diff options
Diffstat (limited to 'sysdeps/generic/s_catan.c')
| -rw-r--r-- | sysdeps/generic/s_catan.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/sysdeps/generic/s_catan.c b/sysdeps/generic/s_catan.c new file mode 100644 index 0000000000..a3fc9ad3e8 --- /dev/null +++ b/sysdeps/generic/s_catan.c @@ -0,0 +1,89 @@ +/* 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 Library General Public License as + published by the Free Software Foundation; either version 2 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 + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. 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 |