Factorial in Ruby

Example for versions Ruby 1.8.5

This example uses recursive factorial definition. 

#! /usr/bin/env ruby
def factorial(n)
    if n == 0
        1
    else
        n * factorial(n - 1)
    end
end

0.upto(16) do |n|
    print(n, "! = ", factorial(n), "\n")
end