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[Emacs-diffs] /srv/bzr/emacs/trunk r103060: * calc/calc-mtx.el (math-lud
From: |
Jay Belanger |
Subject: |
[Emacs-diffs] /srv/bzr/emacs/trunk r103060: * calc/calc-mtx.el (math-lud-pivot-check): New function. |
Date: |
Mon, 31 Jan 2011 20:15:52 -0600 |
User-agent: |
Bazaar (2.0.3) |
------------------------------------------------------------
revno: 103060
committer: Jay Belanger <address@hidden>
branch nick: trunk
timestamp: Mon 2011-01-31 20:15:52 -0600
message:
* calc/calc-mtx.el (math-lud-pivot-check): New function.
(math-do-matrix-lud): Use `math-lud-pivot-check' to check the size
of potential pivots.
modified:
lisp/ChangeLog
lisp/calc/calc-mtx.el
=== modified file 'lisp/ChangeLog'
--- a/lisp/ChangeLog 2011-01-31 23:54:50 +0000
+++ b/lisp/ChangeLog 2011-02-01 02:15:52 +0000
@@ -1,3 +1,9 @@
+2011-02-01 Jay Belanger <address@hidden>
+
+ * calc/calc-mtx.el (math-lud-pivot-check): New function.
+ (math-do-matrix-lud): Use `math-lud-pivot-check' to check the size
+ of potential pivots.
+
2011-01-31 Alan Mackenzie <address@hidden>
* progmodes/cc-cmds.el (c-forward-over-illiterals): Continue
=== modified file 'lisp/calc/calc-mtx.el'
--- a/lisp/calc/calc-mtx.el 2011-01-25 04:08:28 +0000
+++ b/lisp/calc/calc-mtx.el 2011-02-01 02:15:52 +0000
@@ -232,6 +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))
@@ -261,7 +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)))
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Jay Belanger <=