blob: 6a9daffa5fc79564e112cab04e0760fed3d6cba4 (
plain)
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
|
/**********************************************************************
acosh.c -
$Author$
$Date$
created at: Fri Apr 12 00:34:17 JST 2002
public domain rewrite of acosh(3), asinh(3) and atanh(3)
**********************************************************************/
#include <errno.h>
#include <float.h>
#include <math.h>
/* DBL_MANT_DIG must be less than 4 times of bits of int */
#ifdef DBL_MANT_DIG
#define DBL_MANT_DIG 53 /* in this case, at least 12 digit precision */
#endif
#define BIG_CRITERIA_BIT (1<<DBL_MANT_DIG/2)
#if BIG_CRITERIA_BIT > 0
#define BIG_CRITERIA (1.0*BIG_CRITERIA_BIT)
#else
#define BIG_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/2+1-DBL_MANT_DIG/4)))
#endif
#define SMALL_CRITERIA_BIT (1<<(DBL_MANT_DIG/3))
#if SMALL_CRITERIA_BIT > 0
#define SMALL_CRITERIA (1.0/SMALL_CRITERIA_BIT)
#else
#define SMALL_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/3+1-DBL_MANT_DIG/4)))
#endif
#ifndef HAVE_ACOSH
double
acosh(x)
double x;
{
if (x < 1)
x = -1; /* NaN */
else if (x == 1)
return 0;
else if (x > BIG_CRITERIA)
x += x;
else
x += sqrt((x + 1) * (x - 1));
return log(x);
}
#endif
#ifndef HAVE_ASINH
double
asinh(x)
double x;
{
int neg = x < 0;
double z = fabs(x);
if (z < SMALL_CRITERIA) return x;
if (z < (1.0/(1<<DBL_MANT_DIG/5))) {
double x2 = z * z;
z *= 1 + x2 * (-1.0/6.0 + x2 * 3.0/40.0);
}
else if (z > BIG_CRITERIA) {
z = log(z + z);
}
else {
z = log(z + sqrt(z * z + 1));
}
if (neg) z = -z;
return z;
}
#endif
#ifndef HAVE_ATANH
double
atanh(x)
double x;
{
int neg = x < 0;
double z = fabs(x);
if (z < SMALL_CRITERIA) return x;
z = log(z > 1 ? -1 : (1 + z) / (1 - z)) / 2;
if (neg) z = -z;
return z;
}
#endif
|
