1 | |
---|
2 | /* @(#)w_acosh.c 5.1 93/09/24 */ |
---|
3 | /* |
---|
4 | * ==================================================== |
---|
5 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
---|
6 | * |
---|
7 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
---|
8 | * Permission to use, copy, modify, and distribute this |
---|
9 | * software is freely granted, provided that this notice |
---|
10 | * is preserved. |
---|
11 | * ==================================================== |
---|
12 | * |
---|
13 | */ |
---|
14 | |
---|
15 | /* |
---|
16 | FUNCTION |
---|
17 | <<acosh>>, <<acoshf>>---inverse hyperbolic cosine |
---|
18 | |
---|
19 | INDEX |
---|
20 | acosh |
---|
21 | INDEX |
---|
22 | acoshf |
---|
23 | |
---|
24 | SYNOPSIS |
---|
25 | #include <math.h> |
---|
26 | double acosh(double <[x]>); |
---|
27 | float acoshf(float <[x]>); |
---|
28 | |
---|
29 | DESCRIPTION |
---|
30 | <<acosh>> calculates the inverse hyperbolic cosine of <[x]>. |
---|
31 | <<acosh>> is defined as |
---|
32 | @ifnottex |
---|
33 | . log(<[x]> + sqrt(<[x]>*<[x]>-1)) |
---|
34 | @end ifnottex |
---|
35 | @tex |
---|
36 | $$ln\Bigl(x + \sqrt{x^2-1}\Bigr)$$ |
---|
37 | @end tex |
---|
38 | |
---|
39 | <[x]> must be a number greater than or equal to 1. |
---|
40 | |
---|
41 | <<acoshf>> is identical, other than taking and returning floats. |
---|
42 | |
---|
43 | RETURNS |
---|
44 | <<acosh>> and <<acoshf>> return the calculated value. If <[x]> |
---|
45 | less than 1, the return value is NaN and <<errno>> is set to <<EDOM>>. |
---|
46 | |
---|
47 | You can change the error-handling behavior with the non-ANSI |
---|
48 | <<matherr>> function. |
---|
49 | |
---|
50 | PORTABILITY |
---|
51 | Neither <<acosh>> nor <<acoshf>> are ANSI C. They are not recommended |
---|
52 | for portable programs. |
---|
53 | |
---|
54 | |
---|
55 | QUICKREF |
---|
56 | ansi svid posix rentrant |
---|
57 | acos n,n,n,m |
---|
58 | acosf n,n,n,m |
---|
59 | |
---|
60 | MATHREF |
---|
61 | acosh, NAN, arg,DOMAIN,EDOM |
---|
62 | acosh, < 1.0, NAN,DOMAIN,EDOM |
---|
63 | acosh, >=1.0, acosh(arg),,, |
---|
64 | |
---|
65 | MATHREF |
---|
66 | acoshf, NAN, arg,DOMAIN,EDOM |
---|
67 | acoshf, < 1.0, NAN,DOMAIN,EDOM |
---|
68 | acoshf, >=1.0, acosh(arg),,, |
---|
69 | |
---|
70 | */ |
---|
71 | |
---|
72 | /* |
---|
73 | * wrapper acosh(x) |
---|
74 | */ |
---|
75 | |
---|
76 | #include "fdlibm.h" |
---|
77 | #include <errno.h> |
---|
78 | |
---|
79 | #ifndef _DOUBLE_IS_32BITS |
---|
80 | |
---|
81 | #ifdef __STDC__ |
---|
82 | double acosh(double x) /* wrapper acosh */ |
---|
83 | #else |
---|
84 | double acosh(x) /* wrapper acosh */ |
---|
85 | double x; |
---|
86 | #endif |
---|
87 | { |
---|
88 | #ifdef _IEEE_LIBM |
---|
89 | return __ieee754_acosh(x); |
---|
90 | #else |
---|
91 | double z; |
---|
92 | struct exception exc; |
---|
93 | z = __ieee754_acosh(x); |
---|
94 | if(_LIB_VERSION == _IEEE_ || isnan(x)) return z; |
---|
95 | if(x<1.0) { |
---|
96 | /* acosh(x<1) */ |
---|
97 | exc.type = DOMAIN; |
---|
98 | exc.name = "acosh"; |
---|
99 | exc.err = 0; |
---|
100 | exc.arg1 = exc.arg2 = x; |
---|
101 | exc.retval = 0.0/0.0; |
---|
102 | if (_LIB_VERSION == _POSIX_) |
---|
103 | errno = EDOM; |
---|
104 | else if (!matherr(&exc)) { |
---|
105 | errno = EDOM; |
---|
106 | } |
---|
107 | if (exc.err != 0) |
---|
108 | errno = exc.err; |
---|
109 | return exc.retval; |
---|
110 | } else |
---|
111 | return z; |
---|
112 | #endif |
---|
113 | } |
---|
114 | |
---|
115 | #endif /* defined(_DOUBLE_IS_32BITS) */ |
---|