ATANH(3)                  386BSD Programmer's Manual                  ATANH(3)

NAME
     atanh - inverse hyperbolic tangent function

SYNOPSIS
     #include <math.h>

     double
     atanh(double x)

DESCRIPTION
     The atanh() function computes the inverse hyperbolic tangent of the real
     argument x. For a discussion of error due to roundoff, see math(3).

RETURN VALUES
     The atanh() function returns the inverse hyperbolic tangent of x if
     successful.  On the VAX and Tahoe, if the argument has absolute value
     bigger than or equal to 1, atanh() sets the global variable errno to EDOM
     and a reserved operand fault is generated.

SEE ALSO
     acosh(3),  asinh(3),  exp(3),  infnan(3) math(3),

HISTORY
     The atanh() function appeared in 4.3BSD.

4.3 Berkeley Distribution         May 6, 1991                                1