This is a little library I put together a while ago just for the hell of it. It won’t be developed any further.

Poisson is a Ruby class for the Poisson Distribution. Here is a very simple use example:

require 'poisson'
poisson = Poisson.new(6)
poisson.probability { |x| x == 4 } # => 0.133...

Please see the API documentation for more detail.

You know the routine:

gem install poisson

Poisson was written by Jonathan Leighton <j at jonathanleighton dot com> of jonathanleighton.com/.

Poisson is licensed under the GPL. See the LICENCE file. You can find the code at github.com/jonleighton/poisson/.