From c81cdb47b916a151284926e6616e82b3062b7fe9 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Fri, 3 Mar 2006 14:34:30 +0000
Subject: [PATCH] fix expt on negative powers of -inf.0 and +inf.0

svn: r2355
---
 src/mzscheme/src/number.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/mzscheme/src/number.c b/src/mzscheme/src/number.c
index d91d19fa14..56f75b253f 100644
--- a/src/mzscheme/src/number.c
+++ b/src/mzscheme/src/number.c
@@ -1857,16 +1857,30 @@ static double sch_pow(double x, double y)
   } else if (MZ_IS_POS_INFINITY(x)) {
     if (y == 0.0)
       return 1.0;
+    else if (y < 0)
+      return 0.0;
     else
       return scheme_infinity_val;
   } else if (MZ_IS_NEG_INFINITY(x)) {
     if (y == 0.0)
       return 1.0;
     else {
-      if (fmod(y, 2.0) == 1.0)
-	return scheme_minus_infinity_val;
-      else
-	return scheme_infinity_val;
+      int neg = 0;
+      if (y < 0) {
+	neg = 1;
+	y = -y;
+      }
+      if (fmod(y, 2.0) == 1.0) {
+	if (neg)
+	  return scheme_floating_point_nzero;
+	else
+	  return scheme_minus_infinity_val;
+      } else {
+	if (neg)
+	  return 0.0;
+	else
+	  return scheme_infinity_val;
+      }
     }
   } else
     return pow(x, y);