function computeCost() {
  global $DB_LINK;
  $this->loadIngred();

  if ($this->liquid == $DB_LINK->true)
    $liquid = true;
  $amount = Units::convertTo($this->amount, $this->unitMapping, $this->unit,
    $this->liquid);
  return ($this->amount * $this->cost);
}

function computeCost($db_link) {

$returnValue = computeCost($DB_LINK);