1 /* Return arc tangent of complex double value.
2 Copyright (C) 1997-2013 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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.
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.
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <http://www.gnu.org/licenses/>. */
22 #include <math_private.h>
26 __catan (__complex__ double x)
28 __complex__ double res;
29 int rcls = fpclassify (__real__ x);
30 int icls = fpclassify (__imag__ x);
32 if (__builtin_expect (rcls <= FP_INFINITE || icls <= FP_INFINITE, 0))
34 if (rcls == FP_INFINITE)
36 __real__ res = __copysign (M_PI_2, __real__ x);
37 __imag__ res = __copysign (0.0, __imag__ x);
39 else if (icls == FP_INFINITE)
42 __real__ res = __copysign (M_PI_2, __real__ x);
44 __real__ res = __nan ("");
45 __imag__ res = __copysign (0.0, __imag__ x);
47 else if (icls == FP_ZERO || icls == FP_INFINITE)
49 __real__ res = __nan ("");
50 __imag__ res = __copysign (0.0, __imag__ x);
54 __real__ res = __nan ("");
55 __imag__ res = __nan ("");
58 else if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0))
64 double r2, num, den, f;
66 r2 = __real__ x * __real__ x;
68 den = 1 - r2 - __imag__ x * __imag__ x;
70 __real__ res = 0.5 * __ieee754_atan2 (2.0 * __real__ x, den);
72 num = __imag__ x + 1.0;
75 den = __imag__ x - 1.0;
80 __imag__ res = 0.25 * __ieee754_log (f);
83 num = 4.0 * __imag__ x;
84 __imag__ res = 0.25 * __log1p (num / den);
87 if (fabs (__real__ res) < DBL_MIN)
89 volatile double force_underflow = __real__ res * __real__ res;
90 (void) force_underflow;
92 if (fabs (__imag__ res) < DBL_MIN)
94 volatile double force_underflow = __imag__ res * __imag__ res;
95 (void) force_underflow;
101 weak_alias (__catan, catan)
102 #ifdef NO_LONG_DOUBLE
103 strong_alias (__catan, __catanl)
104 weak_alias (__catan, catanl)