From: "erlercw@..." <erlercw@...>
Date: 2004-11-14T10:48:21+09:00
Subject: Re: mathn.rb is unacceptably slow (proposed replacements)

># Use a Euclidean GCD algorithm
>def gcd2(other)
>  min, max = [self.abs, other.abs].sort
>  min, max = max % min, min while min > 0
>  max
>end

Now that I think of it,

# Use a Euclidean GCD algorithm
def gcd2(other)
  min = self.abs
  max = other.abs
  min, max = max % min, min while min > 0
  max
end

will be even faster.  The sort isn't really needed, min = max % 
min will ensure that min is the true minimum in one step.