PETSc version 3.17.0
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# DMPlexPreallocateOperator

Calculate the matrix nonzero pattern based upon the information in the DM, the PetscDS it contains, and the default PetscSection.

### Synopsis

    #include "petscdmplex.h"
    PetscErrorCode DMPlexPreallocateOperator(DM dm, PetscInt bs, PetscInt dnz[], PetscInt onz[], PetscInt dnzu[], PetscInt onzu[], Mat A, PetscBool fillMatrix)

Collective

### Input Parameters

| dm | - The DMPlex
| bs | - The matrix blocksize
| dnz | - An array to hold the number of nonzeros in the diagonal block
| onz | - An array to hold the number of nonzeros in the off-diagonal block
| dnzu | - An array to hold the number of nonzeros in the upper triangle of the diagonal block
| onzu | - An array to hold the number of nonzeros in the upper triangle of the off-diagonal block
| fillMatrix | - If PETSC_TRUE, fill the matrix with zeros

### Output Parameter

| A | - The preallocated matrix

### See Also

DMCreateMatrix()

### Level

advanced

### Location

src/dm/impls/plex/plexpreallocate.c

### Implementations

DMPlexPreallocateOperator_2 in src/dm/impls/plex/plexpreallocate.c
Index of all DMPLEX routines
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Index of all manual pages