acosh, acoshf, acoshl - inverse hyperbolic cosine function
#include <math.h> double acosh(double x); float acoshf(float x); long double acoshl(long double x);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 500 || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
_ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L || /* Since glibc 2.19: */ _DEFAULT_SOURCE || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
These functions calculate the inverse hyperbolic cosine of
x; that is the value whose hyperbolic cosine is
On success, these functions return the inverse hyperbolic cosine of
x is a NaN, a NaN is returned.
x is +1, +0 is returned.
x is positive infinity, positive infinity is returned.
x is less than 1, a domain error occurs, and the functions return a NaN.
See math_error(7) for information on how to determine whether an error has occurred when calling these functions.
The following errors can occur:
xis less than 1
errno is set to EDOM. An invalid floating-point exception (FE_INVALID) is raised.
C99, POSIX.1-2001, POSIX.1-2008.
The variant returning
double also conforms to SVr4, 4.3BSD.
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