96 lines
2.6 KiB
C
96 lines
2.6 KiB
C
/* Return arc hyperbole cosine for __float128 value.
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Copyright (C) 1997, 1998, 2006 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include "quadmath-imp.h"
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__complex128
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cacoshq (__complex128 x)
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{
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__complex128 res;
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int rcls = fpclassifyq (__real__ x);
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int icls = fpclassifyq (__imag__ x);
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if (rcls <= QUADFP_INFINITE || icls <= QUADFP_INFINITE)
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{
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if (icls == QUADFP_INFINITE)
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{
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__real__ res = HUGE_VALQ;
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if (rcls == QUADFP_NAN)
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__imag__ res = nanq ("");
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else
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__imag__ res = copysignq ((rcls == QUADFP_INFINITE
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? (__real__ x < 0.0
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? M_PIq - M_PI_4q : M_PI_4q)
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: M_PI_2q), __imag__ x);
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}
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else if (rcls == QUADFP_INFINITE)
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{
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__real__ res = HUGE_VALQ;
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if (icls >= QUADFP_ZERO)
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__imag__ res = copysignq (signbitq (__real__ x) ? M_PIq : 0.0,
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__imag__ x);
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else
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__imag__ res = nanq ("");
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}
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else
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{
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__real__ res = nanq ("");
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__imag__ res = nanq ("");
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}
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}
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else if (rcls == QUADFP_ZERO && icls == QUADFP_ZERO)
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{
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__real__ res = 0.0;
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__imag__ res = copysignq (M_PI_2q, __imag__ x);
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}
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/* The factor 16 is just a guess. */
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else if (16.0Q * fabsq (__imag__ x) < fabsq (__real__ x))
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{
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/* Kahan's formula which avoid cancellation through subtraction in
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some cases. */
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res = 2.0Q * clogq (csqrtq ((x + 1.0Q) / 2.0Q)
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+ csqrtq ((x - 1.0Q) / 2.0Q));
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if (signbit (__real__ res))
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__real__ res = 0.0Q;
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}
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else
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{
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__complex128 y;
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__real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0;
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__imag__ y = 2.0 * __real__ x * __imag__ x;
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y = csqrtq (y);
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if (signbitq (x))
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y = -y;
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__real__ y += __real__ x;
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__imag__ y += __imag__ x;
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res = clogq (y);
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}
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return res;
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}
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