Can anyone help with how to draw random numbers from a Beta(a,b) distribution?  

I'm programming a Dirichlet Process Prior for rate categories but do not know of a built-in HyPhy function that draws from this distribution.

Does one already exist?  If so, can someone point me to source code or instructions on how to implement?

Any help will be much appreciated.  Thank you!

Hi Sam,

Sorry took me a while to answer. Look inside TemplateBatchFiles/Utility/ProbabilityDistributions.bf
It has a sampleFromBeta (p,q) function.

Use example:

[code]
LoadFunctionLibrary ("ProbabilityDistributions");

for (k = 0; k < 10; k += 1)
{
    fprintf (stdout, sampleFromBeta (5,5), "\n");
}

[/code]

Sergei

Thanks a bunch!  I was wondering where those distros are at.  

Sam