2 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
3 .\" and Copyright 2008, Linux Foundation, written by Michael Kerrisk
4 .\" <mtk.manpages@gmail.com>
6 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
8 .\" References consulted:
9 .\" Linux libc source code
10 .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
12 .\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
13 .\" Modified 2002-07-25 by Walter Harms
14 .\" (walter.harms@informatik.uni-oldenburg.de)
16 .TH acosh 3 (date) "Linux man-pages (unreleased)"
18 acosh, acoshf, acoshl \- inverse hyperbolic cosine function
21 .RI ( libm ", " \-lm )
26 .BI "double acosh(double " x );
27 .BI "float acoshf(float " x );
28 .BI "long double acoshl(long double " x );
32 Feature Test Macro Requirements for glibc (see
33 .BR feature_test_macros (7)):
38 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
39 || _XOPEN_SOURCE >= 500
40 .\" || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
41 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
42 || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
48 _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
49 || /* Since glibc 2.19: */ _DEFAULT_SOURCE
50 || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
53 These functions calculate the inverse hyperbolic cosine of
55 that is the value whose hyperbolic cosine is
58 On success, these functions return the inverse hyperbolic cosine of
63 is a NaN, a NaN is returned.
67 is +1, +0 is returned.
71 is positive infinity, positive infinity is returned.
76 a domain error occurs,
77 and the functions return a NaN.
81 for information on how to determine whether an error has occurred
82 when calling these functions.
84 The following errors can occur:
86 Domain error: \fIx\fP is less than 1
90 An invalid floating-point exception
94 For an explanation of the terms used in this section, see
100 Interface Attribute Value
107 T} Thread safety MT-Safe
114 The variant returning