5 ;;; (c) 2006 Mark Wooding
8 ;;;----- Licensing notice ---------------------------------------------------
10 ;;; This program is free software; you can redistribute it and/or modify
11 ;;; it under the terms of the GNU General Public License as published by
12 ;;; the Free Software Foundation; either version 2 of the License, or
13 ;;; (at your option) any later version.
15 ;;; This program is distributed in the hope that it will be useful,
16 ;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;;; GNU General Public License for more details.
20 ;;; You should have received a copy of the GNU General Public License
21 ;;; along with this program; if not, write to the Free Software Foundation,
22 ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
24 (defpackage #:mdw.factorial
26 (:export #:factorial))
27 (in-package #:mdw.factorial)
30 "Compute a factorial. This is a little bit optimized: we try to multiply
31 values which are similar in size."
33 (error "negative factorial argument ~A" n))
39 (unless stack (return))
40 (let ((top (car stack)))
41 (when (< f top) (return))
45 (do ((stack stack (cdr stack))
46 (a 1 (* a (car stack))))
49 ;;;----- That's all, folks --------------------------------------------------