redhat man page for atanh

ATANH(3)						     Linux Programmer's Manual							  ATANH(3)

NAME
       atanh - inverse hyperbolic tangent function

SYNOPSIS
       #include <math.h>

       double atanh(double x);

DESCRIPTION
       The  atanh()  function  calculates  the	inverse hyperbolic tangent of x; that is the value whose hyperbolic tangent is x.  If the absolute
       value of x is greater 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

SEE ALSO
       asinh(3), acosh(3), cosh(3), sinh(3), tanh(3)

								    1993-06-13								  ATANH(3)