# Recent content by Sane

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

Thanks for the reply. I was hoping I could have the null hypothesis set up such that I would be rejecting the null-hypothesis of dependence. This should permit me to know when there is evidence to suggest that the two variables are dependent, right? If that is the case, then my earlier comment...
2. ### 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...
3. ### Using Simulation for Graph Visualization

I have been thinking about this for quite a while, and thought of the following simulation: for node in graph: node.x = <arbitrary value near 0> must be distinct per row node.velocity = 0 for number of STEPS: for node in graph: node.accel = 0 for node's row...
4. ### 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...
5. ### Coefficients in expansion of product(1-x^a, a=1n)?

I stumbled across an interesting connection between partitioning n into k parts from any finite subset of the natural numbers and the partition functions p(n) and q(n). To be precise, if n,k are non-negative integers, S \subset \mathbb{N}, and S has a maximum: Let p_{S-k}(n) be the number of...
6. ### Coefficients in expansion of product(1-x^a, a=1n)?

I just found an excellent resource. http://functions.wolfram.com/IntegerFunctions/PartitionsQ/introductions/Partitions/ShowAll.html It covers both of the functions you mentioned, p(n) (unordered partitions of n with repetition) and q(n) (unordered partitions of n without repetition) concisely...
7. ### Coefficients in expansion of product(1-x^a, a=1n)?

That observation is related to the problem I was trying to solve! I realize now that a subproblem of what I'm doing is counting the number of ways to partition a natural number into any number of unordered positive parts. This equation was a piece of the resulting generating function (the part I...
8. ### 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...
9. ### Loop-the-loop in roller coaster

If friction and air resistance are negligible, it's a whole 'nother question you're dealing with. The change in velocity would depend entirely in the change in graviational potential energy (the vertical work done by gravity), otherwise energy is conserved and Ek is still the same. If Ek is...
10. ### Loop-the-loop in roller coaster

You would need more information, such as the loss of kinetic energy in the coaster, or the average force of friction.
11. ### Shining Light - The Physics Behind This Phenomenon?

That's one thing I wasn't clear on myself, and need to explain better once I understand it more. I don't think it's so much that it's bending it, but that the waves can go around obstacles. And that results in interference. Similar to the Double Slit Experiment. I think... Clarification, anyone?
12. ### Shining Light - The Physics Behind This Phenomenon?

I could not find an objective explanation of Diffraction Spikes anywhere... not even on Wikipedia. Most sites just referenced little things you could do, and the overall effect. I found a couple sites that explained very briefly what happens, so I tried to piece together all of these things to...
13. ### Shining Light - The Physics Behind This Phenomenon?

It seems like it'll be anything that obstructs light directly before entering the lens. You can even place strings in front of a telescope and get diffraction spikes (as russ_watters has apparently done).
14. ### Shining Light - The Physics Behind This Phenomenon?

Diffraction spikes, brilliant! Thanks. I get many excellent hits with this term. Thank-you.
15. ### Shining Light - The Physics Behind This Phenomenon?

It's always up with respect to the orientation of the camera. I took another picture to clarify: http://img142.imageshack.us/img142/9733/physicsphotorotatekn4.jpg [Broken] So I guess that means it has to do with the lens inside the camera. Is there anything specific I can research?