From: michael schuldt <mbschuldt@gmail.com>
Date: Tue, 18 Apr 2017 18:24:37 +0000 (-0700)
Subject: Use iteration in math-factorial-iter
X-Git-Tag: emacs-26.0.90~521^2~599
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=d831312d668fbedeffe3711b13cd455309da84a1;p=emacs.git

Use iteration in math-factorial-iter

* lisp/calc/calc-comb.el (math-factorial-iter):
Use iteration instead of recursion to avoid max-specpdl-size problem.
Copyright-paperwork-exempt: yes
---

diff --git a/lisp/calc/calc-comb.el b/lisp/calc/calc-comb.el
index c84ff236851..91fbb7b2b8a 100644
--- a/lisp/calc/calc-comb.el
+++ b/lisp/calc/calc-comb.el
@@ -362,11 +362,13 @@
     (math-gammap1-raw '(float -25 -2))))
 
 (defun math-factorial-iter (count n f)
-  (if (= (% n 5) 1)
-      (math-working (format "factorial(%d)" (1- n)) f))
-  (if (> count 0)
-      (math-factorial-iter (1- count) (1+ n) (math-mul n f))
-    f))
+  (while (> count 0)
+    (if (= (% n 5) 1)
+	(math-working (format "factorial(%d)" (1- n)) f))
+    (setq count (1- count)
+	  f (math-mul n f)
+	  n (1+ n)))
+  f)
 
 (defun calcFunc-dfact (n)   ; [I I] [F F] [Public]
   (cond ((Math-integer-negp n)