Верхофф (почти Медофф =D)

class Verhoff {

    private $_d = array(
        //k=  0  1  2  3  4  5  6  7  8  9
        array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), //j=0
        array(1, 2, 3, 4, 0, 6, 7, 8, 9, 5), //j=1
        array(2, 3, 4, 0, 1, 7, 8, 9, 5, 6), //j=2
        array(3, 4, 0, 1, 2, 8, 9, 5, 6, 7), //j=3
        array(4, 0, 1, 2, 3, 9, 5, 6, 7, 8), //j=4
        array(5, 9, 8, 7, 6, 0, 4, 3, 2, 1), //j=5
        array(6, 5, 9, 8, 7, 1, 0, 4, 3, 2), //j=6
        array(7, 6, 5, 9, 8, 2, 1, 0, 4, 3), //j=7
        array(8, 7, 6, 5, 9, 3, 2, 1, 0, 4), //j=8
        array(9, 8, 7, 6, 5, 4, 3, 2, 1, 0)  //j=9
    ); //d(j, k)
    private $_p = array(
        //y=  0  1  2  3  4  5  6  7  8  9
        array(0, 1, 2, 3, 4, 5, 6, 7, 8, 9), //x=0
        array(1, 5, 7, 6, 2, 8, 3, 0, 9, 4), //x=1
        array(5, 8, 0, 3, 7, 9, 6, 1, 4, 2), //x=2
        array(8, 9, 1, 6, 0, 4, 3, 5, 2, 7), //x=3
        array(9, 4, 5, 3, 1, 2, 6, 8, 7, 0), //x=4
        array(4, 2, 8, 6, 5, 7, 3, 9, 0, 1), //x=5
        array(2, 7, 9, 3, 8, 0, 6, 4, 1, 5), //x=6
        array(7, 0, 4, 6, 9, 1, 3, 2, 5, 8)  //x=7
    ); //p(x, y)
    //
    //j =                 0  1  2  3  4  5  6  7  8  9
    private $_inv = array(0, 4, 3, 2, 1, 5, 6, 7, 8, 9);
    private $_num;

    public function __construct() {

    }

    private function _inv($i) {
        return $this->_inv[$i];
    }

    public function create($num) {
        $c = 0;
        $num = str_replace('_', ord('_'), $num);
        $this->_num = $num;
        $num = strrev($num);
        for ($i = 0; $i < strlen($num); $i++) {
            $c = $this->_d[$c][$this->_p[(($i + 1) % 8)][$num[$i]]];
        }
        return $this->_inv($c);
    }

    public function makesum() {
        $sumdig = $this->create($this->_num);
        return $this->_num . $sumdig;
    }

    public function test($num) {
        $control = substr($num, -1);
        $testnum = substr($num, 0, strlen($num) - 1);
        if ($this->create($testnum) == $control) {
            return true;
        }
        else
            return FALSE;
    }

}