:orphan:
# PCDeflationSpaceType
Type of deflation 
## Synopsis
```
typedef enum {
  PC_DEFLATION_SPACE_HAAR,
  PC_DEFLATION_SPACE_DB2,
  PC_DEFLATION_SPACE_DB4,
  PC_DEFLATION_SPACE_DB8,
  PC_DEFLATION_SPACE_DB16,
  PC_DEFLATION_SPACE_BIORTH22,
  PC_DEFLATION_SPACE_MEYER,
  PC_DEFLATION_SPACE_AGGREGATION,
  PC_DEFLATION_SPACE_USER
} PCDeflationSpaceType;
```

## Values

- ***`PC_DEFLATION_SPACE_HAAR`        -*** directly assembled based on Haar (db2) wavelet with overflowed filter cuted-off
- ***`PC_DEFLATION_SPACE_DB2`         -*** `MATCOMPOSITE` of 1-lvl matices based on db2 (2 coefficient Daubechies / Haar wavelet)
- ***`PC_DEFLATION_SPACE_DB4`         -*** same as above, but with db4 (4 coefficient Daubechies)
- ***`PC_DEFLATION_SPACE_DB8`         -*** same as above, but with db8 (8 coefficient Daubechies)
- ***`PC_DEFLATION_SPACE_DB16`        -*** same as above, but with db16 (16 coefficient Daubechies)
- ***`PC_DEFLATION_SPACE_BIORTH22`    -*** same as above, but with biorthogonal 2.2 (6 coefficients)
- ***`PC_DEFLATION_SPACE_MEYER`       -*** same as above, but with Meyer/FIR (62 coefficients)
- ***`PC_DEFLATION_SPACE_AGGREGATION` -*** aggregates local indices (given by operator matrix distribution) into a subdomain
- ***`PC_DEFLATION_SPACE_USER`        -*** indicates space set by user





## Note
Wavelet-based space (except Haar) can be used in multilevel deflation.


## See Also
 [](sec_pc), `PCDeflationSetSpaceToCompute()`, `PCDEFLATION`, `PC`

## Level
intermediate

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


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


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