2.11BSD#431 - /usr/man/cat3/atanh.0

ASINH(3M)	    UNIX Programmer's Manual		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 absolute value bigger than or equal to 1.

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

AUTHOR
     W. Kahan, Kwok-Choi Ng


Printed 11/26/99	  May 12, 1986				1