* lisp/calc/calc.el: Silence byte-compiler warnings

[gnu-emacs] / lisp / calc / calc-mtx.el

diff --git a/lisp/calc/calc-mtx.el b/lisp/calc/calc-mtx.el
index b334f3594c2392ea2fb56d82c93dddb44eb70c7f..b8c5ff910933750507db46f6ab103bf68b770c41 100644 (file)
--- a/lisp/calc/calc-mtx.el
+++ b/lisp/calc/calc-mtx.el
@@ -1,7 +1,6 @@
 ;;; calc-mtx.el --- matrix functions for Calc
 
-;; Copyright (C) 1990, 1991, 1992, 1993, 2001, 2002, 2003, 2004,
-;;   2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+;; Copyright (C) 1990-1993, 2001-2015 Free Software Foundation, Inc.
 
 ;; Author: David Gillespie <daveg@synaptics.com>
 ;; Maintainer: Jay Belanger <jay.p.belanger@gmail.com>
@@ -233,6 +232,20 @@
          (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))
@@ -262,7 +275,7 @@
                                            (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)))
@@ -365,5 +378,4 @@
 
 (provide 'calc-mtx)
 
-;; arch-tag: fc0947b1-90e1-4a23-8950-d8ead9c3a306
 ;;; calc-mtx.el ends here