Creates a “process” unassembled matrix,
MATIS, assembled on each process but not across processes.
comm - MPI communicator that will share the matrix
bs - block size of the matrix
m - local size of left vector used in matrix vector products
n - local size of right vector used in matrix vector products
M - global size of left vector used in matrix vector products
N - global size of right vector used in matrix vector products
rmap - local to global map for rows
cmap - local to global map for cols
A - the resulting matrix
n are NOT related to the size of the map; they represent the size of the local parts of the distributed vectors
MatMult() operations. The sizes of rmap and cmap define the size of the local matrices.
NULL, then the local row (column) spaces matches the global space.