NAME

asinh, acosh, atanh − inverse hyperbolic functions

SYNOPSIS

#include <math.h>

double asinh(x)
double x;

double acosh(x)
double x;

double atanh(x)
double x;

DESCRIPTION

These functions compute the designated inverse hyperbolic functions for real arguments. 

ERROR (due to Roundoff etc.)

These functions inherit much of their error from log1p described in exp(3M).  On a VAX, acosh is accurate to about 3 ulps, asinh and atanh to about 2 ulps.  An ulp is one Unit in the Last Place carried. 

DIAGNOSTICS

Acosh returns the reserved operand on a VAX if the argument is less than 1. 

Atanh returns the reserved operand on a VAX if the argument has absolute value bigger than or equal to 1. 

SEE ALSO

math(3M), exp(3M), infnan(3M)

AUTHOR

W. Kahan, Kwok−Choi Ng

4.3 Berkeley Distribution  —  Revision 1.2 of 19/10/88