NAME    [Toc]    [Back]

       atanh - inverse hyperbolic tangent function

SYNOPSIS    [Toc]    [Back]

       #include <math.h>

       double atanh(double x);

DESCRIPTION    [Toc]    [Back]

       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    [Toc]    [Back]

       EDOM   x is out of range.

CONFORMING TO    [Toc]    [Back]

       SVID 3, POSIX, BSD 4.3, ISO 9899

SEE ALSO    [Toc]    [Back]

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



				  1993-06-13			      ATANH(3)