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a5721ebc68
glibc/sysdeps/x86_64/fpu
History
Joseph Myers a5721ebc68 Fix clog, clog10 inaccuracy (bug 19016). 
For arguments with X^2 + Y^2 close to 1, clog and clog10 avoid large
errors from log(hypot) by computing X^2 + Y^2 - 1 in a way that avoids
cancellation error and then using log1p.

However, the thresholds for using that approach still result in log
being used on argument as large as sqrt(13/16) > 0.9, leading to
significant errors, in some cases above the 9ulp maximum allowed in
glibc libm.  This patch arranges for the approach using log1p to be
used in any cases where |X|, |Y| < 1 and X^2 + Y^2 >= 0.5 (with the
existing allowance for cases where one of X and Y is very small),
adjusting the __x2y2m1 functions to work with the wider range of
inputs.  This way, log only gets used on arguments below sqrt(1/2) (or
substantially above 1), where the error involved is much less.

Tested for x86_64, x86, mips64 and powerpc.  For the ulps regeneration
I removed the existing clog and clog10 ulps before regenerating to
allow any reduced ulps to appear.  Tests added include those found by
random test generation to produce large ulps either before or after
the patch, and some found by trying inputs close to the (0.75, 0.5)
threshold where the potential errors from using log are largest.

	[BZ #19016]
	* sysdeps/generic/math_private.h (__x2y2m1f): Update comment to
	allow more cases with X^2 + Y^2 >= 0.5.
	* sysdeps/ieee754/dbl-64/x2y2m1.c (__x2y2m1): Likewise.  Add -1 as
	normal element in sum instead of special-casing based on values of
	arguments.
	* sysdeps/ieee754/dbl-64/x2y2m1f.c (__x2y2m1f): Update comment.
	* sysdeps/ieee754/ldbl-128/x2y2m1l.c (__x2y2m1l): Likewise.  Add
	-1 as normal element in sum instead of special-casing based on
	values of arguments.
	* sysdeps/ieee754/ldbl-128ibm/x2y2m1l.c (__x2y2m1l): Likewise.
	* sysdeps/ieee754/ldbl-96/x2y2m1.c [FLT_EVAL_METHOD != 0]
	(__x2y2m1): Update comment.
	* sysdeps/ieee754/ldbl-96/x2y2m1l.c (__x2y2m1l): Likewise.  Add -1
	as normal element in sum instead of special-casing based on values
	of arguments.
	* math/s_clog.c (__clog): Handle more cases using log1p without
	hypot.
	* math/s_clog10.c (__clog10): Likewise.
	* math/s_clog10f.c (__clog10f): Likewise.
	* math/s_clog10l.c (__clog10l): Likewise.
	* math/s_clogf.c (__clogf): Likewise.
	* math/s_clogl.c (__clogl): Likewise.
	* math/auto-libm-test-in: Add more tests of clog and clog10.
	* math/auto-libm-test-out: Regenerated.
	* sysdeps/i386/fpu/libm-test-ulps: Update.
	* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
2015-09-28 22:11:22 +00:00
..
