1ACOSH(3)                   Linux Programmer's Manual                  ACOSH(3)
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NAME

6       acosh, acoshf, acoshl - inverse hyperbolic cosine function
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SYNOPSIS

9       #include <math.h>
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11       double acosh(double x);
12       float acoshf(float x);
13       long double acoshl(long double x);
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15       Link with -lm.
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       acosh():
20           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
21               || _XOPEN_SOURCE >= 500
22               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
23               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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25       acoshf(), acoshl():
26           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
27               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
28               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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DESCRIPTION

31       These  functions  calculate the inverse hyperbolic cosine of x; that is
32       the value whose hyperbolic cosine is x.
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RETURN VALUE

35       On success, these functions return the inverse hyperbolic cosine of x.
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37       If x is a NaN, a NaN is returned.
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39       If x is +1, +0 is returned.
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41       If x is positive infinity, positive infinity is returned.
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43       If x is less than 1, a domain error occurs, and the functions return  a
44       NaN.
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ERRORS

47       See  math_error(7) for information on how to determine whether an error
48       has occurred when calling these functions.
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50       The following errors can occur:
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52       Domain error: x is less than 1
53              errno is set  to  EDOM.   An  invalid  floating-point  exception
54              (FE_INVALID) is raised.
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ATTRIBUTES

57       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
58       tributes(7).
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60       ┌────────────────────────────────────────────┬───────────────┬─────────┐
61       │Interface                                   │ Attribute     │ Value   │
62       ├────────────────────────────────────────────┼───────────────┼─────────┤
63       │acosh(), acoshf(), acoshl()                 │ Thread safety │ MT-Safe │
64       └────────────────────────────────────────────┴───────────────┴─────────┘
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CONFORMING TO

67       C99, POSIX.1-2001, POSIX.1-2008.
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69       The variant returning double also conforms to SVr4, 4.3BSD.
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SEE ALSO

72       asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)
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COLOPHON

75       This page is part of release 5.12 of the Linux  man-pages  project.   A
76       description  of  the project, information about reporting bugs, and the
77       latest    version    of    this    page,    can     be     found     at
78       https://www.kernel.org/doc/man-pages/.
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82                                  2021-03-22                          ACOSH(3)
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