/* Return arc tangent of complex double value. Copyright (C) 1997 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 <complex.h> #include <math.h> #include <math_private.h> __complex__ double __catan (__complex__ double x) { __complex__ double res; int rcls = fpclassify (__real__ x); int icls = fpclassify (__imag__ x); if (rcls <= FP_INFINITE || icls <= FP_INFINITE) { if (rcls == FP_INFINITE) { __real__ res = __copysign (M_PI_2, __real__ x); __imag__ res = __copysign (0.0, __imag__ x); } else if (icls == FP_INFINITE) { if (rcls >= FP_ZERO) __real__ res = __copysign (M_PI_2, __real__ x); else __real__ res = __nan (""); __imag__ res = __copysign (0.0, __imag__ x); } else if (icls == FP_ZERO || icls == FP_INFINITE) { __real__ res = __nan (""); __imag__ res = __copysign (0.0, __imag__ x); } else { __real__ res = __nan (""); __imag__ res = __nan (""); } } else if (rcls == FP_ZERO && icls == FP_ZERO) { res = x; } else { double r2, num, den; r2 = __real__ x * __real__ x; den = 1 - r2 - __imag__ x * __imag__ x; __real__ res = 0.5 * __ieee754_atan2 (2.0 * __real__ x, den); num = __imag__ x + 1.0; num = r2 + num * num; den = __imag__ x - 1.0; den = r2 + den * den; __imag__ res = 0.25 * __ieee754_log (num / den); } return res; } weak_alias (__catan, catan) #ifdef NO_LONG_DOUBLE strong_alias (__catan, __catanl) weak_alias (__catan, catanl) #endif