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Fix clog / clog10 sign of zero result in round-downward mode (bug 16789).
This patch fixes bug 16789, incorrect sign of (real part) zero result from clog and clog10 in round-downward mode, arising from that real part being computed as 0 - 0. To ensure that an underflow exception occurred, the code used an underflowing value (the next term in the series for log1p) in arithmetic computing the real part of the result, yielding the problematic 0 - 0 computation in some cases even when the mathematical result would be small but positive. The patch changes this code to use the math_force_eval approach to ensuring that an underflowing computation actually occurs. Tests of clog and clog10 are enabled in all rounding modes. Tested x86_64 and x86 and ulps updated accordingly. [BZ #16789] * math/s_clog.c (__clog): Use math_force_eval to ensure underflow instead of using underflowing value in computing result. * 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/libm-test.inc (clog_test): Use ALL_RM_TEST. (clog10_test): Likewise. * sysdeps/i386/fpu/libm-test-ulps: Update. * sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
This commit is contained in:
Joseph Myers
parent
b0abbc2103
commit
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15
ChangeLog
15
ChangeLog
@ -1,3 +1,18 @@
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2014-04-02 Joseph Myers <joseph@codesourcery.com>
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[BZ #16789]
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* math/s_clog.c (__clog): Use math_force_eval to ensure underflow
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instead of using underflowing value in computing result.
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* math/s_clog10.c (__clog10): Likewise.
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* math/s_clog10f.c (__clog10f): Likewise.
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* math/s_clog10l.c (__clog10l): Likewise.
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* math/s_clogf.c (__clogf): Likewise.
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* math/s_clogl.c (__clogl): Likewise.
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* math/libm-test.inc (clog_test): Use ALL_RM_TEST.
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(clog10_test): Likewise.
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* sysdeps/i386/fpu/libm-test-ulps: Update.
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* sysdeps/x86_64/fpu/libm-test-ulps: Likewise.
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2014-04-02 Alan Modra <amodra@gmail.com>
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[BZ #16739]
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3
NEWS
3
NEWS
@ -13,7 +13,8 @@ Version 2.20
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16357, 16362, 16447, 16532, 16545, 16574, 16599, 16600, 16609, 16610,
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16611, 16613, 16623, 16632, 16634, 16639, 16642, 16648, 16649, 16670,
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16674, 16677, 16680, 16683, 16689, 16695, 16701, 16706, 16707, 16712,
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16713, 16714, 16731, 16739, 16743, 16758, 16759, 16760, 16770, 16786.
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16713, 16714, 16731, 16739, 16743, 16758, 16759, 16760, 16770, 16786,
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16789.
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* Running the testsuite no longer terminates as soon as a test fails.
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Instead, a file tests.sum (xtests.sum from "make xcheck") is generated,
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@ -6122,9 +6122,7 @@ static const struct test_c_c_data clog_test_data[] =
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static void
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clog_test (void)
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{
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START (clog, 0);
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RUN_TEST_LOOP_c_c (clog, clog_test_data, );
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END_COMPLEX;
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ALL_RM_TEST (clog, 0, clog_test_data, RUN_TEST_LOOP_c_c, END_COMPLEX);
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}
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@ -6184,9 +6182,7 @@ static const struct test_c_c_data clog10_test_data[] =
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static void
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clog10_test (void)
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{
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START (clog10, 0);
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RUN_TEST_LOOP_c_c (clog10, clog10_test_data, );
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END_COMPLEX;
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ALL_RM_TEST (clog10, 0, clog10_test_data, RUN_TEST_LOOP_c_c, END_COMPLEX);
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}
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@ -68,12 +68,9 @@ __clog (__complex__ double x)
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double absy2 = absy * absy;
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if (absy2 <= DBL_MIN * 2.0)
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{
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#if __FLT_EVAL_METHOD__ == 0
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__real__ result = absy2 / 2.0 - absy2 * absy2 / 4.0;
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#else
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volatile double force_underflow = absy2 * absy2 / 4.0;
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__real__ result = absy2 / 2.0 - force_underflow;
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#endif
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double force_underflow = absy2 * absy2;
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__real__ result = absy2 / 2.0;
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math_force_eval (force_underflow);
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}
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else
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__real__ result = __log1p (absy2) / 2.0;
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@ -74,12 +74,9 @@ __clog10 (__complex__ double x)
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double absy2 = absy * absy;
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if (absy2 <= DBL_MIN * 2.0 * M_LN10)
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{
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#if __FLT_EVAL_METHOD__ == 0
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__real__ result = (absy2 / 2.0 - absy2 * absy2 / 4.0) * M_LOG10E;
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#else
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volatile double force_underflow = absy2 * absy2 / 4.0;
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__real__ result = (absy2 / 2.0 - force_underflow) * M_LOG10E;
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#endif
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double force_underflow = absy2 * absy2;
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__real__ result = absy2 * (M_LOG10E / 2.0);
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math_force_eval (force_underflow);
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}
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else
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__real__ result = __log1p (absy2) * (M_LOG10E / 2.0);
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@ -74,14 +74,9 @@ __clog10f (__complex__ float x)
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float absy2 = absy * absy;
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if (absy2 <= FLT_MIN * 2.0f * (float) M_LN10)
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{
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#if __FLT_EVAL_METHOD__ == 0
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__real__ result
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= (absy2 / 2.0f - absy2 * absy2 / 4.0f) * (float) M_LOG10E;
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#else
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volatile float force_underflow = absy2 * absy2 / 4.0f;
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__real__ result
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= (absy2 / 2.0f - force_underflow) * (float) M_LOG10E;
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#endif
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float force_underflow = absy2 * absy2;
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__real__ result = absy2 * ((float) M_LOG10E / 2.0f);
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math_force_eval (force_underflow);
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}
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else
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__real__ result = __log1pf (absy2) * ((float) M_LOG10E / 2.0f);
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@ -80,8 +80,11 @@ __clog10l (__complex__ long double x)
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{
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long double absy2 = absy * absy;
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if (absy2 <= LDBL_MIN * 2.0L * M_LN10l)
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__real__ result
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= (absy2 / 2.0L - absy2 * absy2 / 4.0L) * M_LOG10El;
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{
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long double force_underflow = absy2 * absy2;
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__real__ result = absy2 * (M_LOG10El / 2.0);
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math_force_eval (force_underflow);
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}
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else
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__real__ result = __log1pl (absy2) * (M_LOG10El / 2.0L);
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}
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@ -68,12 +68,9 @@ __clogf (__complex__ float x)
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float absy2 = absy * absy;
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if (absy2 <= FLT_MIN * 2.0f)
