#include "petscmat.h" PetscErrorCode MatCreateScatter(MPI_Comm comm,VecScatter scatter,Mat *A)Collective
|comm||- MPI communicator|
|scatter||- a VecScatterContext|
|A||- the matrix|
PETSc requires that matrices and vectors being used for certain operations are partitioned accordingly. For example, when creating a scatter matrix, A, that supports parallel matrix-vector products using MatMult(A,x,y) the user should set the number of local matrix rows to be the number of local elements of the corresponding result vector, y. Note that this is information is required for use of the matrix interface routines, even though the scatter matrix may not actually be physically partitioned.
Developer Notes: This directly accesses information inside the VecScatter associated with the matrix-vector product for this matrix. This is not desirable..