1/* Return arc tangent of complex __float128 value.
2 Copyright (C) 1997, 1998 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 "quadmath-imp.h"
22
23
24__complex128
25catanq (__complex128 x)
26{
27 __complex128 res;
28 int rcls = fpclassifyq (__real__ x);
29 int icls = fpclassifyq (__imag__ x);
30
31 if (rcls <= QUADFP_INFINITE || icls <= QUADFP_INFINITE)
32 {
33 if (rcls == QUADFP_INFINITE)
34 {
35 __real__ res = copysignq (M_PI_2q, __real__ x);
36 __imag__ res = copysignq (0.0, __imag__ x);
37 }
38 else if (icls == QUADFP_INFINITE)
39 {
40 if (rcls >= QUADFP_ZERO)
41 __real__ res = copysignq (M_PI_2q, __real__ x);
42 else
43 __real__ res = nanq ("");
44 __imag__ res = copysignq (0.0, __imag__ x);
45 }
46 else if (icls == QUADFP_ZERO || icls == QUADFP_INFINITE)
47 {
48 __real__ res = nanq ("");
49 __imag__ res = copysignq (0.0, __imag__ x);
50 }
51 else
52 {
53 __real__ res = nanq ("");
54 __imag__ res = nanq ("");
55 }
56 }
57 else if (rcls == QUADFP_ZERO && icls == QUADFP_ZERO)
58 {
59 res = x;
60 }
61 else
62 {
63 __float128 r2, num, den;
64
65 r2 = __real__ x * __real__ x;
66
67 den = 1 - r2 - __imag__ x * __imag__ x;
68
69 __real__ res = 0.5 * atan2q (2.0 * __real__ x, den);
70
71 num = __imag__ x + 1.0;
72 num = r2 + num * num;
73
74 den = __imag__ x - 1.0;
75 den = r2 + den * den;
76
77 __imag__ res = 0.25 * logq (num / den);
78 }
79
80 return res;
81}
82