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

NY Lost Funds



chessguythis might be helpful http://en.wikipedia.org/wiki/Joint_probability_density_function#Probability_function_associated_to_multiple_variables
MrFreakyeah i'm reading that right now
I guess it would be like
Pr(x >= 0, 0 <= y <= e^-x) Integral 0 to infinity Integral 0 to 1 e^-x dx dy?
does that look right?
kmhMrFreak : well do you have info for outside the region ?
MrFreakinfo for outside the region?
i assume outside the region is always 0
kmhthe probabilty outside the region is 0 ?
ah ok
you need an interval for x though
as the area under the curve needs to be limited
or bounded rather
MrFreakinterval for x would be 0 to infinity i think
kmhhmmm yes if the improper integral exists that's good enough
MrFreake^-x approaches 0 asymptotically
kmhbut you need the area under the curve first so that you can norm the measure to 1
oh it is 1 anyway :)
MrFreakso how do i set up the integral for the area under the curve?
jhardinquick question, can anyone think of any hermitian unitary matrices that aren't just a string of +-i's along the diagonal, or antidiagonal
err, anti-hermitian
kmhMrFreak : i*m a bit rusty too with n-dim distribution, but i think it looks like that
P(X<x,Y<y)=int(int(1_[0,e^(-x)](u),u=0..y),v=0..x)
and 1_[0,e^(-x)](u) is the indicator function
MrFreakhmm
CopterX_n+1= 3X_n/ (X_n^2+X_n+1), Xn=2007. I wanted to prove that its bounded above by 1.
So I did X_n+1 <=1 , 3X_n/ (X_n^2+X_n+1) <=1 and reached (X_n-1)^2 >=0 which is true.
Can I conclude Xn is bounded by 1 from above?
:o
ne1?
:P
MrFreakso how simplyy do i find the area under the curve y = e^-x
from x = 0 to infinity?
the joint density will just be 1/area, since it's uniformly distributed
integral from 0 to infinity of e^-x?
chessguythat's just a simple improper integral
MrFreakheh, i'm a CS major, and the last time i did an integral was calc 3 two years ago
chessguytake the limit as M goes to infinity of the integral from 0 to M
MrFreaki sort of hazily remember the terms integration by parts and u substitution
chessguyi was a CS major too :)

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