gcdFast

gcdFast.m finds the greatest common denominator using a Euclid's algorithm.

Though the builtin function is sufficiently fast for practical purposes, this particular implementation is faster by a factor of 100 to 300 across a range of 6 to 13 digits. This is intended to be an interesting function rather than an attempt to replace anything. If a consistently faster method than this can be shown, I'll happily adapt this in the spirit of competition.