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2f3184451d
sysdeps/ieee754/ldbl-128ibm has its own versions of cprojl, ctanhl and
ctanl.
Having its own versions, where otherwise the math/ copies are
generally used for all floating-point formats, means they are liable
to get out of sync and not benefit from bug fixes to the generic
versions. The substantive differences (not arising from getting out
of sync and slightly different fixes for the same issues) are: long
double compat handling (also done in the ldbl-opt versions, so doesn't
require special versions for ldbl-128ibm); handling of LDBL_EPSILON
(conditionally undefined and redefined in other math/ implementations,
so doesn't justify a special version), and:
/* __gcc_qmul does not respect -0.0 so we need the following fixup. */
if ((__real__ res == 0.0L) && (__real__ x == 0.0L))
__real__ res = __real__ x;
if ((__real__ res == 0.0L) && (__imag__ x == 0.0L))
__imag__ res = __imag__ x;
But if that statement about __gcc_qmul was ever true for an old
version of that libgcc function, it's not the case for any GCC version
now supported to build glibc; there's explicit logic early in that
function (and similarly in __gcc_qdiv) to return an appropriately
signed zero if the product of the high parts is zero. So this patch
adds the special LDBL_EPSILON handling to the generic functions and
removes the ldbl-128ibm versions.
Tested for powerpc32 (compared test-ldouble.out before and after the
changes; there are slight changes to results for ctanl / ctanhl,
arising from divergence of the implementations, but nothing that
affects the overall nature of the issues shown by the testsuite, and
in particular nothing related to signs of zero resutls).
* math/s_ctanhl.c [LDBL_MANT_DIG == 106] (LDBL_EPSILON): Undefine
and redefine.
* math/s_ctanl.c [LDBL_MANT_DIG == 106] (LDBL_EPSILON): Undefine
and redefine.
* sysdeps/ieee754/ldbl-128ibm/s_cprojl.c: Remove file.
* sysdeps/ieee754/ldbl-128ibm/s_ctanhl.c: Likewise.
* sysdeps/ieee754/ldbl-128ibm/s_ctanl.c: Likewise.
126 lines
3.3 KiB
C
126 lines
3.3 KiB
C
/* Complex tangent function for long double.
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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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/* To avoid spurious underflows, use this definition to treat IBM long
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double as approximating an IEEE-style format. */
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#if LDBL_MANT_DIG == 106
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# undef LDBL_EPSILON
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# define LDBL_EPSILON 0x1p-106L
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#endif
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__complex__ long double
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__ctanl (__complex__ long double x)
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{
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__complex__ long double res;
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if (__glibc_unlikely (!isfinite (__real__ x) || !isfinite (__imag__ x)))
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{
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if (__isinf_nsl (__imag__ x))
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{
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__real__ res = __copysignl (0.0, __real__ x);
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__imag__ res = __copysignl (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 = __nanl ("");
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__imag__ res = __nanl ("");
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if (__isinf_nsl (__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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long double sinrx, cosrx;
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long double den;
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const int t = (int) ((LDBL_MAX_EXP - 1) * M_LN2l / 2);
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int rcls = fpclassify (__real__ x);
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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 (rcls != FP_SUBNORMAL))
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{
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__sincosl (__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 = 1.0;
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}
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if (fabsl (__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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long double exp_2t = __ieee754_expl (2 * t);
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__imag__ res = __copysignl (1.0, __imag__ x);
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__real__ res = 4 * sinrx * cosrx;
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__imag__ x = fabsl (__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_expl (2 * __imag__ x);
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}
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else
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{
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long double sinhix, coshix;
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if (fabsl (__imag__ x) > LDBL_MIN)
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{
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sinhix = __ieee754_sinhl (__imag__ x);
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coshix = __ieee754_coshl (__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 = 1.0L;
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}
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if (fabsl (sinhix) > fabsl (cosrx) * LDBL_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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weak_alias (__ctanl, ctanl)
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