an arc of a circle with centre on the line y = -1/α? When I've tried this, I've done about 5 pages of working out, which is far too much I'm sure. What's the quickest way to get to the answer? Thanks awfully. -- Dangherous 11:26, 24 April 2006 (UTC)
The Euler-Lagrange equation for is
with the boundary conditions . Multiply by ,
Integrate,
Can anyone check my math and finish it from here? ( Igny 12:59, 24 April 2006 (UTC))
Thanks for checking the steps so far. The previous equation is equivalent to
where . Then solving it for results in
Denote and get
Integrate,
This looks like a circle. The unknown constants can be found from the boundary conditions on y. The center is on the line . Again I am not 100% sure I got all the steps right.( Igny 02:45, 25 April 2006 (UTC))
I have a huge number of equations in Latex, and I need to make a presentation in Powerpoint. Is there a way to convert equations from Latex to the equation editor format used in Powerpoint? I seriously hope there is! Thanks :) deeptrivia ( talk) 14:06, 24 April 2006 (UTC) PS: I know about Texpoint, but it doesn't seem to work for me. deeptrivia ( talk) 14:10, 24 April 2006 (UTC)
They also look a lot like Powerpoint.
Another approach is to use TeX4ht to convert to OpenOffice format (which stores the equations in MathML). OpenOffice can then export the document in MicroSoft formats, although it also includes a presentation package of its own ( Impress). -- Avenue 10:32, 26 April 2006 (UTC)
Solve this simultaneous equation?
Find the value for a + t if:
You may use this equation to help you:
The web can solve it for you. http://home.ubalt.edu/ntsbarsh/Business-stat/otherapplets/SysEq.htm
Ohanian 23:24, 24 April 2006 (UTC)
What kind of stupid exam question would ask for a+t? And if you know a and you know t then logically you would know a+t, it sounds like an exam question purely for the sake of an exam question without any real use in real life. Ohanian 03:09, 25 April 2006 (UTC)
Does the surface with equation z = xy have a name? I'm curious because it looks a little like a hyperbolic paraboloid, and the equation is similar to the reciprocal function xy = k (ie y = k/x), which is a hyperbola. -- 72.140.146.246 01:00, 25 April 2006 (UTC)
The group theory I did in my computer science courses is getting amazingly rusty. I know that is the group of all of the numbers from 1 to (p - 1) under multiplication, and has a lot of nice properties, but I can't remember the other names for it. Could someone point me to the article on that group? I'll be happy to create some redirects from Zp* or Z_p^*, to make finding the article easier. Thanks! -- Creidieki 01:01, 25 April 2006 (UTC)
Long, long ago, when the Internet was still young and lived under the name of Sanders (or at the very least with a sign out front reading "COMMERCIAL INTERESTS WILL"), I obtained undergraduate degrees in computer science and applied mathematics. In the case of the math degree, I'd already completed some advanced coursework in high school, so I entered college taking courses in linear algebra and differential equations. None of that is intended to impress anyone; in fact, just the opposite, because after I wasted the next ten years trying in vain to convince myself that a lucrative career in the computer industry was the route to happiness and financial success, I finally gave up (just wasn't good at programming for a living -- I'm too social). Before long I found myself tutoring at the local community college, and I've discovered that while I'm very good at helping students learn pre-algebra, algebra, and geometry, when the topic turns to more advanced matters, like trig or calculus, I start to falter... and pretty much everything I learned in college I've now forgotten. Diff EQ's, Linear, abstract, even advanced calc -- gone from, or buried somewhere in, my brain.
Now I'm considering teaching math for a living, preferably at the high school level, and I have a feeling I'm going to have to pursue an advanced math degree at some point. But I don't have any of my old textbooks, which makes it harder to re-learn all that stuff. And that brings me to my question: besides the Wikibooks and the stuff in this portal, which strike me as neither complete (yet) nor conveniently set up for structured learning (yet), where can I go online, or what books should I buy? If I need to start investing in textbooks again (my wallet trembles at the idea), which ones do you recommend?
Thanks for any advice you can offer! -- Jay (Histrion) ( talk • contribs) 20:02, 25 April 2006 (UTC)
Hi, i'm currently doing a maths degree (although i'm guessing on the other side of the atlantic) and i find that the schaum's outline series are very helpful and very cheap. they are appaulingly edited but all things considered they're superb.
Let's say Q = arctan(.5*tan(P)). Generally speaking,
However, if P equals either 0 or 90°, then Q = P. Now consider
If Pm = 45°, Qm ≈ 26.565°. If you wanted to integrate between Qf and Qc, but using even spacing (i.e., so that Qm = .5*[Qf + Qc]), how would you define/describe it? Does either the integral or interval have a special name?
