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| author | Joseph Myers <joseph@codesourcery.com> | 2014-05-23 12:07:50 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2014-05-23 12:07:50 +0000 |
| commit | b72592e75fdecb34e2ac5f931730409a1fb68e8a (patch) | |
| tree | 9a7f71aecd06da02f507abf536a72a1bcbd69209 /sysdeps/ieee754 | |
| parent | 2302d679ce8b36854022207b58e554b3e89dd8c7 (diff) | |
| download | glibc-b72592e75fdecb34e2ac5f931730409a1fb68e8a.zip glibc-b72592e75fdecb34e2ac5f931730409a1fb68e8a.tar.gz glibc-b72592e75fdecb34e2ac5f931730409a1fb68e8a.tar.bz2 | |
Fix log10 (1) in round-downward mode (bug 16977).
As with various other issues of this kind, bug 16977 is log10 (1)
wrongly returning -0 rather than +0 in round-downward mode because of
an implementation effectively in terms of log1p (x - 1). This patch
fixes the issue in the same way used for log.
Tested x86_64 and x86 and ulps updated accordingly. Also tested for
mips64 to confirm a fix was needed for ldbl-128 and to validate that
fix (also applied to ldbl-128ibm since that version of logl is
essentially the same as the ldbl-128 one).
[BZ #16977]
* sysdeps/i386/fpu/e_log10.S (__ieee754_log10): Take absolute
value when x - 1 is zero.
* sysdeps/i386/fpu/e_log10f.S (__ieee754_log10f): Likewise.
* sysdeps/i386/fpu/e_log10l.S (__ieee754_log10l): Likewise.
* sysdeps/ieee754/ldbl-128/e_log10l.c (__ieee754_log10l): Return
0.0L for an argument of 1.0L.
* sysdeps/ieee754/ldbl-128ibm/e_log10l.c (__ieee754_log10l):
Likewise.
* sysdeps/x86_64/fpu/e_log10l.S (__ieee754_log10l): Take absolute
value when x - 1 is zero.
* math/libm-test.inc (log10_test): Use ALL_RM_TEST.
* sysdeps/i386/fpu/libm-test-ulps: Update.
* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
Diffstat (limited to 'sysdeps/ieee754')
| -rw-r--r-- | sysdeps/ieee754/ldbl-128/e_log10l.c | 3 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/e_log10l.c | 3 |
2 files changed, 6 insertions, 0 deletions
diff --git a/sysdeps/ieee754/ldbl-128/e_log10l.c b/sysdeps/ieee754/ldbl-128/e_log10l.c index b403f81..618255f 100644 --- a/sysdeps/ieee754/ldbl-128/e_log10l.c +++ b/sysdeps/ieee754/ldbl-128/e_log10l.c @@ -193,6 +193,9 @@ __ieee754_log10l (long double x) if (hx >= 0x7fff000000000000LL) return (x + x); + if (x == 1.0L) + return 0.0L; + /* separate mantissa from exponent */ /* Note, frexp is used so that denormal numbers diff --git a/sysdeps/ieee754/ldbl-128ibm/e_log10l.c b/sysdeps/ieee754/ldbl-128ibm/e_log10l.c index 1a6a4a0..7477791 100644 --- a/sysdeps/ieee754/ldbl-128ibm/e_log10l.c +++ b/sysdeps/ieee754/ldbl-128ibm/e_log10l.c @@ -195,6 +195,9 @@ __ieee754_log10l (long double x) if (hx >= 0x7ff0000000000000LL) return (x + x); + if (x == 1.0L) + return 0.0L; + /* separate mantissa from exponent */ /* Note, frexp is used so that denormal numbers |