multiarch Fix x86_64 fma4 pow inappropriate contraction (bug 19003). 2015-09-24 16:48:32 +00:00
dla.h Remove x86_64 __GNUC_PREREQ (4, 6) conditional. 2014-11-14 18:53:07 +00:00
e_acosl.c
e_atan2l.c
e_exp2l.S Refactor x86_64 libm code forcing underflow exceptions. 2015-09-24 22:25:30 +00:00
e_exp10l.S
e_expf.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
e_expl.S Refactor x86_64 libm code forcing underflow exceptions. 2015-09-24 22:25:30 +00:00
e_fmodl.S
e_ilogbl.S
e_log2l.S Fix log2 (1) in round-downward mode (bug 17042). 2014-06-10 12:07:15 +00:00
e_log10l.S Fix log10 (1) in round-downward mode (bug 16977). 2014-05-23 12:07:50 +00:00
e_logl.S Fix __ieee754_logl (-LDBL_MAX) in FE_DOWNWARD mode (bug 17022). 2014-06-18 12:32:01 +00:00
e_powl.S Fix pow missing underflows (bug 18825). 2015-09-25 22:29:10 +00:00
e_remainderl.S
e_scalbl.S Fix x86/x86_64 scalb (qNaN, -Inf) (bug 16783). 2015-02-24 17:30:02 +00:00
e_sqrt.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
e_sqrtf.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
e_sqrtl.c
fclrexcpt.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
fedisblxcpt.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
feenablxcpt.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
fegetenv.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
fegetexcept.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
fegetround.c Fix libm fegetround namespace (bug 17748). 2015-01-02 20:44:42 +00:00
feholdexcpt.c Fix libm feholdexcept namespace (bug 17748). 2015-01-05 23:06:14 +00:00
fesetenv.c Fix libm fesetenv namespace (bug 17748). 2015-01-06 23:36:20 +00:00
fesetround.c Fix libm fesetround namespace (bug 17748). 2015-01-07 00:41:23 +00:00
feupdateenv.c Fix libm feupdateenv namespace (bug 17748). 2015-01-07 19:01:20 +00:00
fgetexcptflg.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
fraiseexcpt.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
fsetexcptflg.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
ftestexcept.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
Implies
k_rem_pio2l.c
libm-test-ulps Fix clog, clog10 inaccuracy (bug 19016). 2015-09-28 22:11:22 +00:00
Makefile Update libmvec multiarch functions for <cpu-features.h> 2015-08-13 03:41:47 -07:00
math_ldbl.h
math_private.h
math-tests-arch.h Update libmvec multiarch functions for <cpu-features.h> 2015-08-13 03:41:47 -07:00
printf_fphex.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_atanl.c
s_ceill.S
s_copysign.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_copysignf.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_copysignl.S
s_cosf.S Align stack to 16 bytes when calling __errno_location 2015-08-05 08:36:27 -07:00
s_expm1l.S
s_fabs.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fabsf.c Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fabsl.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fdiml.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_finitel.S
s_floorl.S
s_fmax.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fmaxf.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fmaxl.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fmin.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fminf.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fminl.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_fpclassifyl.c
s_isinfl.c
s_isnanl.c
s_llrint.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_llrintf.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_llrintl.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_log1pl.S Set errno for log1p on pole/domain error. 2015-04-13 21:19:27 +02:00
s_logbl.c
s_lrint.S
s_lrintf.S
s_lrintl.S
s_nearbyintl.S
s_nextafterl.c
s_nexttoward.c
s_nexttowardf.c
s_rintl.c
