Mat Object: 2 MPI processes
  type: nest
  Matrix object:
    type=nest, rows=2, cols=2
    MatNest structure:
    (0,0) : type=mpiaij, rows=6, cols=6
    (0,1) : type=mpiaij, rows=6, cols=4
    (1,0) : type=mpiaij, rows=4, cols=6
    (1,1) : type=mpiaij, rows=4, cols=4
