mpi_scatter_matrix.c

MPI_Datatype row_type;
MPI_Datatype col_type;

// Row definition
MPI_Type_vector(DIM_LEN, DIM_LEN, 0, MPI_INT, &row_type);
MPI_Type_commit(&row_type);

// Column definition
MPI_Type_vector(DIM_LEN, 1, DIM_LEN, MPI_INT, &col_type);
MPI_Type_commit(&col_type);

int *sendcnts;
int *disps;
sendcnts = malloc(sizeof(int) * comm_size);
disps = malloc(sizeof(int) * comm_size);
int i;
for(i=0; i<comm_size; i++){
        sendcnts[i] = DIM_LEN / comm_size;
        disps[i] = i;
}
MPI_Scatterv(mat_1, sendcnts, disps, row_type, mat_1, DIM_LEN, row_type, 0, MPI_COMM_WORLD);