Fatal error: Uncaught Error: Class 'Matrix' not found in C:\Apache241\htdocs\phpexcel\Classes\PHPExcel\Shared\JAMA\examples\LagrangeInterpolation2.php:40 Stack trace: #0 C:\Apache241\htdocs\phpexcel\Classes\PHPExcel\Shared\JAMA\examples\LagrangeInterpolation2.php(55): LagrangeInterpolation->findPolynomialFactors(Array, Array) #1 {main} thrown in C:\Apache241\htdocs\phpexcel\Classes\PHPExcel\Shared\JAMA\examples\LagrangeInterpolation2.php on line 40