1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
2 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
3 .\" <mtk.manpages@gmail.com>
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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16 .\" manual page may be incorrect or out-of-date.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
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20 .\" which is licensed free of charge, as they might when working
23 .\" Formatted or processed versions of this manual, if unaccompanied by
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27 .\" References consulted:
28 .\" Linux libc source code
29 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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)
35 .TH ATANH 3 2017-09-15 "" "Linux Programmer's Manual"
37 atanh, atanhf, atanhl \- inverse hyperbolic tangent function
42 .BI "double atanh(double " x );
43 .BI "float atanhf(float " x );
44 .BI "long double atanhl(long double " x );
50 Feature Test Macro Requirements for glibc (see
51 .BR feature_test_macros (7)):
57 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
58 || _XOPEN_SOURCE\ >=\ 500
59 .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
60 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
61 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
67 _ISOC99_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L
68 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
69 || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
73 These functions calculate the inverse hyperbolic tangent of
75 that is the value whose hyperbolic tangent is
78 On success, these functions return the inverse hyperbolic tangent of
83 is a NaN, a NaN is returned.
87 is +0 (\-0), +0 (\-0) is returned.
93 and the functions return
98 respectively, with the mathematically correct sign.
100 If the absolute value of
103 a domain error occurs,
104 and a NaN is returned.
106 .\" POSIX.1-2001 documents an optional range error for subnormal x;
107 .\" glibc 2.8 does not do this.
111 for information on how to determine whether an error has occurred
112 when calling these functions.
114 The following errors can occur:
116 Domain error: \fIx\fP less than \-1 or greater than +1
120 An invalid floating-point exception
124 Pole error: \fIx\fP is +1 or \-1
129 A divide-by-zero floating-point exception
133 For an explanation of the terms used in this section, see
139 Interface Attribute Value
144 T} Thread safety MT-Safe
147 C99, POSIX.1-2001, POSIX.1-2008.
149 The variant returning
154 In glibc 2.9 and earlier,
155 .\" Bug: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6759
156 .\" This can be seen in sysdeps/ieee754/k_standard.c
157 when a pole error occurs,
161 instead of the POSIX-mandated
163 Since version 2.10, glibc does the right thing.