4.3BSD - /usr/man/cat3/atanh.0

ASINH(3M)                                                            ASINH(3M)


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 abso‐
       lute 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        May 12, 1986                        ASINH(3M)