Commit 4fdfcddf authored by Jay Belanger's avatar Jay Belanger
Browse files

* 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.
parent 14beddf4
2011-02-01 Jay Belanger <jay.p.belanger@gmail.com>
* 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 <acm@muc.de>
 
* progmodes/cc-cmds.el (c-forward-over-illiterals): Continue
......
......@@ -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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