code: public static function DPRODUCT($database, $field, $criteria)
      {
          $field = self::fieldExtract($database, $field);
          if ($field === null) {
              return null;
          }
  
          // Return
          return MathTrig::PRODUCT(
              self::getFilteredColumn($database, $field, $criteria)
          );
      }
docs: DPRODUCT.
  
  Multiplies the values in a column of a list or database that match conditions that you specify.
  
  Excel Function:
  DPRODUCT(database,field,criteria)
  
  @category Database Functions
  
  @param mixed[] $database The range of cells that makes up the list or database.
  A database is a list of related data in which rows of related
  information are records, and columns of data are fields. The
  first row of the list contains labels for each column.
  @param int|string $field Indicates which column is used in the function. Enter the
  column label enclosed between double quotation marks, such as
  "Age" or "Yield," or a number (without quotation marks) that
  represents the position of the column within the list: 1 for
  the first column, 2 for the second column, and so on.
  @param mixed[] $criteria The range of cells that contains the conditions you specify.
  You can use any range for the criteria argument, as long as it
  includes at least one column label and at least one cell below
  the column label in which you specify a condition for the
  column.
  
  @return float