1 /* Return arc tangent of complex float 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 #include "math_private.h" 25 26 27 __complex__ float 28 __catanf (__complex__ float x) 29 { 30 __complex__ float res; 31 int rcls = fpclassify (__real__ x); 32 int icls = fpclassify (__imag__ x); 33 34 if (rcls <= FP_INFINITE || icls <= FP_INFINITE) 35 { 36 if (rcls == FP_INFINITE) 37 { 38 __real__ res = __copysignf (M_PI_2, __real__ x); 39 __imag__ res = __copysignf (0.0, __imag__ x); 40 } 41 else if (icls == FP_INFINITE) 42 { 43 if (rcls >= FP_ZERO) 44 __real__ res = __copysignf (M_PI_2, __real__ x); 45 else 46 __real__ res = __nanf (""); 47 __imag__ res = __copysignf (0.0, __imag__ x); 48 } 49 else if (icls == FP_ZERO || icls == FP_INFINITE) 50 { 51 __real__ res = __nanf (""); 52 __imag__ res = __copysignf (0.0, __imag__ x); 53 } 54 else 55 { 56 __real__ res = __nanf (""); 57 __imag__ res = __nanf (""); 58 } 59 } 60 else if (rcls == FP_ZERO && icls == FP_ZERO) 61 { 62 res = x; 63 } 64 else 65 { 66 float r2, num, den; 67 68 r2 = __real__ x * __real__ x; 69 70 den = 1 - r2 - __imag__ x * __imag__ x; 71 72 __real__ res = 0.5 * __ieee754_atan2f (2.0 * __real__ x, den); 73 74 num = __imag__ x + 1.0; 75 num = r2 + num * num; 76 77 den = __imag__ x - 1.0; 78 den = r2 + den * den; 79 80 __imag__ res = 0.25 * __ieee754_logf (num / den); 81 } 82 83 return res; 84 } 85 #ifndef __catanf 86 weak_alias (__catanf, catanf) 87 #endif 88