acosh(3) - f38

1acosh(3)                   Library Functions Manual                   acosh(3)
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NAME

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

9       Math library (libm, -lm)
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SYNOPSIS

12       #include <math.h>
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14       double acosh(double x);
15       float acoshf(float x);
16       long double acoshl(long double x);
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18   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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20       acosh():
21           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
22               || _XOPEN_SOURCE >= 500
23               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
24               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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26       acoshf(), acoshl():
27           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
28               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
29               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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DESCRIPTION

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

36       On success, these functions return the inverse hyperbolic cosine of x.
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38       If x is a NaN, a NaN is returned.
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40       If x is +1, +0 is returned.
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42       If x is positive infinity, positive infinity is returned.
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44       If x is less than 1, a domain error occurs, and the functions return  a
45       NaN.
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ERRORS

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

58       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
59       tributes(7).
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61       ┌────────────────────────────────────────────┬───────────────┬─────────┐
62       │Interface                                   │ Attribute     │ Value   │
63       ├────────────────────────────────────────────┼───────────────┼─────────┤
64       │acosh(), acoshf(), acoshl()                 │ Thread safety │ MT-Safe │
65       └────────────────────────────────────────────┴───────────────┴─────────┘
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STANDARDS

68       C11, POSIX.1-2008.
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HISTORY

71       C99, POSIX.1-2001.
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73       The variant returning double also conforms to SVr4, 4.3BSD.
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