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a67894c505
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.
120 lines
3.1 KiB
C
120 lines
3.1 KiB
C
/* Complex tangent function for float.
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Copyright (C) 1997-2015 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <complex.h>
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#include <fenv.h>
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#include <math.h>
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#include <math_private.h>
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#include <float.h>
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__complex__ float
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__ctanf (__complex__ float x)
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{
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__complex__ float res;
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if (__glibc_unlikely (!isfinite (__real__ x) || !isfinite (__imag__ x)))
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{
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if (__isinf_nsf (__imag__ x))
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{
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__real__ res = __copysignf (0.0, __real__ x);
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__imag__ res = __copysignf (1.0, __imag__ x);
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}
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else if (__real__ x == 0.0)
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{
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res = x;
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}
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else
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{
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__real__ res = __nanf ("");
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__imag__ res = __nanf ("");
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if (__isinf_nsf (__real__ x))
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feraiseexcept (FE_INVALID);
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}
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}
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else
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{
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float sinrx, cosrx;
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float den;
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const int t = (int) ((FLT_MAX_EXP - 1) * M_LN2 / 2);
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/* tan(x+iy) = (sin(2x) + i*sinh(2y))/(cos(2x) + cosh(2y))
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= (sin(x)*cos(x) + i*sinh(y)*cosh(y)/(cos(x)^2 + sinh(y)^2). */
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if (__glibc_likely (fabsf (__real__ x) > FLT_MIN))
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{
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__sincosf (__real__ x, &sinrx, &cosrx);
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}
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else
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{
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sinrx = __real__ x;
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cosrx = 1.0f;
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}
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if (fabsf (__imag__ x) > t)
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{
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/* Avoid intermediate overflow when the real part of the
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result may be subnormal. Ignoring negligible terms, the
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imaginary part is +/- 1, the real part is
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sin(x)*cos(x)/sinh(y)^2 = 4*sin(x)*cos(x)/exp(2y). */
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float exp_2t = __ieee754_expf (2 * t);
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__imag__ res = __copysignf (1.0, __imag__ x);
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__real__ res = 4 * sinrx * cosrx;
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__imag__ x = fabsf (__imag__ x);
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__imag__ x -= t;
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__real__ res /= exp_2t;
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if (__imag__ x > t)
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{
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/* Underflow (original imaginary part of x has absolute
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value > 2t). */
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__real__ res /= exp_2t;
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}
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else
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__real__ res /= __ieee754_expf (2 * __imag__ x);
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}
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else
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{
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float sinhix, coshix;
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if (fabsf (__imag__ x) > FLT_MIN)
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{
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sinhix = __ieee754_sinhf (__imag__ x);
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coshix = __ieee754_coshf (__imag__ x);
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}
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else
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{
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sinhix = __imag__ x;
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coshix = 1.0f;
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}
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if (fabsf (sinhix) > fabsf (cosrx) * FLT_EPSILON)
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den = cosrx * cosrx + sinhix * sinhix;
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else
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den = cosrx * cosrx;
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__real__ res = sinrx * cosrx / den;
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__imag__ res = sinhix * coshix / den;
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}
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}
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return res;
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}
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#ifndef __ctanf
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weak_alias (__ctanf, ctanf)
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#endif
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