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Newbie  inverse method
Posted:
Apr 19, 2012 1:44 PM


Hey guys ,
This is my first time trying to work in matlab , and I need some help
I need to simulate a variable X with a density function and make its histogram. f(x)=(exp(1)/(exp(2)1))*exp(x) , x [1,1]
And i tried with the inverse method F^1=log(1+(exp(2)1)*U)1
My code n=100000; U=rand(1,n); X=log(1+(exp(2)1)*U)1; d=1/30; [r,s]=hist(X,30); r=r/(d*m); plot(s,r,?o?) hold on x=0:0.01:1; y=(exp(1)/(exp(2)1))*exp(x); plot(x,y) grid xlabel(?x?) ylabel(?density function?)
But i have errors and I'm not sure that my interpretation/understanding of the problem is that good , so I found a better code on User's Guide  which I don't understand.
mu = 1; X = expinv(rand(1e4,1),mu);
numbins = 50; hist(X,numbins) set(get(gca,'Children'),'FaceColor',[.8 .8 1]) hold on
[bincounts,binpositions] = hist(X,numbins); binwidth = binpositions(2)  binpositions(1); histarea = binwidth*sum(bincounts);
x = binpositions(1):0.001:binpositions(end); y = exppdf(x,mu); plot(x,histarea*y,'r','LineWidth',2)
So i was wondering if anyone can explain it to me ? There are some lines that i cannot find them .
Thank you !! And sorry for the bother !!



