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
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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 2010-09-11 "" "Linux Programmer's Manual"
37 atanh, atanhf, atanhl \- inverse hyperbolic tangent function
42 .BI "double atanh(double " x );
44 .BI "float atanhf(float " x );
46 .BI "long double atanhl(long double " x );
52 Feature Test Macro Requirements for glibc (see
53 .BR feature_test_macros (7)):
59 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
60 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
61 _POSIX_C_SOURCE\ >=\ 200112L;
70 _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 600 || _ISOC99_SOURCE ||
71 _POSIX_C_SOURCE\ >=\ 200112L;
80 function calculates the inverse hyperbolic tangent of
82 that is the value whose hyperbolic tangent is
85 On success, these functions return the inverse hyperbolic tangent of
90 is a NaN, a NaN is returned.
94 is +0 (\-0), +0 (\-0) is returned.
100 and the functions return
105 respectively, with the mathematically correct sign.
107 If the absolute value of
110 a domain error occurs,
111 and a NaN is returned.
113 .\" POSIX.1-2001 documents an optional range error for subnormal x;
114 .\" glibc 2.8 does not do this.
118 for information on how to determine whether an error has occurred
119 when calling these functions.
121 The following errors can occur:
123 Domain error: \fIx\fP less than \-1 or greater than +1
127 An invalid floating-point exception
131 Pole error: \fIx\fP is +1 or \-1
136 A divide-by-zero floating-point exception
141 The variant returning
146 In glibc 2.9 and earlier,
147 .\" Bug: http://sources.redhat.com/bugzilla/show_bug.cgi?id=6759
148 .\" This can be seen in sysdeps/ieee754/k_standard.c
149 when a pole error occurs,
153 instead of the POSIX-mandated
155 Since version 2.10, glibc does the right thing.