From 07d5a9e3857f9f4f243b3f4891b1ff1b0d087698 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Tue, 1 Jan 2013 12:31:24 -0700
Subject: [PATCH] fix `expt' on small negative number and large positive odd

The pow() function apparently gets it wrong on some platforms.

Closes PR 13391
---
 collects/mred/private/wx/gtk/frame.rkt |  1 +
 collects/tests/racket/number.rktl      |  4 ++++
 src/racket/src/number.c                | 11 ++++++++++-
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/collects/mred/private/wx/gtk/frame.rkt b/collects/mred/private/wx/gtk/frame.rkt
index f39ce65295..d5191f5e1d 100644
--- a/collects/mred/private/wx/gtk/frame.rkt
+++ b/collects/mred/private/wx/gtk/frame.rkt
@@ -406,6 +406,7 @@
 
     (define focus-here? #f)
     (define/override (on-focus? on?)
+      (unless on? (on-menu-click))
       (on-focus-child on?)
       (cond
        [on?
diff --git a/collects/tests/racket/number.rktl b/collects/tests/racket/number.rktl
index 83c5bdb4dc..c2c1e044de 100644
--- a/collects/tests/racket/number.rktl
+++ b/collects/tests/racket/number.rktl
@@ -548,6 +548,10 @@
 (test (- (expt 5 29)) min (- (expt 5 29)) (expt 5 27))
 (test (- (expt 5 29)) min (- (expt 5 27)) (- (expt 5 29)))
 (test (- (expt 5 29)) min (- (expt 5 29)) (- (expt 5 27)))
+(test 0.0 expt -0.1 10000000000000.0)
+(test -0.0 expt -0.1 10000000000001.0)
+(test 0.0 expt -0.0 10000000000000.0)
+(test -0.0 expt -0.0 10000000000001.0)
 
 (err/rt-test (max 0 'a))
 (err/rt-test (min 0 'a))
diff --git a/src/racket/src/number.c b/src/racket/src/number.c
index d58955c60a..2ecec0860f 100644
--- a/src/racket/src/number.c
+++ b/src/racket/src/number.c
@@ -2729,7 +2729,16 @@ static double sch_pow(double x, double y)
         return scheme_infinity_val;
     }
   } else {
-    return protected_pow(x, y);
+    double r;
+    r = protected_pow(x, y);
+    if ((r == 0.0) && !minus_zero_p(r)) {
+      /* check large odd power of a small negative number,
+         which some libraries get wrong for some reason */
+      if ((x < 0) && (fmod(y, 2.0) == 1.0)) {
+	r = scheme_floating_point_nzero;
+      }
+    }
+    return r;
   }
 }
 #endif