NAME

acosh, acoshf, acoshl —

inverse hyperbolic cosine functions

LIBRARY

Math Library (libm, -lm)

SYNOPSIS

#include <math.h>

double
acosh(double x);

float
acoshf(float x);

long double
acoshl(long double x);

DESCRIPTION

The acosh(), acoshf(), and acoshl() functions compute the inverse hyperbolic cosine of the real argument x. For a discussion of error due to roundoff, see math(3).

RETURN VALUES

These functions return the inverse hyperbolic cosine of x. If the argument is less than 1, acosh() raises an invalid exception and returns an NaN.

HISTORY

The acosh(), acoshf(), and acoshl() functions appeared in 4.3BSD, FreeBSD 2.0, and FreeBSD 10.0, respectively.