PETSc version 3.17.4
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# MatPreallocateSetLocalBlock

Indicates the locations (rows and columns) in the matrix where nonzeros will be inserted using a local number of the rows and columns

### Synopsis

    #include <petscmat.h>
    PetscErrorCode MatPreallocateSetLocalBlock(ISLocalToGlobalMappping map,PetscInt nrows, PetscInt *rows,PetscInt ncols, PetscInt *cols,PetscInt *dnz, PetscInt *onz)

Not Collective

### Input Parameters

| map | - the row mapping from local numbering to global numbering
| nrows | - the number of rows indicated
| rows | - the indices of the rows
| cmap | - the column mapping from local to global numbering
| ncols | - the number of columns in the matrix
| cols | - the columns indicated
| dnz | - the array that will be passed to the matrix preallocation routines
| onz | - the other array passed to the matrix preallocation routines

### Notes

See Users-Manual: ch_performance for more details.

Do not malloc or free dnz and onz, that is handled internally by these routines

### See Also

MatPreallocateFinalize(), MatPreallocateSet(), MatPreallocateSymmetricSetBlock()
MatPreallocateInitialize(), MatPreallocateSymmetricSetLocalBlock()

### Level

intermediate

### Location

src/mat/../../include/petscmat.h
Index of all Mat routines
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