1 /* Compute projection of complex long double value to Riemann sphere. 2 Copyright (C) 1997, 1999 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__ long double 26 __cprojl (__complex__ long double x) 27 { 28 __complex__ long double res; 29 30 if (isnan (__real__ x) && isnan (__imag__ x)) 31 return x; 32 else if (!isfinite (__real__ x) || !isfinite (__imag__ x)) 33 { 34 __real__ res = INFINITY; 35 __imag__ res = copysignl (0.0, __imag__ x); 36 } 37 else 38 { 39 long double den = (__real__ x * __real__ x + __imag__ x * __imag__ x 40 + 1.0); 41 42 __real__ res = (2.0 * __real__ x) / den; 43 __imag__ res = (2.0 * __imag__ x) / den; 44 } 45 46 return res; 47 } 48 weak_alias (__cprojl, cprojl) 49