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(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
20       _ISOC99_SOURCE; or cc -std=c99
21       acoshf(), acoshl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
22       || _ISOC99_SOURCE; or cc -std=c99
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DESCRIPTION

25       The  acosh()  function  calculates  the inverse hyperbolic cosine of x;
26       that is the value whose hyperbolic cosine is x.
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RETURN VALUE

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

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

51       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
52       4.3BSD, C89.
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SEE ALSO

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

58       This page is part of release 3.25 of the Linux  man-pages  project.   A
59       description  of  the project, and information about reporting bugs, can
60       be found at http://www.kernel.org/doc/man-pages/.
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64                                  2008-08-05                          ACOSH(3)