ATANH(3)

NAME
1.9 `atanh', `atanhf'--inverse hyperbolic tangent

SYNOPSIS
     #include <math.h>
     double atanh(double X);
     float atanhf(float X);

DESCRIPTION
`atanh' calculates the inverse hyperbolic tangent of X.
   `atanhf' is identical, other than taking and returning `float' values.

RETURNS
`atanh' and `atanhf' return the calculated value.
   If
     X|
   is greater than 1, the global `errno' is set to `EDOM' and the result is a NaN. A `DOMAIN error' is reported.
   If
     X|
   is 1, the global `errno' is set to `EDOM'; and the result is infinity with the same sign as `x'. A `SING error' is reported.
   You can modify the error handling for these routines using `matherr'.

PORTABILITY
Neither `atanh' nor `atanhf' are ANSI C.

SEE ALSO
atanh is part of the library. The full documentation for is maintained as a Texinfo manual. If info and are properly installed at your site, the command

    info

will give you access to the complete manual.