~Kaimbridge~
12:47, 26 April 2006 (UTC)
Which type of image has a better resolution and is sharper? Patchouli 05:06, 27 April 2006 (UTC)
Thank you. Patchouli 06:51, 27 April 2006 (UTC)
What are affine varieties and how do they relate with grobner bases? Is there any other type(s) of varieties apart from affines if there what are they and how do they differ from the affine varieties? —The preceding unsigned comment was added by Nkomali ( talk • contribs) .
If sine can be defined within a triangle,how about sine hyperbolic?? —The preceding unsigned comment was added by 210.212.194.215 ( talk • contribs) .
In Matlab, is there a loop-free way to create an nxn matrix with diagonal and upper-triangular entries equal to 1, and lower-triangular entries equal to 0?
eg. for n = 3:
[ 1 1 1; 0 1 1; 0 0 1]
Confusing Manifestation 12:45, 27 April 2006 (UTC)
repmat(1:n,n,1)'<=repmat(1:n,n,1), triu(ones(n)),
cumsum(eye(n), 2), fliplr(hankel(ones(1,n))), inv(eye(n) - diag(ones(1, n - 1), 1)), !!(eye(n) + diag(ones(1, n - 1), 1))^n,
Thanks for all of those suggestions. I'll use Jitse's version just because at a quick glance it seems to be fairly simple, although it's nice to know the alternatives exist. (First rule of Matlab: there's almost always at least one loop-free way to do something.) Confusing Manifestation 00:31, 28 April 2006 (UTC)
Is the continuos image of a complete metric space necessarily complete? (Prove or give counter example) Nkomali.
What are the properties and applications of groebner bases. --Nkomali Nkomali 14:07, 27 April 2006 (UTC)
Show that the spaces l power alpha, the set of all bounded sequences aaaa9 in R or C with norm xn = sup{\xn\}, is a normed linear space. Show also that l power alpha is a complete normed linear space with the transition invariant d(x,y) = sup subscript j in N absolute value of the difference between epsilon j and mu of j.-- Nkomali 14:26, 27 April 2006 (UTC)
hi, can anyone explain to me what does the 'unpredictable, yet deterministic' behaviour of things in chaos theory means?... I don't get it :|, how can something be 'unpredictable yet deterministic'? If we find it's deterministic, aren't we somehow making it predictable?.-- Cosmic girl 15:55, 27 April 2006 (UTC)
Thank you! :) -- Cosmic girl 19:41, 27 April 2006 (UTC)
If I have a random variable Z = aX + bY, what is the characteristic function of Z in terms of the pdfs of X and Y? -- HappyCamper 16:34, 27 April 2006 (UTC)
I HAVE A RECTANGULAR TANK MEASURING 55 METRES BY 48 METRES CONTAINING 33 LITERS OF WATER. HELP ME FIND THE DEPTH OF THE WATER. —Preceding unsigned comment added by 208.131.187.81 ( talk • contribs) 02:22, 28 April 2006
Convert the volume from units in litres to units in metre cube and the answer is as plain as daylight. Ohanian 09:15, 28 April 2006 (UTC)
Do you perhaps mean centimeters (cm)? You could always convert to chains and hogsheads.... Skittle 23:24, 1 May 2006 (UTC)
How would you go about doing the question below...
All I could think of was changing 2sin²θ-1 into -2cos²θ + 1. I can't change sinθcosθ (at least I don't think so). I tried the right hand side next, and I got:
By the way, I keep on getting Failed to parse (lexing error) whenever I try to properly write a fraction, I just copied and pasted one from this page and changed it to this question but it still doesn't work, sorry about that. Thanks
C-c-c-c 03:34, 28 April 2006 (UTC)
How much money do I need to retire? And what % return can I expect to get from investing?
If I can achive X% Average return, does that mean I can always take out X% of the princaple each year? 12.183.203.184 03:52, 28 April 2006 (UTC)
How to calculate various interest rate problem ----------------------------------------------
extremely long post cut by me. For full version, see this diff. - lethe talk + 09:25, 28 April 2006 (UTC)
What are duplex numbers? Ohanian 09:06, 28 April 2006 (UTC)
Some board games or maps use squares (4 exits from every cell, or 8 if you include diagonals, but the latter are not the same distance away as the former), some use hexes (6 equidistant exits), some use triangles. Is it possible for a map to use other shapes, and allow other numbers of possible equal exists besides 4, 6 or 3? Is it possible to have with 8, for instance? Or why is it impossible? The shape doesn't have to be symmetrical, but ideally the exit points should be as equidistant as possible from the centre of one to the centre of another.-- Sonjaaa 10:28, 28 April 2006 (UTC)
Dear Wikipedians. I'll be very pleased if I'll the solution for the following geometrical rider: ABC is a triangle in which angle B = 2 angle C. D is a point on BC such that AD bisects angle BAC and AB=CD. Prove that angle BAC=72 degrees.