s_scalbnl.S Make scalbn set errno (bug 6803). 2015-09-16 21:11:00 +00:00
s_signbit.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_signbitf.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
s_significandl.c
s_sincosf.S Align stack to 16 bytes when calling __errno_location 2015-08-05 08:36:27 -07:00
s_sinf.S Align stack to 16 bytes when calling __errno_location 2015-08-05 08:36:27 -07:00
s_truncl.S Update copyright dates with scripts/update-copyrights. 2015-01-02 16:29:47 +00:00
svml_d_cos2_core.S Combination of data tables for x86_64 vector functions sin, cos and sincos. 2015-06-23 19:21:50 +03:00
svml_d_cos4_core_avx.S Start of series of patches with x86_64 vector math functions. 2015-06-09 14:25:49 +03:00
svml_d_cos4_core.S Combination of data tables for x86_64 vector functions sin, cos and sincos. 2015-06-23 19:21:50 +03:00
svml_d_cos8_core.S Combination of data tables for x86_64 vector functions sin, cos and sincos. 2015-06-23 19:21:50 +03:00
svml_d_exp2_core.S Vector exp for x86_64 and tests. 2015-06-17 15:58:05 +03:00
svml_d_exp4_core_avx.S Vector exp for x86_64 and tests. 2015-06-17 15:58:05 +03:00
svml_d_exp4_core.S Vector exp for x86_64 and tests. 2015-06-17 15:58:05 +03:00
svml_d_exp8_core.S Vector exp for x86_64 and tests. 2015-06-17 15:58:05 +03:00
svml_d_exp_data.h Vector exp for x86_64 and tests. 2015-06-17 15:58:05 +03:00
svml_d_exp_data.S Vector exp for x86_64 and tests. 2015-06-17 15:58:05 +03:00
svml_d_log2_core.S Vector log for x86_64 and tests. 2015-06-17 15:38:29 +03:00
svml_d_log4_core_avx.S Vector log for x86_64 and tests. 2015-06-17 15:38:29 +03:00
svml_d_log4_core.S Vector log for x86_64 and tests. 2015-06-17 15:38:29 +03:00
svml_d_log8_core.S Vector log for x86_64 and tests. 2015-06-17 15:38:29 +03:00
svml_d_log_data.h Vector log for x86_64 and tests. 2015-06-17 15:38:29 +03:00
svml_d_log_data.S Vector log for x86_64 and tests. 2015-06-17 15:38:29 +03:00
svml_d_pow2_core.S Vector pow for x86_64 and tests. 2015-06-17 16:22:26 +03:00
svml_d_pow4_core_avx.S Vector pow for x86_64 and tests. 2015-06-17 16:22:26 +03:00
svml_d_pow4_core.S Vector pow for x86_64 and tests. 2015-06-17 16:22:26 +03:00
svml_d_pow8_core.S Vector pow for x86_64 and tests. 2015-06-17 16:22:26 +03:00
svml_d_pow_data.h Vector pow for x86_64 and tests. 2015-06-17 16:22:26 +03:00
svml_d_pow_data.S Vector pow for x86_64 and tests. 2015-06-17 16:22:26 +03:00
svml_d_sin2_core.S Vector sin for x86_64 and tests. 2015-06-11 17:12:38 +03:00
svml_d_sin4_core_avx.S Vector sin for x86_64 and tests. 2015-06-11 17:12:38 +03:00
svml_d_sin4_core.S Vector sin for x86_64 and tests. 2015-06-11 17:12:38 +03:00
svml_d_sin8_core.S Vector sin for x86_64 and tests. 2015-06-11 17:12:38 +03:00
svml_d_sincos2_core.S Vector sincos for x86_64 and tests. 2015-06-18 17:55:55 +03:00
svml_d_sincos4_core_avx.S Vector sincos for x86_64 and tests. 2015-06-18 17:55:55 +03:00
svml_d_sincos4_core.S Vector sincos for x86_64 and tests. 2015-06-18 17:55:55 +03:00
svml_d_sincos8_core.S Vector sincos for x86_64 and tests. 2015-06-18 17:55:55 +03:00
svml_d_trig_data.h Combination of data tables for x86_64 vector functions sin, cos and sincos. 2015-06-23 19:21:50 +03:00
svml_d_trig_data.S Combination of data tables for x86_64 vector functions sin, cos and sincos. 2015-06-23 19:21:50 +03:00
svml_d_wrapper_impl.h Fixed several libmvec bugs found during testing on KNL hardware. 2015-07-24 14:47:23 +03:00
svml_s_cosf4_core.S Vector cosf for x86_64. 2015-06-09 18:29:47 +03:00
svml_s_cosf8_core_avx.S Vector cosf for x86_64. 2015-06-09 18:29:47 +03:00
svml_s_cosf8_core.S Vector cosf for x86_64. 2015-06-09 18:29:47 +03:00
svml_s_cosf16_core.S Vector cosf for x86_64. 2015-06-09 18:29:47 +03:00
svml_s_expf4_core.S Vector expf for x86_64 and tests. 2015-06-17 16:10:51 +03:00
