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():
_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
|| _XOPEN_SOURCE >= 500
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE ||
_SVID_SOURCE
acoshf(), acoshl():
_ISOC99_SOURCE ||
_POSIX_C_SOURCE >= 200112L
|| /* Since glibc 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE ||
_SVID_SOURCE
DESCRIPTION
These functions calculate 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.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).
CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning double also conforms to SVr4, 4.3BSD.
SEE ALSO
asinh(3), atanh(3), cacosh(3), cosh(3), sinh(3), tanh(3)
COLOPHON
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