Dear `stan`

community, I am facing the following programming problem writing my own log probability mass function for the multivariate Fisher & Wallenius’ non central hypergeometric distributions.

Given two positive integers n and c>1, I would like to build a matrix of integers with c columns and

\frac{(n+c-1)!}{n!(c-1)!} rows.

To calculate the factorials i use the `tgamma()`

function, so that \Gamma(n+1) = n!.

However `tgamma`

returns real values and I cannot pass real values a s dimension of a matrix.

Any workaround?

Thanks in advance.