## #math - Fri 9 Mar 2007 between 11:21 and 12:11

### NY Lost Funds

 chessguy this might be helpful http://en.wikipedia.org/wiki/Joint_probability_density_function#Probability_function_associated_to_multiple_variables MrFreak yeah i'm reading that right nowI guess it would be likePr(x >= 0, 0 <= y <= e^-x) Integral 0 to infinity Integral 0 to 1 e^-x dx dy?does that look right? kmh MrFreak : well do you have info for outside the region ? MrFreak info for outside the region?i assume outside the region is always 0 kmh the probabilty outside the region is 0 ?ah okyou need an interval for x thoughas the area under the curve needs to be limitedor bounded rather MrFreak interval for x would be 0 to infinity i think kmh hmmm yes if the improper integral exists that's good enough MrFreak e^-x approaches 0 asymptotically kmh but you need the area under the curve first so that you can norm the measure to 1oh it is 1 anyway :) MrFreak so how do i set up the integral for the area under the curve? jhardin quick question, can anyone think of any hermitian unitary matrices that aren't just a string of +-i's along the diagonal, or antidiagonalerr, anti-hermitian kmh MrFreak : i*m a bit rusty too with n-dim distribution, but i think it looks like thatP(X=0 which is true.Can I conclude Xn is bounded by 1 from above?:one1?:P MrFreak so how simplyy do i find the area under the curve y = e^-xfrom x = 0 to infinity?the joint density will just be 1/area, since it's uniformly distributedintegral from 0 to infinity of e^-x? chessguy that's just a simple improper integral MrFreak heh, i'm a CS major, and the last time i did an integral was calc 3 two years ago chessguy take the limit as M goes to infinity of the integral from 0 to M MrFreak i sort of hazily remember the terms integration by parts and u substitution chessguy i was a CS major too :)