1 /* Return arc hyperbole cosine for double value. 2 Copyright (C) 1997 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997. 5 6 The GNU C Library is free software; you can redistribute it and/or 7 modify it under the terms of the GNU Lesser General Public 8 License as published by the Free Software Foundation; either 9 version 2.1 of the License, or (at your option) any later version. 10 11 The GNU C Library is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 Lesser General Public License for more details. 15 16 You should have received a copy of the GNU Lesser General Public 17 License along with the GNU C Library; if not, write to the Free 18 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 19 02111-1307 USA. */ 20 21 #include <complex.h> 22 #include <math.h> 23 24 25 __complex__ double 26 __cacosh (__complex__ double x) 27 { 28 __complex__ double res; 29 int rcls = fpclassify (__real__ x); 30 int icls = fpclassify (__imag__ x); 31 32 if (rcls <= FP_INFINITE || icls <= FP_INFINITE) 33 { 34 if (icls == FP_INFINITE) 35 { 36 __real__ res = HUGE_VAL; 37 38 if (rcls == FP_NAN) 39 __imag__ res = nan (""); 40 else 41 __imag__ res = copysign ((rcls == FP_INFINITE 42 ? (__real__ x < 0.0 43 ? M_PI - M_PI_4 : M_PI_4) 44 : M_PI_2), __imag__ x); 45 } 46 else if (rcls == FP_INFINITE) 47 { 48 __real__ res = HUGE_VAL; 49 50 if (icls >= FP_ZERO) 51 __imag__ res = copysign (signbit (__real__ x) ? M_PI : 0.0, 52 __imag__ x); 53 else 54 __imag__ res = nan (""); 55 } 56 else 57 { 58 __real__ res = nan (""); 59 __imag__ res = nan (""); 60 } 61 } 62 else if (rcls == FP_ZERO && icls == FP_ZERO) 63 { 64 __real__ res = 0.0; 65 __imag__ res = copysign (M_PI_2, __imag__ x); 66 } 67 else 68 { 69 __complex__ double y; 70 71 __real__ y = (__real__ x - __imag__ x) * (__real__ x + __imag__ x) - 1.0; 72 __imag__ y = 2.0 * __real__ x * __imag__ x; 73 74 y = __csqrt (y); 75 76 __real__ y += __real__ x; 77 __imag__ y += __imag__ x; 78 79 res = __clog (y); 80 } 81 82 return res; 83 } 84 weak_alias (__cacosh, cacosh) 85 #ifdef NO_LONG_DOUBLE 86 strong_alias (__cacosh, __cacoshl) 87 weak_alias (__cacosh, cacoshl) 88 #endif 89