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{
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#if __FLT_EVAL_METHOD__ == 0
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__real__ result = absy2 / 2.0f - absy2 * absy2 / 4.0f;
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#else
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volatile float force_underflow = absy2 * absy2 / 4.0f;
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__real__ result = absy2 / 2.0f - force_underflow;
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#endif
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float force_underflow = absy2 * absy2;
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__real__ result = absy2 / 2.0f;
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math_force_eval (force_underflow);
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}
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else
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__real__ result = __log1pf (absy2) / 2.0f;
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@ -74,7 +74,11 @@ __clogl (__complex__ long double x)
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{
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long double absy2 = absy * absy;
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if (absy2 <= LDBL_MIN * 2.0L)
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__real__ result = absy2 / 2.0L - absy2 * absy2 / 4.0L;
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{
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long double force_underflow = absy2 * absy2;
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__real__ result = absy2 / 2.0L;
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math_force_eval (force_underflow);
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}
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else
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__real__ result = __log1pl (absy2) / 2.0L;
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}
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@ -593,6 +593,102 @@ ifloat: 1
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog10_downward":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 4
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ldouble: 4
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Function: Imaginary part of "clog10_downward":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog10_towardzero":
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double: 2
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float: 1
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idouble: 2
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ifloat: 1
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ildouble: 4
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ldouble: 4
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Function: Imaginary part of "clog10_towardzero":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog10_upward":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 4
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ldouble: 4
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Function: Imaginary part of "clog10_upward":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog_downward":
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double: 2
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float: 1
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idouble: 2
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ifloat: 1
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ildouble: 2
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ldouble: 2
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Function: Imaginary part of "clog_downward":
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double: 1
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float: 1
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idouble: 1
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ifloat: 1
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ildouble: 1
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ldouble: 1
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Function: Real part of "clog_towardzero":
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double: 2
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float: 1
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idouble: 2
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ifloat: 1
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ildouble: 2
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ldouble: 2
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Function: Imaginary part of "clog_towardzero":
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double: 1
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float: 1
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idouble: 1
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ifloat: 1
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ildouble: 1
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ldouble: 1
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Function: Real part of "clog_upward":
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double: 1
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float: 1
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idouble: 1
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ifloat: 1
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ildouble: 2
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ldouble: 2
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Function: Imaginary part of "clog_upward":
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double: 1
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float: 1
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idouble: 1
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ifloat: 1
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ildouble: 1
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ldouble: 1
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Function: "cos":
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ildouble: 1
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ldouble: 1
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@ -624,6 +624,102 @@ ifloat: 1
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog10_downward":
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double: 3
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float: 3
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idouble: 3
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ifloat: 3
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ildouble: 4
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ldouble: 4
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Function: Imaginary part of "clog10_downward":
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double: 3
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float: 2
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idouble: 3
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog10_towardzero":
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double: 3
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float: 2
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idouble: 3
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ifloat: 2
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ildouble: 4
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ldouble: 4
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Function: Imaginary part of "clog10_towardzero":
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double: 3
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float: 2
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idouble: 3
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog10_upward":
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double: 4
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float: 3
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idouble: 4
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ifloat: 3
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ildouble: 4
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ldouble: 4
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Function: Imaginary part of "clog10_upward":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Real part of "clog_downward":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Imaginary part of "clog_downward":
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double: 1
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float: 2
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idouble: 1
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ifloat: 2
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ildouble: 1
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ldouble: 1
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Function: Real part of "clog_towardzero":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 2
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ldouble: 2
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Function: Imaginary part of "clog_towardzero":
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double: 1
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float: 2
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idouble: 1
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ifloat: 2
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ildouble: 1
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ldouble: 1
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Function: Real part of "clog_upward":
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double: 2
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float: 1
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idouble: 2
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ifloat: 1
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ildouble: 2
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ldouble: 2
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Function: Imaginary part of "clog_upward":
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double: 2
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float: 2
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idouble: 2
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ifloat: 2
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ildouble: 1
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ldouble: 1
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Function: "cos":
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ildouble: 1
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ldouble: 1
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