# Prevent uninterruptible infinite loop. This is the fix for
#    20270656 calc: sign change of hh.mm value puts Emacs into tight loop
# See components/emacs/README.
#
--- emacs-24.3.orig/lisp/calc/calc-forms.el	2013-01-01 13:37:17.000000000 -0700
+++ emacs-24.3/lisp/calc/calc-forms.el	2015-01-02 14:57:36.824358166 -0700
@@ -271,7 +271,10 @@
 	(m (math-normalize (nth 2 a)))
 	(s (let ((calc-internal-prec (max (- calc-internal-prec 4) 3)))
 	     (math-normalize (nth 3 a)))))
-    (if (math-negp h)
+    (if (or 
+         (math-negp h)
+         (and (= h 0) (math-negp m))
+         (and (= h 0) (= m 0) (math-negp s)))
 	(progn
 	  (if (math-posp s)
 	      (setq s (math-add s -60)