# Search results

1. ### Probability Density of a Constrained Chi-Square

Hello PF! It's been a while. How are things? In my research I'm faced with determining a probability distribution from a function built as follows: Perform three measurements X, Y, Z that have normally distributed errors. Impose a constraint and variable change that allows me to...
2. ### Using Correlation to Predict Values

I've searched the forums but am unable to find an answer to this: Given two variables with a correlation, you can predict one from the other using the familiar E(Y|X) = EY + r * s_y * (X - EX) / s_x What I want to know is how to predict values from multiple variables, especially when these...
3. ### Enumerating Combinations

I am facing an issue in my research where I need to enumerate all combinations of an underlying set. BUT the set has some special features. Here is an example: Given a set {A,B,C,D,E, F} where each item in the set consists of two values. Something like: A = (1,2) B = (3,4) C = (5,6)...
4. ### Quantum Group Theory

I'm looking for a good introduction on quantum group theory for someone who has already had a semester class on group theory. I'll be putting together a short paper (5 pages) on the topic with the intended audience of college math majors. My naive understanding is that symmetry and interaction...
5. ### Atmospheric Dissipation

Anyone have a link or direct info regarding the rate at which the earth's atmosphere dissipates into space? I'm looking for both an estimate of the current rate as well as a model (time and mass dependencies). Thanks.