| /* Return arc hyperbole cosine for __float128 value. |
| Copyright (C) 1997, 1998, 2006 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, write to the Free |
| Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. */ |
| |
| #include "quadmath-imp.h" |
| |
| |
| __complex128 |
| cacoshq (__complex128 x) |
| { |
| __complex128 res; |
| int rcls = fpclassifyq (__real__ x); |
| int icls = fpclassifyq (__imag__ x); |
| |
| if (rcls <= QUADFP_INFINITE || icls <= QUADFP_INFINITE) |
| { |
| if (icls == QUADFP_INFINITE) |
| { |
| __real__ res = HUGE_VALQ; |
| |
| if (rcls == QUADFP_NAN) |
| __imag__ res = nanq (""); |
| else |
| __imag__ res = copysignq ((rcls == QUADFP_INFINITE |
| ? (__real__ x < 0.0 |
| ? M_PIq - M_PI_4q : M_PI_4q) |
| : M_PI_2q), __imag__ x); |
| } |
| else if (rcls == QUADFP_INFINITE) |
| { |
| __real__ res = HUGE_VALQ; |
| |
| if (icls >= QUADFP_ZERO) |
| __imag__ res = copysignq (signbitq (__real__ x) ? M_PIq : 0.0, |
| __imag__ x); |
| else |
| __imag__ res = nanq (""); |
| } |
| else |
| { |
| __real__ res = nanq (""); |
| __imag__ res = nanq (""); |
| } |
| } |
| else if (rcls == QUADFP_ZERO && icls == QUADFP_ZERO) |
| { |
| __real__ res = 0.0; |
| __imag__ res = copysignq (M_PI_2q, __imag__ x); |
| } |
| /* The factor 16 is just a guess. */ |
| else if (16.0Q * fabsq (__imag__ x) < fabsq (__real__ x)) |
| { |
| /* Kahan's formula which avoid cancellation through subtraction in |
| some cases. */ |
| res = 2.0Q * clogq (csqrtq ((x + 1.0Q) / 2.0Q) |
| + csqrtq ((x - 1.0Q) / 2.0Q)); |
| if (signbitq (__real__ res)) |
| __real__ res = 0.0Q; |
| } |
| else |
| { |
| __complex128 y; |
| |
| __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0; |
| __imag__ y = 2.0 * __real__ x * __imag__ x; |
| |
| y = csqrtq (y); |
| |
| if (signbitq (x)) |
| y = -y; |
| |
| __real__ y += __real__ x; |
| __imag__ y += __imag__ x; |
| |
| res = clogq (y); |
| } |
| |
| return res; |
| } |