[git] CMU Common Lisp branch master updated. snapshot-2013-11-2-g20ee8ef

[Raymond Toy]

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- Log -----------------------------------------------------------------
commit 20ee8ef20cd01a0be841695d6beaf98968e5be31
Author: Raymond Toy <toy.raymond at gmail.com>
Date:   Thu Nov 7 22:33:42 2013 -0800

    Add shortcut for (expt -1 power).

diff --git a/src/code/irrat.lisp b/src/code/irrat.lisp
index 67ca060..927a5fb 100644
--- a/src/code/irrat.lisp
+++ b/src/code/irrat.lisp
@@ -318,11 +318,13 @@
 ;;; of power are calculated as positive integers, and inverted if negative.
 ;;;
 (defun intexp (base power)
-  ;; Handle the special case of 1^power.  Maxima sometimes does this,
-  ;; and there's no need to cause a continuable error in this case.
-  ;; Should we also handle (-1)^power?
+  ;; Handle the special case of 1^power and (-1)^power.  Maxima
+  ;; sometimes does this, and there's no need to cause a continuable
+  ;; error in this case.
   (when (eql base 1)
     (return-from intexp base))
+  (when (eql base -1)
+    (return-from intexp (if (oddp power) -1 1)))
   
   (when (> (abs power) *intexp-maximum-exponent*)
     ;; Allow user the option to continue with calculation, possibly

-----------------------------------------------------------------------

Summary of changes:
 src/code/irrat.lisp |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)


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