svml_s_expf8_core_avx.S Vector expf for x86_64 and tests. 2015-06-17 16:10:51 +03:00
svml_s_expf8_core.S Vector expf for x86_64 and tests. 2015-06-17 16:10:51 +03:00
svml_s_expf16_core.S Vector expf for x86_64 and tests. 2015-06-17 16:10:51 +03:00
svml_s_expf_data.h Vector expf for x86_64 and tests. 2015-06-17 16:10:51 +03:00
svml_s_expf_data.S Vector expf for x86_64 and tests. 2015-06-17 16:10:51 +03:00
svml_s_logf4_core.S Vector logf for x86_64 and tests. 2015-06-17 15:53:00 +03:00
svml_s_logf8_core_avx.S Vector logf for x86_64 and tests. 2015-06-17 15:53:00 +03:00
svml_s_logf8_core.S Vector logf for x86_64 and tests. 2015-06-17 15:53:00 +03:00
svml_s_logf16_core.S Vector logf for x86_64 and tests. 2015-06-17 15:53:00 +03:00
svml_s_logf_data.h Vector logf for x86_64 and tests. 2015-06-17 15:53:00 +03:00
svml_s_logf_data.S Vector logf for x86_64 and tests. 2015-06-17 15:53:00 +03:00
svml_s_powf4_core.S Vector powf for x86_64 and tests. 2015-06-18 17:04:07 +03:00
svml_s_powf8_core_avx.S Vector powf for x86_64 and tests. 2015-06-18 17:04:07 +03:00
svml_s_powf8_core.S Vector powf for x86_64 and tests. 2015-06-18 17:04:07 +03:00
svml_s_powf16_core.S Vector powf for x86_64 and tests. 2015-06-18 17:04:07 +03:00
svml_s_powf_data.h Vector powf for x86_64 and tests. 2015-06-18 17:04:07 +03:00
svml_s_powf_data.S Vector powf for x86_64 and tests. 2015-06-18 17:04:07 +03:00
svml_s_sincosf4_core.S Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
svml_s_sincosf8_core_avx.S Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
svml_s_sincosf8_core.S Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
svml_s_sincosf16_core.S Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
svml_s_sinf4_core.S Vector sinf for x86_64 and tests. 2015-06-15 15:06:53 +03:00
svml_s_sinf8_core_avx.S Vector sinf for x86_64 and tests. 2015-06-15 15:06:53 +03:00
svml_s_sinf8_core.S Vector sinf for x86_64 and tests. 2015-06-15 15:06:53 +03:00
svml_s_sinf16_core.S Vector sinf for x86_64 and tests. 2015-06-15 15:06:53 +03:00
svml_s_trig_data.h Combination of data tables for x86_64 vector functions sinf, cosf and sincosf. 2015-06-24 17:44:35 +03:00
svml_s_trig_data.S Combination of data tables for x86_64 vector functions sinf, cosf and sincosf. 2015-06-24 17:44:35 +03:00
svml_s_wrapper_impl.h Fixed several libmvec bugs found during testing on KNL hardware. 2015-07-24 14:47:23 +03:00
test-double-vlen2-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-double-vlen2.c Vector sincos for x86_64 and tests. 2015-06-18 17:55:55 +03:00
test-double-vlen4-avx2-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-double-vlen4-avx2.c Vector sincos for x86_64 and tests. 2015-06-18 17:55:55 +03:00
test-double-vlen4-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-double-vlen4.c Added runtime check for AVX vector math tests. 2015-07-29 19:47:29 +03:00
test-double-vlen8-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-double-vlen8.c Vector sincos for x86_64 and tests. 2015-06-18 17:55:55 +03:00
test-float-vlen4-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-float-vlen4.c Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
test-float-vlen8-avx2-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-float-vlen8-avx2.c Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
test-float-vlen8-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-float-vlen8.c Added runtime check for AVX vector math tests. 2015-07-29 19:47:29 +03:00
test-float-vlen16-wrappers.c Refactor libm tests. 2015-06-24 23:27:18 +00:00
test-float-vlen16.c Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
Versions Vector sincosf for x86_64 and tests. 2015-06-18 20:11:27 +03:00
x86_64-math-asm.h Fix pow missing underflows (bug 18825). 2015-09-25 22:29:10 +00:00