code.delx.au - gnu-emacs-elpa/blob - packages/test-simple/example/gcd.el

   1 (defun gcd(a b)
   2   "Greatest Common Divisor of A and B"
   3   ;; Make a < b
   4   (if (> a b)
   5       (let ((c a))
   6         (setq a b)
   7         (setq b c)))
   8   (cond
   9    ((< a 0) nil)
  10    ((or (= 0 (- b a)) (= a 1)) a)
  11    (t (gcd (- b a) a))
  12    )
  13 )