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| author | Siddhesh Poyarekar <siddhesh@sourceware.org> | 2016-07-18 22:33:09 +0530 |
|---|---|---|
| committer | Siddhesh Poyarekar <siddhesh@sourceware.org> | 2016-07-18 22:33:09 +0530 |
| commit | cbf88869edced4b23d792d95a8626e35b831df35 (patch) | |
| tree | b1ed5b36db2734e3dc0d4bcb4b6051630f7cbd0d /sysdeps | |
| parent | 2413e73c32fc36470885ae548631e081d66f4201 (diff) | |
| download | glibc-cbf88869edced4b23d792d95a8626e35b831df35.tar glibc-cbf88869edced4b23d792d95a8626e35b831df35.tar.gz glibc-cbf88869edced4b23d792d95a8626e35b831df35.tar.bz2 glibc-cbf88869edced4b23d792d95a8626e35b831df35.zip | |
Fix cos computation for multiple precision fallback (bz #20357)
During the sincos consolidation I made two mistakes, one was a logical
error due to which cos(0x1.8475e5afd4481p+0) returned
sin(0x1.8475e5afd4481p+0) instead.
The second issue was an error in negating inputs for the correct
quadrants for sine. I could not find a suitable test case for this
despite running a program to search for such an input for a couple of
hours.
Following patch fixes both issues. Tested on x86_64. Thanks to Matt
Clay for identifying the issue.
[BZ #20357]
* sysdeps/ieee754/dbl-64/s_sin.c (sloww): Fix up condition
to call __mpsin/__mpcos and to negate values.
* math/auto-libm-test-in: Add test.
* math/auto-libm-test-out: Regenerate.
Diffstat (limited to 'sysdeps')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/s_sin.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/sysdeps/ieee754/dbl-64/s_sin.c b/sysdeps/ieee754/dbl-64/s_sin.c index ca2532fb63..7c9a07990f 100644 --- a/sysdeps/ieee754/dbl-64/s_sin.c +++ b/sysdeps/ieee754/dbl-64/s_sin.c @@ -803,7 +803,7 @@ sloww (double x, double dx, double orig, int k) a = t - y; da = ((t - a) - y) + da; - if (n == 2 || n == 1) + if (n & 2) { a = -a; da = -da; @@ -817,7 +817,7 @@ sloww (double x, double dx, double orig, int k) if (w[0] == w[0] + cor) return (a > 0) ? w[0] : -w[0]; - return (n & 1) ? __mpcos (orig, 0, true) : __mpsin (orig, 0, true); + return k ? __mpcos (orig, 0, true) : __mpsin (orig, 0, true); } /***************************************************************************/ |