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| author | Joseph Myers <joseph@codesourcery.com> | 2014-04-02 17:41:02 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2014-04-02 17:41:02 +0000 |
| commit | a84e78c8b3c4de94b488fdc5321f71feeb99358f (patch) | |
| tree | b4e8a63fd2eb10f4598a5af855e6462a9b06767e /sysdeps/ieee754 | |
| parent | 6f05bafebac30a389807979f8efbb709f84b486f (diff) | |
| download | glibc-a84e78c8b3c4de94b488fdc5321f71feeb99358f.zip glibc-a84e78c8b3c4de94b488fdc5321f71feeb99358f.tar.gz glibc-a84e78c8b3c4de94b488fdc5321f71feeb99358f.tar.bz2 | |
Fix catan, catanh, __ieee754_logf in round-downward mode (bug 16799, bug 16800).
This patch fixes incorrect results from catan and catanh of certain
special inputs in round-downward mode (bug 16799), and incorrect
results of __ieee754_logf (+/-0) in round-downward mode (bug 16800)
that show up through catan/catanh when tested in all rounding modes,
but not directly in the testing for logf because the bug gets hidden
by the wrappers.
Both bugs involve a zero that should be +0 being -0 instead: one
computed as (1-x)*(1+x) in the catan/catanh case, and one as (x-x) in
the logf case. The fixes ensure positive zero is used. Testing of
catan and catanh in all rounding modes is duly enabled.
I expect there are various other bugs in special cases in __ieee754_*
functions that are normally hidden by the wrappers but would show up
for testing with -lieee (or in future with -fno-math-errno if we
replace -lieee and _LIB_VERSION with compile-time redirection to new
*_noerrno symbol names).
Tested x86_64 and x86 and ulps updated accordingly.
[BZ #16799]
[BZ #16800]
* math/s_catan.c (__catan): Avoid passing -0 denominator to atan2
with 0 numerator.
* math/s_catanf.c (__catanf): Likewise.
* math/s_catanh.c (__catanh): Likewise.
* math/s_catanhf.c (__catanhf): Likewise.
* math/s_catanhl.c (__catanhl): Likewise.
* math/s_catanl.c (__catanl): Likewise.
* sysdeps/ieee754/flt-32/e_logf.c (__ieee754_logf): Always divide
by positive zero when computing -Inf result.
* math/libm-test.inc (catan_test): Use ALL_RM_TEST.
(catanh_test): Likewise.
* 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/flt-32/e_logf.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/sysdeps/ieee754/flt-32/e_logf.c b/sysdeps/ieee754/flt-32/e_logf.c index 7da6489..cf75e11 100644 --- a/sysdeps/ieee754/flt-32/e_logf.c +++ b/sysdeps/ieee754/flt-32/e_logf.c @@ -41,7 +41,7 @@ __ieee754_logf(float x) k=0; if (ix < 0x00800000) { /* x < 2**-126 */ if (__builtin_expect((ix&0x7fffffff)==0, 0)) - return -two25/(x-x); /* log(+-0)=-inf */ + return -two25/zero; /* log(+-0)=-inf */ if (__builtin_expect(ix<0, 0)) return (x-x)/(x-x); /* log(-#) = NaN */ k -= 25; x *= two25; /* subnormal number, scale up x */ |