Fatal error: Uncaught Error: Class 'Matrix' not found in /home/drycleanusa2/public_html/library/PHPExcel_1.7.8/PHPExcel/Shared/JAMA/examples/LagrangeInterpolation.php:39 Stack trace: #0 /home/drycleanusa2/public_html/library/PHPExcel_1.7.8/PHPExcel/Shared/JAMA/examples/LagrangeInterpolation.php(54): LagrangeInterpolation->findPolynomialFactors(Array, Array) #1 {main} thrown in /home/drycleanusa2/public_html/library/PHPExcel_1.7.8/PHPExcel/Shared/JAMA/examples/LagrangeInterpolation.php on line 39