acoshl(3) -- Linux man page

 

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);
 

DESCRIPTION

The acosh() function calculates the inverse hyperbolic cosine of x; that is the value whose hyperbolic cosine is x. If x is less than 1.0, acosh() returns not-a-number (NaN) and errno is set.  

ERRORS

EDOM
x is out of range.
 

CONFORMING TO

SVID 3, POSIX, BSD 4.3, ISO 9899. The float and long double variants are C99 requirements.  

SEE ALSO

asinh(3), atanh(3), cosh(3), sinh(3), tanh(3)