Search results

  1. S

    Need statistical test for contingency table with very small and big counts

    I have a 2x2 contingency table, and I want to discover how likely it is that the two events are dependent. The top-left cell is usually in the range of 1-10. The bottom-right cell can be over 3 billion. The other two cells are in the hundreds or millions (exclusively). I have tried Pearson's...
  2. S

    Using Simulation for Graph Visualization

    Firstly, let me excuse myself for not knowing the most appropriate location to post this question. This is a question pertaining to Graph Theory, but the heart of the application is intended to be driven by the math and/or simulation of classical physics. At work I am currently attempting to...
  3. S

    Coefficients in expansion of product(1-x^a, a=1n)?

    I have an equation of the form (1-x)(1-x^2)(1-x^3)\cdot\cdot\cdot(1-x^n). Or, in maple notation, product(1-x^a, a=1..n). I've been trying to find a way to express this as an expanded polynomial in sigma notation so that I can extract coefficients (for an enumerative generating function). If the...
  4. S

    Shining Light - The Physics Behind This Phenomenon?

    I've taken a picture of my christmas lights. I'm wondering if someone could help me explain, or at least name, the phenomenon? http://img142.imageshack.us/img142/5925/physicsphotocontestto9.jpg [Broken] Why does light appear to come from 4 distinct points around the light? Even though...
  5. S

    What If We Had Negative Mass?

    This isn't really a homework question... but it is homework... and I have a question... so I thought I might as well post it here. This is part of my grade 12 Physics curriculum. For our project, we're supposed to ask ourselves "What if <this happened>?" I chose to do mine on negative...
  6. S

    The Purpose Of A Community

    Online communities generally have several purposes, in my opinion. There are two that strike me as most important. The most obvious and prominent one is to learn through one another, and share information and opinions freely. But the other, equally important purpose, is to accomplish...
  7. S

    Integral - I can't get the right answer

    Find the volume of the solid obtained when the given region is rotated about the x-axis. Under y = (\sin{x})^{\frac{3}{2}} between 0 and pi. The radius is... r = (\sin{x})^{\frac{3}{2}} Then the area for any sample is... A (x) = \pi((\sin{x})^{\frac{3}{2}})^{2} Simplifying to... A...
  8. S

    Programming Challenge

    Disclaimer : This thread, and its solution, by no means suggests how to launch a network attack in real life. The purpose of this challenge is to learn how to decompose graphs and analyze them as efficiently as possible. There is no knocking down of network connections, or even speculations as...
  9. S

    Medical Ummm, Do I Have Some Sort Of Condition?

    I'm wondering if I have some sort of medical condition, if there's any term for this... or if it's just something that's fairly common... I haven't really talked to anyone about it, just wondering if anyone knew anything about this. When I was about 9 or 10, every month or so, my mind would...
  10. S

    Roots Of Unity - Is It Primitive?

    All right, thanks to everybody's help, I've got the algorithm for determining the nth roots of unity. However, for determining which ones are primitive, I'm still having a little trouble. If n is odd, I can test if (n, k) are coprime. However, for even values of n, it seems that it doesn't...
  11. S

    Solving A Differential Equation

    Given the two equations: y(1) = \pi \frac{dy}{dx} = \frac{6x^{2}}{2y + \cos{y}} Solve for x: \begin{align*} \int(2y+\cos{y})dy &= \int(6x^{2})dx\\ y^{2} + \sin{y} &= 2x^{3}\\ \end{align*} But in order to set a value to the function y, I need some way to exclude y and then plug...
  12. S

    A Simple Calculus Question I Can't Get

    I don't know why ... I've done every single question in the text book up to this point, and am now stumped on one of the easier ones. I've made my equation, and solved it, but it is not the correct answer. Nor does the correct answer make any sense. Either the back of the book is incorrect...
  13. S

    A Newer Build Of vBulletin

    A newer build of vBulletin supports "multi-quoting", where you toggle which posts you wish to quote, then click "quote" and find all of the posts you toggled inside the post you're going to write. I liked this feature because it's useful when you find yourself replying to more than one...
  14. S

    Monthly Food For Programmers

    I'm considering starting a journal, where every month I post an article that analyzes some aspect of programming subjectively. The article will consider a problem, analyze it in depth, and delve in to a solution with snippets. All the while, it will hopefully teach readers about some more...
  15. S

    Hmm? No Computer Science Forum?

    I know this is a Math and Physics forum, but I'm surprised to see there's nothing for programming/algorithms/computer science. There's even an Anthropology forum. I know there's a technology/computers forum, but that's not really the same thing. Has this been discussed before, or is there...
  16. S

    Schools Hoping For A Full Scholorship To A University

    I'm one year away from my final year in High School, and am hoping to get a full scholorship to one of the best Universities in Canada. I am hoping for Waterloo, but I'll probably go to whichever one will give me the most money. I haven't yet spoken with my guidance counsellor about specific...
  17. S

    Discrete Weighted Transform - A Primitive Nth Root of Unity

    Hello, I got pointed to this forum by OfficeShreder. I have a question I've been puzzling myself over for a while. I am currently trying to implement the "Discrete Weighted Transform". I have reached a step where I need to determine "a primitive Nth root of unity in the appropriate domain"...
Top