Setting matrix(1,1) = 2.1 Displaying matrix(1,1) 2.1 Displaying indices1, indices2, and values_data. Why are there 3? May be a red herring 1,3452816845,3452816845, 1,3452816845,3452816845, 2.1,-6.27744e+066,-6.27744e+066, Setting matrix(0,1) = 1.1 Displaying indices1, indices2, and values_data. Looks OK to me. 1,0,3452816845, 1,1,3452816845, 2.1,1.1,-6.27744e+066, Sorting the matrix, which would be triggered pre-lookup. Displaying indices1, indices2, and values_data. Messed up now after the read. 0,0,3452816845, 1,1,3452816845, 2.2,1.1,-6.27744e+066, Displaying matrix(1,1). This might be doing a sort that breaks the values? 0 Displaying indices1, indices2, and values_data. Messed up now after the read. 0,1,3452816845, 1,1,3452816845, 2.2,0,-6.27744e+066,