Hi kingkongrevenge

The book Mastering Algorithms with Perl by Jon Orwant, Jarkko Hietaniemi, and John Macdonald provides the code to compute several probability distributions (the geometric distribution included). The source code is available at http://examples.oreilly.com/maperl/ (once you uncompress the file, the code will be in the file "distributions" inside the ch14 folder).

I hope this helps.

Cheers,