Mat Object: 2 MPI processes
  type: nest
    MatNest, rows=2, cols=2, structure:
    (0,0) : NULL
    (0,1) : type=diagonal, rows=6, cols=6
    (1,0) : type=constantdiagonal, rows=6, cols=6
    (1,1) : NULL
Mat Object: 2 MPI processes
  type: nest
    MatNest, rows=2, cols=2, structure:
    (0,0) : NULL
    (0,1) : type=diagonal, rows=6, cols=6
    (1,0) : type=constantdiagonal, rows=6, cols=6
    (1,1) : NULL