MatGetMultiProcBlock#

Create multiple ‘parallel submatrices’ from a given Mat. Each submatrix can span multiple procs.

Synopsis#

#include "petscmat.h" 
PetscErrorCode MatGetMultiProcBlock(Mat mat, MPI_Comm subComm, MatReuse scall, Mat *subMat)

Collective

Input Parameters#

Output Parameter#

  • subMat - parallel sub-matrices each spanning a given subcomm

Notes#

The submatrix partition across processors is dictated by subComm a communicator obtained by MPI_comm_split() or via PetscSubcommCreate(). The subComm is not restricted to be grouped with consecutive original ranks.

Due the MPI_Comm_split() usage, the parallel layout of the submatrices map directly to the layout of the original matrix [wrt the local row,col partitioning]. So the original ‘DiagonalMat’ naturally maps into the ‘DiagonalMat’ of the subMat, hence it is used directly from the subMat. However the offDiagMat looses some columns - and this is reconstructed with MatSetValues()

This is used by PCBJACOBI when a single block spans multiple MPI ranks

See Also#

Matrices, Mat, MatCreateRedundantMatrix(), MatCreateSubMatrices(), PCBJACOBI

Level#

advanced

Location#

src/mat/interface/matrix.c

Implementations#

MatGetMultiProcBlock_MPIAIJ in src/mat/impls/aij/mpi/mpb_aij.c
MatGetMultiProcBlock_SeqAIJ in src/mat/impls/aij/seq/aij.c
MatGetMultiProcBlock_MPIBAIJ in src/mat/impls/baij/mpi/mpb_baij.c


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