;;; calc-mtx.el --- matrix functions for Calc
-;; Copyright (C) 1990, 1991, 1992, 1993, 2001, 2002, 2003, 2004,
-;; 2005, 2006, 2007 Free Software Foundation, Inc.
+;; Copyright (C) 1990-1993, 2001-2011 Free Software Foundation, Inc.
;; Author: David Gillespie <daveg@synaptics.com>
-;; Maintainer: Jay Belanger <belanger@truman.edu>
+;; Maintainer: Jay Belanger <jay.p.belanger@gmail.com>
;; This file is part of GNU Emacs.
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
;; GNU Emacs is distributed in the hope that it will be useful,
-;; but WITHOUT ANY WARRANTY. No author or distributor
-;; accepts responsibility to anyone for the consequences of using it
-;; or for whether it serves any particular purpose or works at all,
-;; unless he says so in writing. Refer to the GNU Emacs General Public
-;; License for full details.
-
-;; Everyone is granted permission to copy, modify and redistribute
-;; GNU Emacs, but only under the conditions described in the
-;; GNU Emacs General Public License. A copy of this license is
-;; supposed to have been given to you along with GNU Emacs so you
-;; can know your rights and responsibilities. It should be in a
-;; file named COPYING. Among other things, the copyright notice
-;; and this notice must be preserved on all copies.
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
(setq math-lud-cache (cons (cons m entry) math-lud-cache)))
lud))))
+
+(defun math-lud-pivot-check (a)
+ "Determine a useful value for checking the size of potential pivots
+in LUD decomposition."
+ (cond ((eq (car-safe a) 'mod)
+ (if (and (math-integerp (nth 1 a))
+ (math-integerp (nth 2 a))
+ (eq (math-gcd (nth 1 a) (nth 2 a)) 1))
+ 1
+ 0))
+ (t
+ (math-abs-approx a))))
+
+
;;; Numerical Recipes section 2.3; implicit pivoting omitted.
(defun math-do-matrix-lud (m)
(let* ((lu (math-copy-matrix m))
(nth j (nth k lu))))
k (1+ k)))
(setcar (nthcdr j (nth i lu)) sum)
- (let ((dum (math-abs-approx sum)))
+ (let ((dum (math-lud-pivot-check sum)))
(if (Math-lessp big dum)
(setq big dum
imax i)))
(provide 'calc-mtx)
-;;; arch-tag: fc0947b1-90e1-4a23-8950-d8ead9c3a306
;;; calc-mtx.el ends here