:orphan:
# MatPreallocateLocation
An alternative to MatPreallocateSet() that puts the nonzero locations into the matrix if it exists 
## Synopsis
```
#include <petscmat.h>
PetscErrorCode MatPreallocateLocations(Mat A,PetscInt row,PetscInt ncols,PetscInt *cols,PetscInt *dnz,PetscInt *onz)
```
Not Collective


## Input Parameters

- ***A -*** matrix
- ***row -*** row where values exist (must be local to this process)
- ***ncols -*** number of columns
- ***cols -*** columns with nonzeros
- ***dnz -*** the array that will be passed to the matrix preallocation routines
- ***onz -*** the other array passed to the matrix preallocation routines


 (since v3.19)


## Notes
This routine is no longer needed since assembling matrices without explicit preallocation will not be slower than
the use of this routine

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

This is a MACRO not a function because it uses a bunch of variables private to the MatPreallocation.... routines.


## See Also
 [](ch_matrices), `MatPreallocateBegin()`, `MatPreallocateSet()`, `MatPreallocateSymmetricSetBlock()`, `MatPreallocateSetLocal()`,
`MatPreallocateSymmetricSetLocalBlock()`

## Level
deprecated

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/include/petscmat.h.html#MatPreallocateLocation">include/petscmat.h</A>


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