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63551311 | 1 | /* Return arc tangent of complex double value. |
77425c63 | 2 | Copyright (C) 1997, 2011 Free Software Foundation, Inc. |
63551311 UD |
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 | |
41bdb6e2 AJ |
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. | |
63551311 UD |
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 | |
41bdb6e2 | 14 | Lesser General Public License for more details. |
63551311 | 15 | |
41bdb6e2 | 16 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
17 | License along with the GNU C Library; if not, see |
18 | <http://www.gnu.org/licenses/>. */ | |
63551311 UD |
19 | |
20 | #include <complex.h> | |
21 | #include <math.h> | |
9277c064 | 22 | #include <math_private.h> |
63551311 UD |
23 | |
24 | ||
25 | __complex__ double | |
26 | __catan (__complex__ double x) | |
27 | { | |
28 | __complex__ double res; | |
29 | int rcls = fpclassify (__real__ x); | |
30 | int icls = fpclassify (__imag__ x); | |
31 | ||
77425c63 | 32 | if (__builtin_expect (rcls <= FP_INFINITE || icls <= FP_INFINITE, 0)) |
63551311 UD |
33 | { |
34 | if (rcls == FP_INFINITE) | |
35 | { | |
36 | __real__ res = __copysign (M_PI_2, __real__ x); | |
37 | __imag__ res = __copysign (0.0, __imag__ x); | |
38 | } | |
39 | else if (icls == FP_INFINITE) | |
40 | { | |
41 | if (rcls >= FP_ZERO) | |
42 | __real__ res = __copysign (M_PI_2, __real__ x); | |
43 | else | |
44 | __real__ res = __nan (""); | |
45 | __imag__ res = __copysign (0.0, __imag__ x); | |
46 | } | |
47 | else if (icls == FP_ZERO || icls == FP_INFINITE) | |
48 | { | |
49 | __real__ res = __nan (""); | |
50 | __imag__ res = __copysign (0.0, __imag__ x); | |
51 | } | |
52 | else | |
53 | { | |
54 | __real__ res = __nan (""); | |
55 | __imag__ res = __nan (""); | |
56 | } | |
57 | } | |
77425c63 | 58 | else if (__builtin_expect (rcls == FP_ZERO && icls == FP_ZERO, 0)) |
63551311 UD |
59 | { |
60 | res = x; | |
61 | } | |
62 | else | |
63 | { | |
64 | double r2, num, den; | |
65 | ||
66 | r2 = __real__ x * __real__ x; | |
67 | ||
68 | den = 1 - r2 - __imag__ x * __imag__ x; | |
69 | ||
bd355af0 | 70 | __real__ res = 0.5 * __ieee754_atan2 (2.0 * __real__ x, den); |
63551311 UD |
71 | |
72 | num = __imag__ x + 1.0; | |
73 | num = r2 + num * num; | |
74 | ||
75 | den = __imag__ x - 1.0; | |
76 | den = r2 + den * den; | |
77 | ||
78 | __imag__ res = 0.25 * __ieee754_log (num / den); | |
79 | } | |
80 | ||
81 | return res; | |
82 | } | |
83 | weak_alias (__catan, catan) | |
84 | #ifdef NO_LONG_DOUBLE | |
85 | strong_alias (__catan, __catanl) | |
86 | weak_alias (__catan, catanl) | |
87 | #endif |