function computedata(&$crossm, &$crossd, &$letters, $maxwords)
 {
     if (!cross::computedata($crossm, $crossd, $maxwords)) {
         return false;
     }
     $letters = $this->computeletters($crossm, $crossd);
     return true;
 }
 public function computedata(&$crossm, &$crossd, &$letters, $minwords, $maxwords, $mtimelimit = 3)
 {
     if (!cross::computedata($crossm, $crossd, $letters, $minwords, $maxwords, $mtimelimit)) {
         return false;
     }
     $letters = $this->computeletters($crossm, $crossd);
     return true;
 }