public static function dec2roman($num)
    {

        static $ones = array("", "i", "ii", "iii", "iv", "v", "vi", "vii", "viii", "ix");
        static $tens = array("", "x", "xx", "xxx", "xl", "l", "lx", "lxx", "lxxx", "xc");
        static $hund = array("", "c", "cc", "ccc", "cd", "d", "dc", "dcc", "dccc", "cm");
        static $thou = array("", "m", "mm", "mmm");

        if (!is_numeric($num)) {
            throw new Exception("dec2roman() requires a numeric argument.");
        }

        if ($num > 4000 || $num < 0) {
            return "(out of range)";
        }

        $num = strrev((string)$num);

        $ret = "";
        switch (mb_strlen($num)) {
            /** @noinspection PhpMissingBreakStatementInspection */
            case 4:
                $ret .= $thou[$num[3]];
            /** @noinspection PhpMissingBreakStatementInspection */
            case 3:
                $ret .= $hund[$num[2]];
            /** @noinspection PhpMissingBreakStatementInspection */
            case 2:
                $ret .= $tens[$num[1]];
            /** @noinspection PhpMissingBreakStatementInspection */
            case 1:
                $ret .= $ones[$num[0]];
            default:
                break;
        }

        return $ret;
    }