Fatal error: Uncaught Error: Class 'Matrix' not found in C:\Apache24\htdocs\PortalUIS_bkp\excel\Spreadsheet\Excel\Classes\PHPExcel\Shared\JAMA\examples\LagrangeInterpolation2.php:40 Stack trace: #0 C:\Apache24\htdocs\PortalUIS_bkp\excel\Spreadsheet\Excel\Classes\PHPExcel\Shared\JAMA\examples\LagrangeInterpolation2.php(55): LagrangeInterpolation->findPolynomialFactors() #1 {main} thrown in C:\Apache24\htdocs\PortalUIS_bkp\excel\Spreadsheet\Excel\Classes\PHPExcel\Shared\JAMA\examples\LagrangeInterpolation2.php on line 40