# # This software is Copyright 2005 by Elsevier Inc. You may use it # under the terms of the license at http://perl.plover.com/hop/LICENSE.txt . # ### ### gcd ### ## Chapter 5 section 4.1 sub gcd { my ($m, $n) = @_; if ($n == 0) { return $m; } return gcd($n, $m % $n); }