1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
/* Compute complex base 10 logarithm.
Copyright (C) 1997-2015 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 Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <complex.h>
#include <math.h>
#include <math_private.h>
#include <float.h>
/* log_10 (2). */
#define M_LOG10_2 0.3010299956639811952137388947244930267682
/* pi * log10 (e). */
#define M_PI_LOG10E 1.364376353841841347485783625431355770210
__complex__ double
__clog10 (__complex__ double x)
{
__complex__ double result;
int rcls = fpclassify (__real__ x);
int icls = fpclassify (__imag__ x);
if (__glibc_unlikely (rcls == FP_ZERO && icls == FP_ZERO))
{
/* Real and imaginary part are 0.0. */
__imag__ result = signbit (__real__ x) ? M_PI_LOG10E : 0.0;
__imag__ result = __copysign (__imag__ result, __imag__ x);
/* Yes, the following line raises an exception. */
__real__ result = -1.0 / fabs (__real__ x);
}
else if (__glibc_likely (rcls != FP_NAN && icls != FP_NAN))
{
/* Neither real nor imaginary part is NaN. */
double absx = fabs (__real__ x), absy = fabs (__imag__ x);
int scale = 0;
if (absx < absy)
{
double t = absx;
absx = absy;
absy = t;
}
if (absx > DBL_MAX / 2.0)
{
scale = -1;
absx = __scalbn (absx, scale);
absy = (absy >= DBL_MIN * 2.0 ? __scalbn (absy, scale) : 0.0);
}
else if (absx < DBL_MIN && absy < DBL_MIN)
{
scale = DBL_MANT_DIG;
absx = __scalbn (absx, scale);
absy = __scalbn (absy, scale);
}
if (absx == 1.0 && scale == 0)
{
__real__ result = __log1p (absy * absy) * (M_LOG10E / 2.0);
math_check_force_underflow_nonneg (__real__ result);
}
else if (absx > 1.0 && absx < 2.0 && absy < 1.0 && scale == 0)
{
double d2m1 = (absx - 1.0) * (absx + 1.0);
if (absy >= DBL_EPSILON)
d2m1 += absy * absy;
__real__ result = __log1p (d2m1) * (M_LOG10E / 2.0);
}
else if (absx < 1.0
&& absx >= 0.5
&& absy < DBL_EPSILON / 2.0
&& scale == 0)
{
double d2m1 = (absx - 1.0) * (absx + 1.0);
__real__ result = __log1p (d2m1) * (M_LOG10E / 2.0);
}
else if (absx < 1.0
&& absx >= 0.5
&& scale == 0
&& absx * absx + absy * absy >= 0.5)
{
double d2m1 = __x2y2m1 (absx, absy);
__real__ result = __log1p (d2m1) * (M_LOG10E / 2.0);
}
else
{
double d = __ieee754_hypot (absx, absy);
__real__ result = __ieee754_log10 (d) - scale * M_LOG10_2;
}
__imag__ result = M_LOG10E * __ieee754_atan2 (__imag__ x, __real__ x);
}
else
{
__imag__ result = __nan ("");
if (rcls == FP_INFINITE || icls == FP_INFINITE)
/* Real or imaginary part is infinite. */
__real__ result = HUGE_VAL;
else
__real__ result = __nan ("");
}
return result;
}
weak_alias (__clog10, clog10)
#ifdef NO_LONG_DOUBLE
strong_alias (__clog10, __clog10l)
weak_alias (__clog10, clog10l)
#endif
|
