7.12.5.1 The acosh functions
Synopsis
#include <math.h>
double acosh(double x);
float acoshf(float x);
long double acoshl(long double x);
Description
The acosh functions compute the (nonnegative) arc hyperbolic cosine of x. A domain error occurs for arguments less than 1.
Returns
The acosh functions return arcosh x in the interval [0, +(inf)].