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| author | Joseph Myers <joseph@codesourcery.com> | 2015-05-15 00:16:10 +0000 |
|---|---|---|
| committer | Joseph Myers <joseph@codesourcery.com> | 2015-05-15 00:16:10 +0000 |
| commit | fbc68f03b0e56db6a07d789fd403eb79d726fe96 (patch) | |
| tree | a39460f48cef09b5e9577c38b9b061ddfb335fab /NEWS | |
| parent | 9a71f1fcf53615c00b5f9e5da4bba92bccb0efb4 (diff) | |
| download | glibc-fbc68f03b0e56db6a07d789fd403eb79d726fe96.zip glibc-fbc68f03b0e56db6a07d789fd403eb79d726fe96.tar.gz glibc-fbc68f03b0e56db6a07d789fd403eb79d726fe96.tar.bz2 | |
Fix erfcf spurious underflows (bug 18217).
The flt-32 implementation of erfcf produces spurious underflow
exceptions for some arguments close to 0, because of calculations
squaring the argument and then multiplying by small constants. This
patch fixes this by adjusting the threshold for arguments for which
the result is so close to 1 that 1 - x will give the right result from
2**-56 to 2**-26. (If 1 - x * 2/sqrt(pi) were used, the errors would be
on the order of x^3 and a much larger threshold could be used.)
Tested for x86_64 and x86.
[BZ #18217]
* sysdeps/ieee754/flt-32/s_erff.c (__erfcf): Use 2**-26 not 2**-56
as threshold for returning 1 - x.
* math/auto-libm-test-in: Add more tests of erfc.
* math/auto-libm-test-out: Regenerated.
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 4 |
1 files changed, 2 insertions, 2 deletions
@@ -16,8 +16,8 @@ Version 2.22 17964, 17965, 17967, 17969, 17978, 17987, 17991, 17996, 17998, 17999, 18007, 18019, 18020, 18029, 18030, 18032, 18036, 18038, 18039, 18042, 18043, 18046, 18047, 18068, 18080, 18093, 18100, 18104, 18110, 18111, - 18125, 18128, 18138, 18185, 18196, 18197, 18206, 18210, 18211, 18247, - 18287, 18319, 18333, 18346, 18397, 18409. + 18125, 18128, 18138, 18185, 18196, 18197, 18206, 18210, 18211, 18217, + 18247, 18287, 18319, 18333, 18346, 18397, 18409. * Cache information can be queried via sysconf() function on s390 e.g. with _SC_LEVEL1_ICACHE_SIZE as argument. |