# PCSORGetSymmetric
Gets the form the SOR preconditioner is using;   backward, or forward relaxation.  The local variants perform SOR on each processor.  By default forward relaxation is used. 
## Synopsis
```
#include "petscpc.h" 
PetscErrorCode PCSORGetSymmetric(PC pc, MatSORType *flag)
```
Logically Collective


## Input Parameter

- ***pc -*** the preconditioner context



## Output Parameter

- ***flag -*** one of the following


```none
    SOR_FORWARD_SWEEP
    SOR_BACKWARD_SWEEP
    SOR_SYMMETRIC_SWEEP
    SOR_LOCAL_FORWARD_SWEEP
    SOR_LOCAL_BACKWARD_SWEEP
    SOR_LOCAL_SYMMETRIC_SWEEP
```



## Options Database Keys

- ***-pc_sor_symmetric -*** Activates symmetric version
- ***-pc_sor_backward -*** Activates backward version
- ***-pc_sor_local_forward -*** Activates local forward version
- ***-pc_sor_local_symmetric -*** Activates local symmetric version
- ***-pc_sor_local_backward -*** Activates local backward version



## Note
To use the Eisenstat trick with SSOR, employ the `PCEISENSTAT` preconditioner,
which can be chosen with the option

- ***-pc_type eisenstat -*** Activates Eisenstat trick





## See Also
 `PCSOR`, `PCEisenstatSetOmega()`, `PCSORSetIterations()`, `PCSORSetOmega()`, `PCSORSetSymmetric()`

## Level
intermediate

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/sor/sor.c.html#PCSORGetSymmetric">src/ksp/pc/impls/sor/sor.c</A>

## Implementations

<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/sor/sor.c.html#PCSORGetSymmetric_SOR">PCSORGetSymmetric_SOR in src/ksp/pc/impls/sor/sor.c</A><BR>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/ksp/pc/impls/sor/sor.c)


[Index of all PC routines](index.md)  
[Table of Contents for all manual pages](/docs/manualpages/index.md)  
[Index of all manual pages](/docs/manualpages/singleindex.md)  
