mat0 -- Simple matrix. 4 real 1 1 2.0 1 2 -1.0 2 1 -1.0 2 2 3.0 2 3 -1.0 3 2 -1.0 3 3 3.0 3 4 -1.0 4 3 -1.0 4 4 3.0 0 0 0.0 34.0 0.0 0.0 0.0