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192.168.1.100 / T106_DC / d6531900ad4b345585d1874339d1db84fbcde5b8 / . / ap / libc / glibc / glibc-2.23 / math / s_catanf.c
blob: 63e6b6e703ec1753b524beefa43bc4619ae00d08 [file] [log] [blame]
xf.libdd93d52023-05-12 07:10:14 -0700[diff] [blame]1/* Return arc tangent of complex float value.
2 Copyright (C) 1997-2016 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, see
18 <http://www.gnu.org/licenses/>. */
19
20#include <complex.h>
21#include <math.h>
22#include <math_private.h>
23#include <float.h>
24
25__complex__ float
26__catanf (__complex__ float x)
27{
28 __complex__ float res;
29 int rcls = fpclassify (__real__ x);
30 int icls = fpclassify (__imag__ x);
31
32 if (__glibc_unlikely (rcls <= FP_INFINITE || icls <= FP_INFINITE))
33 {
34 if (rcls == FP_INFINITE)
35 {
36 __real__ res = __copysignf (M_PI_2, __real__ x);
37 __imag__ res = __copysignf (0.0, __imag__ x);
38 }
39 else if (icls == FP_INFINITE)
40 {
41 if (rcls >= FP_ZERO)
42 __real__ res = __copysignf (M_PI_2, __real__ x);
43 else
44 __real__ res = __nanf ("");
45 __imag__ res = __copysignf (0.0, __imag__ x);
46 }
47 else if (icls == FP_ZERO || icls == FP_INFINITE)
48 {
49 __real__ res = __nanf ("");
50 __imag__ res = __copysignf (0.0, __imag__ x);
51 }
52 else
53 {
54 __real__ res = __nanf ("");
55 __imag__ res = __nanf ("");
56 }
57 }
58 else if (__glibc_unlikely (rcls == FP_ZERO && icls == FP_ZERO))
59 {
60 res = x;
61 }
62 else
63 {
64 if (fabsf (__real__ x) >= 16.0f / FLT_EPSILON
65 || fabsf (__imag__ x) >= 16.0f / FLT_EPSILON)
66 {
67 __real__ res = __copysignf ((float) M_PI_2, __real__ x);
68 if (fabsf (__real__ x) <= 1.0f)
69 __imag__ res = 1.0f / __imag__ x;
70 else if (fabsf (__imag__ x) <= 1.0f)
71 __imag__ res = __imag__ x / __real__ x / __real__ x;
72 else
73 {
74 float h = __ieee754_hypotf (__real__ x / 2.0f,
75 __imag__ x / 2.0f);
76 __imag__ res = __imag__ x / h / h / 4.0f;
77 }
78 }
79 else
80 {
81 float den, absx, absy;
82
83 absx = fabsf (__real__ x);
84 absy = fabsf (__imag__ x);
85 if (absx < absy)
86 {
87 float t = absx;
88 absx = absy;
89 absy = t;
90 }
91
92 if (absy < FLT_EPSILON / 2.0f)
93 {
94 den = (1.0f - absx) * (1.0f + absx);
95 if (den == -0.0f)
96 den = 0.0f;
97 }
98 else if (absx >= 1.0f)
99 den = (1.0f - absx) * (1.0f + absx) - absy * absy;
100 else if (absx >= 0.75f || absy >= 0.5f)
101 den = -__x2y2m1f (absx, absy);
102 else
103 den = (1.0f - absx) * (1.0f + absx) - absy * absy;
104
105 __real__ res = 0.5f * __ieee754_atan2f (2.0f * __real__ x, den);
106
107 if (fabsf (__imag__ x) == 1.0f
108 && fabsf (__real__ x) < FLT_EPSILON * FLT_EPSILON)
109 __imag__ res = (__copysignf (0.5f, __imag__ x)
110 * ((float) M_LN2
111 - __ieee754_logf (fabsf (__real__ x))));
112 else
113 {
114 float r2 = 0.0f, num, f;
115
116 if (fabsf (__real__ x) >= FLT_EPSILON * FLT_EPSILON)
117 r2 = __real__ x * __real__ x;
118
119 num = __imag__ x + 1.0f;
120 num = r2 + num * num;
121
122 den = __imag__ x - 1.0f;
123 den = r2 + den * den;
124
125 f = num / den;
126 if (f < 0.5f)
127 __imag__ res = 0.25f * __ieee754_logf (f);
128 else
129 {
130 num = 4.0f * __imag__ x;
131 __imag__ res = 0.25f * __log1pf (num / den);
132 }
133 }
134 }
135
136 math_check_force_underflow_complex (res);
137 }
138
139 return res;
140}
141#ifndef __catanf
142weak_alias (__catanf, catanf)
143#endif