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           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
21           _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED || _ISOC99_SOURCE ||
22           _POSIX_C_SOURCE >= 200112L;
23           or cc -std=c99
24       acoshf(), acoshl():
25           _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600 ||
26           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L;
27           or cc -std=c99
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DESCRIPTION

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

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

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

56       C99, POSIX.1-2001.  The variant returning double also conforms to SVr4,
57       4.3BSD, C89.
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SEE ALSO

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

63       This  page  is  part of release 3.53 of the Linux man-pages project.  A
64       description of the project, and information about reporting  bugs,  can
65       be found at http://www.kernel.org/doc/man-pages/.
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69                                  2010-09-20                          ACOSH(3)
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