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author | Joseph Myers <joseph@codesourcery.com> | 2015-06-24 21:04:51 +0000 |
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committer | Joseph Myers <joseph@codesourcery.com> | 2015-06-24 21:04:51 +0000 |
commit | a67894c505d44c3a5292804c37d318684d2be469 (patch) | |
tree | efd103776ffd4c9502fe2a1ae20dabde832d291b /math/s_ctanhl.c | |
parent | 010186901d16060a5d1178cc0f2f59199228b99a (diff) | |
download | glibc-a67894c505d44c3a5292804c37d318684d2be469.tar.gz glibc-a67894c505d44c3a5292804c37d318684d2be469.tar.xz glibc-a67894c505d44c3a5292804c37d318684d2be469.zip |
Fix cexp, ccos, ccosh, csin, csinh spurious underflows (bug 18594).
cexp, ccos, ccosh, csin and csinh have spurious underflows in cases where they compute sin of the smallest normal, that produces an underflow exception (depending on which sin implementation is in use) but the final result does not underflow. ctan and ctanh may also have such underflows, or they may be latent (the issue there is that e.g. ctan (DBL_MIN) should, rounded upwards, be the next double value above DBL_MIN, which under glibc's accuracy goals may not have an underflow exception, but the intermediate computation of sin (DBL_MIN) would legitimately underflow on before-rounding architectures). This patch fixes all those functions so they use plain comparisons (> DBL_MIN etc.) instead of comparing the result of fpclassify with FP_SUBNORMAL (in all these cases, we already know the number being compared is finite). Note that in the case of csin / csinf / csinl, there is no need for fabs calls in the comparison because the real part has already been reduced to its absolute value. As the patch fixes the failures that previously obstructed moving tests of cexp to use ALL_RM_TEST, those tests are moved to ALL_RM_TEST by the patch (two functions remain yet to be converted). Tested for x86_64 and x86 and ulps updated accordingly. [BZ #18594] * math/s_ccosh.c (__ccosh): Compare with least normal value instead of comparing class with FP_SUBNORMAL. * math/s_ccoshf.c (__ccoshf): Likewise. * math/s_ccoshl.c (__ccoshl): Likewise. * math/s_cexp.c (__cexp): Likewise. * math/s_cexpf.c (__cexpf): Likewise. * math/s_cexpl.c (__cexpl): Likewise. * math/s_csin.c (__csin): Likewise. * math/s_csinf.c (__csinf): Likewise. * math/s_csinh.c (__csinh): Likewise. * math/s_csinhf.c (__csinhf): Likewise. * math/s_csinhl.c (__csinhl): Likewise. * math/s_csinl.c (__csinl): Likewise. * math/s_ctan.c (__ctan): Likewise. * math/s_ctanf.c (__ctanf): Likewise. * math/s_ctanh.c (__ctanh): Likewise. * math/s_ctanhf.c (__ctanhf): Likewise. * math/s_ctanhl.c (__ctanhl): Likewise. * math/s_ctanl.c (__ctanl): Likewise. * math/auto-libm-test-in: Add more tests of ccos, ccosh, cexp, csin, csinh, ctan and ctanh. * math/auto-libm-test-out: Regenerated. * math/libm-test.inc (cexp_test): Use ALL_RM_TEST. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
Diffstat (limited to 'math/s_ctanhl.c')
-rw-r--r-- | math/s_ctanhl.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/math/s_ctanhl.c b/math/s_ctanhl.c index fa11db7ed4..6b9dfc5bb2 100644 --- a/math/s_ctanhl.c +++ b/math/s_ctanhl.c @@ -60,12 +60,11 @@ __ctanhl (__complex__ long double x) long double sinix, cosix; long double den; const int t = (int) ((LDBL_MAX_EXP - 1) * M_LN2l / 2); - int icls = fpclassify (__imag__ x); /* tanh(x+iy) = (sinh(2x) + i*sin(2y))/(cosh(2x) + cos(2y)) = (sinh(x)*cosh(x) + i*sin(y)*cos(y))/(sinh(x)^2 + cos(y)^2). */ - if (__glibc_likely (icls != FP_SUBNORMAL)) + if (__glibc_likely (fabsl (__imag__ x) > LDBL_MIN)) { __sincosl (__imag__ x, &sinix, &cosix); } |