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# MatILUFactor

Performs in-place ILU factorization of matrix.

## Synopsis

    #include "petscmat.h"
    PetscErrorCode MatILUFactor(Mat mat, IS row, IS col, const MatFactorInfo *info)

Collective

## Input Parameters

- mat - the matrix

- row - row permutation

- col - column permutation

- info - structure containing

          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

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()`.

Probably really in-place only when level of fill is zero, otherwise allocates new space to store factored matrix and deletes previous memory. The preferred approach is to use `MatGetFactor()`, `MatILUFactorSymbolic()`, and `MatILUFactorNumeric()` when not using `KSP`.

## Fortran Note

A valid (non-null) `info` argument must be provided

## See Also

Matrices, `Mat`, Matrix Factorization, `MatILUFactorSymbolic()`, `MatLUFactorNumeric()`, `MatCholeskyFactor()`, `MatFactorInfo`

## Level

developer

## Location

src/mat/interface/matrix.c

## Implementations

MatILUFactor_SeqAIJ() in src/mat/impls/aij/seq/aij.c
MatILUFactor_SeqBAIJ() in src/mat/impls/baij/seq/baij.c

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Index of all manual pages