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

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This commit is contained in:
Joseph Myers 2012-06-15 11:27:51 +00:00
parent 06c5abbdf8
commit 10285c2113
4 changed files with 13 additions and 3 deletions
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8
ChangeLog
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@ -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

2
NEWS
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@ -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:

2
math/libm-test.inc
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@ -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. */

4
sysdeps/ieee754/dbl-64/e_pow.c
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@ -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 */