public function get_calculator($parameters)
 {
     $p = array('exclude' => $parameters, 'request' => $this->get_request(), 'submit' => wfMessage('fm-calculate')->text(), 'introduction' => wfMessage('fm-intro-mortgage')->text());
     $c = parent::get_calculator($p);
     $c['values']['instalment'] = NULL;
     return $c;
 }
 public function get_calculator($parameters)
 {
     $p = array('exclude' => $parameters, 'request' => $this->get_request(), 'submit' => wfMessage('fm-calculate'), 'introduction' => wfMessage('fm-intro-interest'));
     return parent::get_calculator($p);
 }