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fea681da | 1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
138b47a9 MK |
2 | .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk |
3 | .\" <mtk.manpages@gmail.com> | |
fea681da | 4 | .\" |
93015253 | 5 | .\" %%%LICENSE_START(VERBATIM) |
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6 | .\" Permission is granted to make and distribute verbatim copies of this |
7 | .\" manual provided the copyright notice and this permission notice are | |
8 | .\" preserved on all copies. | |
9 | .\" | |
10 | .\" Permission is granted to copy and distribute modified versions of this | |
11 | .\" manual under the conditions for verbatim copying, provided that the | |
12 | .\" entire resulting derived work is distributed under the terms of a | |
13 | .\" permission notice identical to this one. | |
c13182ef | 14 | .\" |
fea681da MK |
15 | .\" Since the Linux kernel and libraries are constantly changing, this |
16 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
17 | .\" responsibility for errors or omissions, or for damages resulting from | |
18 | .\" the use of the information contained herein. The author(s) may not | |
19 | .\" have taken the same level of care in the production of this manual, | |
20 | .\" which is licensed free of charge, as they might when working | |
21 | .\" professionally. | |
c13182ef | 22 | .\" |
fea681da MK |
23 | .\" Formatted or processed versions of this manual, if unaccompanied by |
24 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 25 | .\" %%%LICENSE_END |
fea681da MK |
26 | .\" |
27 | .\" References consulted: | |
28 | .\" Linux libc source code | |
29 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
30 | .\" 386BSD man pages | |
31 | .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu) | |
32 | .\" Modified 2002-07-27 by Walter Harms | |
33 | .\" (walter.harms@informatik.uni-oldenburg.de) | |
34 | .\" | |
4b8c67d9 | 35 | .TH ATANH 3 2017-09-15 "" "Linux Programmer's Manual" |
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36 | .SH NAME |
37 | atanh, atanhf, atanhl \- inverse hyperbolic tangent function | |
38 | .SH SYNOPSIS | |
39 | .nf | |
40 | .B #include <math.h> | |
68e4db0a | 41 | .PP |
fea681da | 42 | .BI "double atanh(double " x ); |
fea681da | 43 | .BI "float atanhf(float " x ); |
fea681da | 44 | .BI "long double atanhl(long double " x ); |
68e4db0a | 45 | .PP |
fea681da | 46 | .fi |
20c58d70 | 47 | Link with \fI\-lm\fP. |
68e4db0a | 48 | .PP |
cc4615cc MK |
49 | .in -4n |
50 | Feature Test Macro Requirements for glibc (see | |
51 | .BR feature_test_macros (7)): | |
52 | .in | |
68e4db0a | 53 | .PP |
cc4615cc | 54 | .ad l |
138b47a9 | 55 | .BR atanh (): |
8aa728d4 | 56 | .RS 4 |
636ed4d5 MK |
57 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
58 | || _XOPEN_SOURCE\ >=\ 500 | |
cf7fa0a1 | 59 | .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED |
e0a68e13 | 60 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE |
636ed4d5 | 61 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
8aa728d4 | 62 | .RE |
dbfe9c70 | 63 | .PP |
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64 | .BR atanhf (), |
65 | .BR atanhl (): | |
8aa728d4 | 66 | .RS 4 |
636ed4d5 | 67 | _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L |
e0a68e13 | 68 | || /* Since glibc 2.19: */ _DEFAULT_SOURCE |
636ed4d5 | 69 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
8aa728d4 | 70 | .RE |
cc4615cc | 71 | .ad b |
fea681da | 72 | .SH DESCRIPTION |
5600f73a | 73 | These functions calculate the inverse hyperbolic tangent of |
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74 | .IR x ; |
75 | that is the value whose hyperbolic tangent is | |
76 | .IR x . | |
47297adb | 77 | .SH RETURN VALUE |
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78 | On success, these functions return the inverse hyperbolic tangent of |
79 | .IR x . | |
847e0d88 | 80 | .PP |
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81 | If |
82 | .I x | |
83 | is a NaN, a NaN is returned. | |
847e0d88 | 84 | .PP |
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85 | If |
86 | .I x | |
87 | is +0 (\-0), +0 (\-0) is returned. | |
847e0d88 | 88 | .PP |
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89 | If |
90 | .I x | |
91 | is +1 or \-1, | |
efe294cb | 92 | a pole error occurs, |
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93 | and the functions return |
94 | .BR HUGE_VAL , | |
95 | .BR HUGE_VALF , | |
96 | or | |
97 | .BR HUGE_VALL , | |
98 | respectively, with the mathematically correct sign. | |
847e0d88 | 99 | .PP |
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100 | If the absolute value of |
101 | .I x | |
102 | is greater than 1, | |
efe294cb | 103 | a domain error occurs, |
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104 | and a NaN is returned. |
105 | .\" | |
106 | .\" POSIX.1-2001 documents an optional range error for subnormal x; | |
107 | .\" glibc 2.8 does not do this. | |
fea681da | 108 | .SH ERRORS |
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109 | See |
110 | .BR math_error (7) | |
111 | for information on how to determine whether an error has occurred | |
112 | when calling these functions. | |
113 | .PP | |
114 | The following errors can occur: | |
fea681da | 115 | .TP |
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116 | Domain error: \fIx\fP less than \-1 or greater than +1 |
117 | .I errno | |
118 | is set to | |
119 | .BR EDOM . | |
120 | An invalid floating-point exception | |
121 | .RB ( FE_INVALID ) | |
122 | is raised. | |
123 | .TP | |
124 | Pole error: \fIx\fP is +1 or \-1 | |
125 | .I errno | |
126 | is set to | |
385cf745 | 127 | .BR ERANGE |
138b47a9 | 128 | (but see BUGS). |
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129 | A divide-by-zero floating-point exception |
130 | .RB ( FE_DIVBYZERO ) | |
131 | is raised. | |
2ea0152c MS |
132 | .SH ATTRIBUTES |
133 | For an explanation of the terms used in this section, see | |
134 | .BR attributes (7). | |
135 | .TS | |
136 | allbox; | |
137 | lbw28 lb lb | |
138 | l l l. | |
139 | Interface Attribute Value | |
140 | T{ | |
141 | .BR atanh (), | |
142 | .BR atanhf (), | |
143 | .BR atanhl () | |
144 | T} Thread safety MT-Safe | |
145 | .TE | |
47297adb | 146 | .SH CONFORMING TO |
9a74e018 | 147 | C99, POSIX.1-2001, POSIX.1-2008. |
847e0d88 | 148 | .PP |
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149 | The variant returning |
150 | .I double | |
151 | also conforms to | |
7cada58c | 152 | SVr4, 4.3BSD. |
138b47a9 | 153 | .SH BUGS |
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154 | In glibc 2.9 and earlier, |
155 | .\" Bug: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6759 | |
138b47a9 | 156 | .\" This can be seen in sysdeps/ieee754/k_standard.c |
1f6982a0 | 157 | when a pole error occurs, |
138b47a9 | 158 | .I errno |
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159 | as set to |
160 | .BR EDOM | |
161 | instead of the POSIX-mandated | |
138b47a9 | 162 | .BR ERANGE . |
1f6982a0 | 163 | Since version 2.10, glibc does the right thing. |
47297adb | 164 | .SH SEE ALSO |
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165 | .BR acosh (3), |
166 | .BR asinh (3), | |
36268806 | 167 | .BR catanh (3), |
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168 | .BR cosh (3), |
169 | .BR sinh (3), | |
170 | .BR tanh (3) |