:orphan:
# MatSORType
What type of (S)SOR to perform 
## Synopsis
```
typedef enum {
  SOR_FORWARD_SWEEP         = 1,
  SOR_BACKWARD_SWEEP        = 2,
  SOR_SYMMETRIC_SWEEP       = 3,
  SOR_LOCAL_FORWARD_SWEEP   = 4,
  SOR_LOCAL_BACKWARD_SWEEP  = 8,
  SOR_LOCAL_SYMMETRIC_SWEEP = 12,
  SOR_ZERO_INITIAL_GUESS    = 16,
  SOR_EISENSTAT             = 32,
  SOR_APPLY_UPPER           = 64,
  SOR_APPLY_LOWER           = 128
} MatSORType;
```

## Values

- ***`SOR_FORWARD_SWEEP` -*** do a sweep from the first row of the matrix to the last
- ***`SOR_BACKWARD_SWEEP` -*** do a sweep from the last row to the first
- ***`SOR_SYMMETRIC_SWEEP` -*** do a sweep from the first row to the last and then back to the first
- ***`SOR_LOCAL_FORWARD_SWEEP` -*** each MPI rank does its own forward sweep with no communication
- ***`SOR_LOCAL_BACKWARD_SWEEP` -*** each MPI rank does its own backward sweep with no communication
- ***`SOR_LOCAL_SYMMETRIC_SWEEP` -*** each MPI rank does its own symmetric sweep with no communication
- ***`SOR_ZERO_INITIAL_GUESS` -*** indicates the initial solution is zero so the sweep can avoid unneeded computation
- ***`SOR_EISENSTAT` -*** apply the Eisentat application of SOR, see `PCEISENSTAT`
- ***`SOR_APPLY_UPPER` -*** multiply by the upper triangular portion of the matrix
- ***`SOR_APPLY_LOWER` -*** multiply by the lower triangular portion of the matrix





## Note
These may be bitwise ORd together


## Developer Note
Since `MatSORType` may be bitwise ORd together, so do not change the numerical values below


## See Also
 [](ch_matrices), `MatSOR()`

## Level
beginner

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

## Examples
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/pde_constrained/tutorials/hyperbolic.c.html">src/tao/pde_constrained/tutorials/hyperbolic.c</A><BR>
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/tao/pde_constrained/tutorials/parabolic.c.html">src/tao/pde_constrained/tutorials/parabolic.c</A><BR>


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