:orphan:
# MatILUFactorSymbolic
Performs symbolic ILU factorization of a matrix obtained with `MatGetFactor()` Uses levels of fill only, not drop tolerance. Use `MatLUFactorNumeric()` to complete the factorization. 
## Synopsis
```
#include "petscmat.h" 
PetscErrorCode MatILUFactorSymbolic(Mat fact, Mat mat, IS row, IS col, const MatFactorInfo *info)
```
Collective


## Input Parameters

- ***fact -*** the factorized matrix obtained with `MatGetFactor()`
- ***mat -*** the matrix
- ***row -*** row permutation
- ***col -*** column permutation
- ***info -*** structure containing


```none
      levels - number of levels of fill.
      expected fill - as ratio of original fill.
      1 or 0 - indicating force fill on diagonal (improves robustness for matrices
                missing diagonal entries)
```





## Notes
See [Matrix Factorization](sec_matfactor) for additional information.

Most users should employ the `KSP` interface for linear solvers
instead of working directly with matrix algebra routines such as this.
See, e.g., `KSPCreate()`.

Uses the definition of level of fill as in Y. Saad, 2003


## Developer Note
The Fortran interface is not autogenerated as the
interface definition cannot be generated correctly [due to `MatFactorInfo`]


## References

- **** -*** Y. Saad, Iterative methods for sparse linear systems Philadelphia: Society for Industrial and Applied Mathematics, 2003



## See Also
 [](ch_matrices), `Mat`, [Matrix Factorization](sec_matfactor), `MatGetFactor()`, `MatLUFactorSymbolic()`, `MatLUFactorNumeric()`, `MatCholeskyFactor()`
`MatGetOrdering()`, `MatFactorInfo`

## Level
developer

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/interface/matrix.c.html#MatILUFactorSymbolic">src/mat/interface/matrix.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/aijfact.c.html#MatILUFactorSymbolic_SeqAIJ">MatILUFactorSymbolic_SeqAIJ in src/mat/impls/aij/seq/aijfact.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/kokkos/aijkok.kokkos.cxx.html#MatILUFactorSymbolic_SeqAIJKokkos">MatILUFactorSymbolic_SeqAIJKokkos in src/mat/impls/aij/seq/kokkos/aijkok.kokkos.cxx</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/seqcusparse/aijcusparse.cu.html#MatILUFactorSymbolic_SeqAIJCUSPARSE">MatILUFactorSymbolic_SeqAIJCUSPARSE in src/mat/impls/aij/seq/seqcusparse/aijcusparse.cu</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/aij/seq/seqhipsparse/aijhipsparse.hip.c.html#MatILUFactorSymbolic_SeqAIJHIPSPARSE">MatILUFactorSymbolic_SeqAIJHIPSPARSE in src/mat/impls/aij/seq/seqhipsparse/aijhipsparse.hip.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/mat/impls/baij/seq/baijfact2.c.html#MatILUFactorSymbolic_SeqBAIJ">MatILUFactorSymbolic_SeqBAIJ in src/mat/impls/baij/seq/baijfact2.c</A><BR>


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