/*
 *  call-seq:
 *     Math.atanh(x)    => float
 *  
 *  Computes the inverse hyperbolic tangent of <i>x</i>.
 */

static VALUE
math_atanh(VALUE obj, VALUE x)
{
    double d;

    Need_Float(x);
    errno = 0;
    d = atanh(RFLOAT_VALUE(x));
    domain_check(d, "atanh");
    return DOUBLE2NUM(d);
}