How do I create a random variable which is exponential with a mean of 2

Hey, I need to create a signal, X, which is exponential with a mean of 2. It is transmitted through an additive Gaussian noise channel where the Gaussian noise has a mean of -1 and a variance of 4. The signal and noise are independent.

I realize I have to use randn() for the random variable but am not really sure how to get a specific mean or how to produce the Gaussian. Have been away from MatLab for awhile. Any help would be greatly appreciated. Thanks! -Will

Answer 1

[bym]

if you have the statistics toolbox:

exprnd()

to roll your own

x = -2*log(rand)

[Will]

thanks

Answer 2

[Will]

Thanks didn't even realize I had the stats toolbox. Any ideas on how to produce the additive Gaussian noise channel?

[bym]

agwn = 4*randn(size(A))-1

[bym]

whoops should be

agwn = 2*randn(size(A))-1 %multiply by standard deviation *not* variance, sorry

[Will]

Appreciate it