public function toSeconds($d)
    {
        $v = $this->getValue();
        if ($v < self::SECONDS) {
            return $d/($this->c3/$this->{'c'.$v});
        } else {
            return $this->x($d, $this->{'c'.$v}/$this->c3, PHP_INT_MAX/($this->{'c'.$v}/$this->c3));
        }
    }