Scheme has a predefined procedure gcd
for computing the
greatest common divisor of zero or more integers. However, we should pause
to admire the bare beauty of Euclid's algorithm, as expressed in Scheme:
(define gcd (lambda (m n) (if (zero? n) m (gcd n (remainder m n)))))
This document is available on the World Wide Web as
http://www.math.grin.edu/~stone/events/scheme-workshop/gcd.html