protected function rationalCompare(RationalType $a, RationalType $b)
    {
        $res = $this->calculator->rationalSub($a, $b);

        if ($res->numerator()->get() == 0) {
            return 0;
        }
        if ($res->numerator()->get() < 0) {
            return -1;
        }
        return 1;
    }