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>
5 .\" %%%LICENSE_START(VERBATIM)
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10 .\" Permission is granted to copy and distribute modified versions of this
11 .\" manual under the conditions for verbatim copying, provided that the
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13 .\" permission notice identical to this one.
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16 .\" manual page may be incorrect or out-of-date.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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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 2002-07-25 by Walter Harms
33 .\" (walter.harms@informatik.uni-oldenburg.de)
35 .TH ACOSH 3 2017-09-15 "" "Linux Programmer's Manual"
37 acosh, acoshf, acoshl \- inverse hyperbolic cosine function
42 .BI "double acosh(double " x );
43 .BI "float acoshf(float " x );
44 .BI "long double acoshl(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 cosine of
75 that is the value whose hyperbolic cosine is
78 On success, these functions return the inverse hyperbolic cosine of
83 is a NaN, a NaN is returned.
87 is +1, +0 is returned.
91 is positive infinity, positive infinity is returned.
96 a domain error occurs,
97 and the functions return a NaN.
101 for information on how to determine whether an error has occurred
102 when calling these functions.
104 The following errors can occur:
106 Domain error: \fIx\fP is less than 1
110 An invalid floating-point exception
114 For an explanation of the terms used in this section, see
120 Interface Attribute Value
125 T} Thread safety MT-Safe
128 C99, POSIX.1-2001, POSIX.1-2008.
130 The variant returning