code: private function writeCalcPr(XMLWriter $objWriter, $recalcRequired = true)
      {
          $objWriter->startElement('calcPr');
  
          //    Set the calcid to a higher value than Excel itself will use, otherwise Excel will always recalc
          //  If MS Excel does do a recalc, then users opening a file in MS Excel will be prompted to save on exit
          //     because the file has changed
          $objWriter->writeAttribute('calcId', '999999');
          $objWriter->writeAttribute('calcMode', 'auto');
          //    fullCalcOnLoad isn't needed if we've recalculating for the save
          $objWriter->writeAttribute('calcCompleted', ($recalcRequired) ? 1 : 0);
          $objWriter->writeAttribute('fullCalcOnLoad', ($recalcRequired) ? 0 : 1);
  
          $objWriter->endElement();
      }
docs: Write calcPr.
  
  @param XMLWriter $objWriter XML Writer
  @param bool $recalcRequired Indicate whether formulas should be recalculated before writing