# 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 Parameters

- ***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
`MATMPIAIJ` 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
```none
            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
 `DM`, `DMDA`, `DMCreateMatrix()`, `DMDASetGetMatrix()`, `DMSetMatrixPreallocateOnly()`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/da/fdda.c.html#DMDASetBlockFills">src/dm/impls/da/fdda.c</A>


---
[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/dm/impls/da/fdda.c)


[Index of all DMDA routines](index.md)  
[Table of Contents for all manual pages](/docs/manualpages/index.md)  
[Index of all manual pages](/docs/manualpages/singleindex.md)  
