Fix pow (0.0, -Inf) (bug 14241).

diff --git a/ChangeLog b/ChangeLog
index f632292..f066a88 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2012-06-15  Joseph Myers  <joseph@codesourcery.com>
+
+       [BZ #14241]
+       * sysdeps/ieee754/dbl-64/e_pow.c (__ieee754_pow): Use 0.0 instead
+       of ABS(x) in calculating zero to negative powers other than odd
+       integers.
+       * math/libm-test.inc (pow_test): Add more tests.
+
 2012-06-15  Andreas Jaeger  <aj@suse.de>
 
        * manual/contrib.texi (Contributors): Update entry of Liubov

diff --git a/NEWS b/NEWS
index 91b2644..96b351c 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -29,7 +29,7 @@ Version 2.16
   13963, 13967, 13968, 13970, 13973, 13979, 13983, 13986, 13996, 14012,
   14027, 14033, 14034, 14036, 14040, 14043, 14044, 14048, 14049, 14053,
   14055, 14059, 14064, 14075, 14080, 14083, 14103, 14104, 14109, 14112,
-  14122, 14123, 14134, 14153, 14183, 14188, 14199, 14210, 14218
+  14122, 14123, 14134, 14153, 14183, 14188, 14199, 14210, 14218, 14241
 
 * Support for the x32 ABI on x86-64 added.  The x32 target is selected by
   configuring glibc with:

diff --git a/math/libm-test.inc b/math/libm-test.inc
index d32dde3..8e4d02e 100644 (file)
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -6290,6 +6290,8 @@ pow_test (void)
   TEST_ff_f (pow, minus_zero, 11.1L, 0);
   TEST_ff_f (pow, 0, plus_infty, 0);
   TEST_ff_f (pow, minus_zero, plus_infty, 0);
+  TEST_ff_f (pow, 0, minus_infty, plus_infty, DIVIDE_BY_ZERO_EXCEPTION_OK);
+  TEST_ff_f (pow, minus_zero, minus_infty, plus_infty, DIVIDE_BY_ZERO_EXCEPTION_OK);
 
 #ifndef TEST_INLINE
   /* pow (x, +inf) == +inf for |x| > 1.  */

diff --git a/sysdeps/ieee754/dbl-64/e_pow.c b/sysdeps/ieee754/dbl-64/e_pow.c
index 6c41af9..3fd5e65 100644 (file)
--- a/sysdeps/ieee754/dbl-64/e_pow.c
+++ b/sysdeps/ieee754/dbl-64/e_pow.c
@@ -112,12 +112,12 @@ __ieee754_pow(double x, double y) {
     if (((v.i[HIGH_HALF] & 0x7fffffff) == 0x7ff00000 && v.i[LOW_HALF] != 0)
        || (v.i[HIGH_HALF] & 0x7fffffff) > 0x7ff00000)
       return y;
-    if (ABS(y) > 1.0e20) return (y>0)?0:1.0/ABS(x);
+    if (ABS(y) > 1.0e20) return (y>0)?0:1.0/0.0;
     k = checkint(y);
     if (k == -1)
       return y < 0 ? 1.0/x : x;
     else
-      return y < 0 ? 1.0/ABS(x) : 0.0;                               /* return 0 */
+      return y < 0 ? 1.0/0.0 : 0.0;                               /* return 0 */
   }
 
   qx = u.i[HIGH_HALF]&0x7fffffff;  /*   no sign   */