What is the difference between MATSEQMAIJ and MATSEQAIJ in PETSc?
Also, where can I find more information on each of the MatTypes? I went to the MatType documentation, but it didn't have anything but the definitions.
MATMAIJ is a matrix type that is mostly used to represent interpolation/restriction operators in multigrid methods. It represents the Kronecker product of a sparse matrix with a small block identity, so that all fields associated with a given discretization node are interpolated in the same way, without needing any redundant storage.