petsc-3.14.5 2021-03-03
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# DMDASetBlockFills

Sets the fill pattern in each block for a multi-component problem of the matrix returned by DMCreateMatrix().

### Synopsis

    #include "petscdmda.h"
    PetscErrorCode  DMDASetBlockFills(DM da,const PetscInt *dfill,const PetscInt *ofill)

Logically Collective on da

### Input Parameter

| da | - the distributed array
| dfill | - the fill pattern in the diagonal block (may be NULL, means use dense block)
| ofill | - the fill pattern in the off-diagonal blocks

### Notes

This only makes sense when you are doing multicomponent problems but using the MPIAIJ matrix format

The format for dfill and ofill is a 2 dimensional dof by dof matrix with 1 entries representing coupling and 0 entries for missing coupling. For example

                dfill[9] = {1, 0, 0,

                            1, 1, 0,

                            0, 1, 1}

means that row 0 is coupled with only itself in the diagonal block, row 1 is coupled with itself and row 0 (in the diagonal block) and row 2 is coupled with itself and row 1 (in the diagonal block).

DMDASetGetMatrix() allows you to provide general code for those more complicated nonzero patterns then can be represented in the dfill, ofill format

Contributed by Glenn Hammond

### See Also

DMCreateMatrix(), DMDASetGetMatrix(), DMSetMatrixPreallocateOnly()

### Level

developer

### Location

src/dm/impls/da/fdda.c
Index of all DMDA routines
Table of Contents for all manual pages
Index of all manual pages