:orphan:
# PCFieldSplitSchurFactType
determines which off-diagonal parts of the approximate block factorization to use 
## Synopsis
```
typedef enum {
  PC_FIELDSPLIT_SCHUR_FACT_DIAG,
  PC_FIELDSPLIT_SCHUR_FACT_LOWER,
  PC_FIELDSPLIT_SCHUR_FACT_UPPER,
  PC_FIELDSPLIT_SCHUR_FACT_FULL
} PCFieldSplitSchurFactType;
```

## Values

- ***`PC_FIELDSPLIT_SCHUR_FACT_DIAG` -*** the preconditioner is solving `D`
- ***`PC_FIELDSPLIT_SCHUR_FACT_LOWER` -*** the preconditioner is solving `L D`
- ***`PC_FIELDSPLIT_SCHUR_FACT_UPPER` -*** the preconditioner is solving `D U`
- ***`PC_FIELDSPLIT_SCHUR_FACT_FULL` -*** the preconditioner is solving `L(D U)`


where the matrix is factorized as
```none
   (A   B)  = (1       0) (A   0) (1  Ainv*B)  = L D U
   (C   E)    (C*Ainv  1) (0   S) (0       1)
```





## See Also
 [](sec_pc), `PCFIELDSPLIT`, `PCFieldSplitSetSchurFactType()`, `PC`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/include/petscpctypes.h.html#PCFieldSplitSchurFactType">include/petscpctypes.h</A>

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/dm/impls/stag/tutorials/ex4.c.html">src/dm/impls/stag/tutorials/ex4.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/include/petscpctypes.h)


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