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0b87419b69
Similar to various other bugs in this area, ctan and ctanh can fail to raise the underflow exception for some cases of results that are tiny and inexact. This patch forces the exception in a similar way to previous fixes. Tested for x86_64 and x86. [BZ #18595] * math/s_ctan.c (__ctan): Force underflow exception for results whose real or imaginary part has small absolute value. * 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: Do not allow missing underflow for ctan and ctanh. Add more tests of ctan and ctanh.
130 lines
3.3 KiB
C
130 lines
3.3 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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if (fabsf (__real__ res) < FLT_MIN)
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{
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float force_underflow = __real__ res * __real__ res;
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math_force_eval (force_underflow);
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}
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if (fabsf (__imag__ res) < FLT_MIN)
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{
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float force_underflow = __imag__ res * __imag__ res;
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math_force_eval (force_underflow);
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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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