gcd2

# File lib/mathn.rb, line 19
  def gcd2(int)
    a = self.abs
    b = int.abs
    a, b = b, a if a < b
    
    pd_a = a.prime_division
    pd_b = b.prime_division
    
    gcd = 1
    for pair in pd_a
      as = pd_b.assoc(pair[0])
      if as
        gcd *= as[0] ** [as[1], pair[1]].min
      end
    end
    return gcd
  end