generating XLSX file

require_once 'a/Classes/PHPExcel/IOFactory.php';
require_once 'a/Classes/PHPExcel.php';

$formula = '=INDEX({"zz","yy","xx"},MATCH(MAX({11,22,34}),{11,23,34}))';

$objPHPExcel = new PHPExcel();

$objPHPExcel->getActiveSheet()->setCellValue('C1', 'Range #2')
->setCellValue('C2', 5)
->setCellValue('C3', 11)
->setCellValue('C4','')
->setCellValue('C5', $formula);


$objPHPExcel->getActiveSheet()->setTitle('Formulas');
$objPHPExcel->setActiveSheetIndex(0);
$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->save(str_replace('.php', '.xlsx', __FILE__));