public function format_float($field)
    {
        $precision = 2;
        $m = (float) $this->current_row[$field];
        $this->current_row[$field] =
            is_null($this->current_row[$field])
                ? '-'
                : number_format($m, $precision);
        $this->setTDParam($field, 'align', 'right');
        $this->setTDParam($field, 'style/white-space', 'nowrap');
    }