public static function artanh($z) {
        if (!($z instanceof Complex)) $z = static::parse($z);

        return static::div(static::log(static::div(static::add(1,$z), static::sub(1,$z))),2);
    }
public static function artanh($z) {
        if (!($z instanceof Complex)) $z = static::parse($z);

        return static::div(static::log(static::div(static::add(1,$z), static::sub(1,$z))),2);
    }
public static function artanh ( $ z ) { if ( ! ( $ z instanceof Complex ) ) $ z = static :: parse ( $ z ) ; return static :: div ( static :: log ( static :: div ( static :: add ( 1 , $ z ) , static :: sub ( 1 , $ z ) ) ) , 2 ) ; }
complex inverse hyperbolic tangent function

Complex::artanh($z) computes and returns the principal branch of artanh($z)


@param mixed $z (Complex, or parsable to Complex)
@retval Complex
complex inverse hyperbolic tangent function