NAME
acosh, acoshf, acoshl - inverse hyperbolic cosine function
SYNOPSIS
#include <math.h>
double acosh(double x);
float acoshf(float x);
long double acoshl(long double x);
Link with -lm.
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
acosh(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 500 ||
_ISOC99_SOURCE; or cc -std=c99
acoshf(), acoshl(): _BSD_SOURCE || _SVID_SOURCE || _XOPEN_SOURCE >= 600
|| _ISOC99_SOURCE; or cc -std=c99
DESCRIPTION
The acosh() function calculates the inverse hyperbolic cosine of x;
that is the value whose hyperbolic cosine is x.
RETURN VALUE
On success, these functions return the inverse hyperbolic cosine of x.
If x is a NaN, a NaN is returned.
If x is +1, +0 is returned.
If x is positive infinity, positive infinity is returned.
If x is less than 1, a domain error occurs, and the functions return a
NaN.
ERRORS
See math_error(7) for information on how to determine whether an error
has occurred when calling these functions.
The following errors can occur:
Domain error: x is less than 1
errno is set to EDOM. An invalid floating-point exception
(FE_INVALID) is raised.
CONFORMING TO
C99, POSIX.1-2001. The variant returning double also conforms to SVr4,
4.3BSD, C89.
SEE ALSO
asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)
COLOPHON
This page is part of release 3.24 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
2008-08-05