LU decomposition: 16 random 2x2 matrices

Fatal error: Uncaught Error: Class 'Matrix' not found in /opt/lampp/htdocs/dhtmlxSuite_v5.1/codebase/grid-excel-php/lib/PHPExcel/Shared/JAMA/examples/benchmark.php:67 Stack trace: #0 /opt/lampp/htdocs/dhtmlxSuite_v5.1/codebase/grid-excel-php/lib/PHPExcel/Shared/JAMA/examples/benchmark.php(204): Benchmark->runLU(2, 16) #1 {main} thrown in /opt/lampp/htdocs/dhtmlxSuite_v5.1/codebase/grid-excel-php/lib/PHPExcel/Shared/JAMA/examples/benchmark.php on line 67