Ruby: missing/acosh.c Source File

Ruby 3.4.4p34 (2025-05-14 revision a38531fd3f617bf734ef7d6c595325f69985ea1d)

acosh.c
1/**********************************************************************
2
3 acosh.c -
4
5 $Author$
6 created at: Fri Apr 12 00:34:17 JST 2002
7
8 public domain rewrite of acosh(3), asinh(3) and atanh(3)
9
10**********************************************************************/
11
12#include <errno.h>
13#include <float.h>
14#include <math.h>
15#include "ruby.h"
16
17/* DBL_MANT_DIG must be less than 4 times of bits of int */
18#ifndef DBL_MANT_DIG
19#define DBL_MANT_DIG 53 /* in this case, at least 12 digit precision */
20#endif
21#define BIG_CRITERIA_BIT (1<<DBL_MANT_DIG/2)
22#if BIG_CRITERIA_BIT > 0
23#define BIG_CRITERIA (1.0*BIG_CRITERIA_BIT)
24#else
25#define BIG_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/2+1-DBL_MANT_DIG/4)))
26#endif
27#define SMALL_CRITERIA_BIT (1<<(DBL_MANT_DIG/3))
28#if SMALL_CRITERIA_BIT > 0
29#define SMALL_CRITERIA (1.0/SMALL_CRITERIA_BIT)
30#else
31#define SMALL_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/3+1-DBL_MANT_DIG/4)))
32#endif
33
34#ifndef HAVE_ACOSH
35double
36acosh(double x)
37{
38 if (x < 1)
39 x = -1; /* NaN */
40 else if (x == 1)
41 return 0;
42 else if (x > BIG_CRITERIA)
43 x += x;
44 else
45 x += sqrt((x + 1) * (x - 1));
46 return log(x);
47}
48#endif
49
50#ifndef HAVE_ASINH
51double
52asinh(double x)
53{
54 int neg = x < 0;
55 double z = fabs(x);
56
57 if (z < SMALL_CRITERIA) return x;
58 if (z < (1.0/(1<<DBL_MANT_DIG/5))) {
59 double x2 = z * z;
60 z *= 1 + x2 * (-1.0/6.0 + x2 * 3.0/40.0);
61 }
62 else if (z > BIG_CRITERIA) {
63 z = log(z + z);
64 }
65 else {
66 z = log(z + sqrt(z * z + 1));
67 }
68 if (neg) z = -z;
69 return z;
70}
71#endif
72
73#ifndef HAVE_ATANH
74double
75atanh(double x)
76{
77 int neg = x < 0;
78 double z = fabs(x);
79
80 if (z < SMALL_CRITERIA) return x;
81 z = log(z > 1 ? -1 : (1 + z) / (1 - z)) / 2;
82 if (neg) z = -z;
83 if (isinf(z))
84#if defined(ERANGE)
85 errno = ERANGE;
86#elif defined(EDOM)
87 errno = EDOM;
88#else
89 ;
90#endif
91 return z;
92}
93#endif
errno
#define errno
Ractor-aware version of errno.
Definition ruby.h:388