source: trunk/j/src/org/armedbear/lisp/lcm.lisp @ 9266

Last change on this file since 9266 was 5805, checked in by asimon, 17 years ago

error report

File size: 1.4 KB
Line 
1;;; lcm.lisp
2;;;
3;;; Copyright (C) 2003 Peter Graves
4;;; $Id: lcm.lisp,v 1.2 2004-02-13 08:34:24 asimon Exp $
5;;;
6;;; This program is free software; you can redistribute it and/or
7;;; modify it under the terms of the GNU General Public License
8;;; as published by the Free Software Foundation; either version 2
9;;; of the License, or (at your option) any later version.
10;;;
11;;; This program is distributed in the hope that it will be useful,
12;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
13;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14;;; GNU General Public License for more details.
15;;;
16;;; You should have received a copy of the GNU General Public License
17;;; along with this program; if not, write to the Free Software
18;;; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
19
20(in-package "SYSTEM")
21
22(defun two-arg-lcm (n m)
23  (cond ((zerop n) 0)
24        ((zerop m) 0)
25        (t
26         (/ (abs (* n m)) (gcd n m)))))
27
28(defun lcm (&rest integers)
29  (unless (every #'integerp integers)
30    (error 'type-error :datum (find-if-not #'integerp integers) :expected-type 'integer))
31  (case (length integers)
32    (0 1)
33    (1 (abs (car integers)))
34    (2 (two-arg-lcm (car integers) (cadr integers)))
35    (t
36     (do ((result (car integers) (two-arg-lcm result (car rest)))
37          (rest (cdr integers) (cdr rest)))
38         ((null rest) result)))))
Note: See TracBrowser for help on using the repository browser.