Thank you very much. User Akshitapatel
Hello fellow Wikipedians. Today I had the unfortunate task of writing a trig test (but I don't think it went too bad for that matter), and the question below stumped me.
Use only sec x:
I didn't know what to do, and I looked at all the formulas on the formula sheet to see how I could convert sin x into anything, but alas, nothing. The question below has to be in terms of sec x, that's the challenging part. I spent a good deal towards the end trying to think this through, and all I could come up was converting sin x into 1/cscx, but that didn't help either. Also, I converted sin 2x into 2sinxcosx (edited) I believe or something similar, I don't know it off the top of my head. Any thoughts on this would be greatly appreciated. --- C-c-c-c 22:52, 28 April 2006 (UTC)
I have an OT question—I've just recently administered my first final exam as an instructor in Canada, and have come across this usage of "write an exam", which confuses me a little. If the student writes the exam, just what is it the instructor does, when creating it? Isn't that also "writing", or is there a different verb used? -- Trovatore 23:55, 28 April 2006 (UTC)
Right, never mind, I did confuse it, but I think it was 2sinxcosx I had on the bottom, whatever it was, I got it from the identity sin 2x on my formula sheet. ---
C-c-c-c
02:44, 29 April 2006 (UTC)
So, you got as far as:
What did you do next? Melchoir 04:23, 29 April 2006 (UTC)
Today we started learning trig in my geometry class (our teacher calls it plain-vanilla trig, as it does get harder) and we learned the simplest of rules. We took notes, started on homework with extra class time, etc. When I got home to finish, I found some one had taken my notes and homework (while it is entirely possible I just lost them on the floor at school somewhere, I will stick with them being stolen). What I need to do is just make sure I'm sure. Sine=Opposite side/Hypotenuse; Cosine=Adjacent side/Hypotenuse; Tangent=opposite side/Adjacent side; Area= (1/2)(angle a)(angle b)(sinC). I pretty sure about all but the last one. If any corrections are needed please help me. Thanks. schyler 00:05, 29 April 2006 (UTC)
Thank you. Now that you mention it, my teacher did tell us this story about an indian princess named Sohcahtoa. I forgot. Also, that is the formula I was thinking of. Again, thanks. schyler 01:32, 30 April 2006 (UTC)
I have been looking through the proofs of the rules of differential calculus, and I understand how we find d/dx(x^n)=nx^(n-1) (something I was taught to take for granted), as well as the quotient rule and d/dx(sin x) and d/dx(cos x). However, I reached a stumbling block with the proof of the Chain rule. From the first line:
I assume this was reached by:
Where did the epsilon(delta) come from?
Also, in the proof of the product rule (which is more clearly laid out), it is said that:
I assume this is done with some sort of factorisation, but nothing I can see. The two terms on the left have no common factor. What am I missing?
Thanks in advance. -- Alexs letterbox 05:00, 29 April 2006 (UTC)
Hi,
I would like to know the difference between Absolute Graph and Relative Graph? I have searched all over the internet and i havent found any information. Its not even in my college notes. Any help would be appreciated as i have no idea what absolute and relative graphs are!
Please help me out. Thanks!
Its for my assignment for Quantitative Maths. I am stumped at it too!
Hey thanks alot. Atleast that gave me some idea. Maybe i will be able to expand on it but any new info is always welcome. thanks!
If you gave us some context, we might be able to make good educated guesses. What course is this for? - lethe talk + 09:19, 29 April 2006 (UTC)
Quantitative Maths. I have my asked my instructor and hopefully she will respond quickly. Its an online course.
Hi is the Newton who created the Newton-Rapson Method (for finding roots of an equation) Sirr Isac Newton. (the apple one)
Hello, everyone. I'm interested in making my own "book on tape" type of project, except on a CD which is made with my computer. Does anyone know what I would need to do this and what software I could use, preferably downloadable for free from the internet from a site such as tucows? Thanks. -- Think Fast 01:13, 30 April 2006 (UTC)
Say shoppers enter a shop at a mean rate of 4 per minute. This can be modeled as an exponential distribution parameter 0.25. How do you show that the difference in times between successive shoppers entering is distributed exponentially as well? Is this to do with Exponential distribution#Memorylessness? x42bn6 Talk 12:53, 30 April 2006 (UTC)
Are there any formal names for 3-focus, 4-focus, etc. ellipse-like shapes?
Tuvwxyz 18:53, 30 April 2006 (UTC)
i need help find it some definitions for word like PI,ratio ect where i can look?