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# PCSPAI
Use the Sparse Approximate Inverse method 
## Options Database Keys

- ***-pc_spai_epsilon <eps> -*** set tolerance
- ***-pc_spai_nbstep <n> -*** set nbsteps
- ***-pc_spai_max <m> -*** set max
- ***-pc_spai_max_new <m> -*** set maxnew
- ***-pc_spai_block_size <n> -*** set block size
- ***-pc_spai_cache_size <n> -*** set cache size
- ***-pc_spai_sp <m> -*** set sp
- ***-pc_spai_set_verbose <true,false> -*** verbose output





## Note
This only works with `MATAIJ` matrices.


## References
. * -  Grote and Barnard (SIAM J. Sci. Comput.; vol 18, nr 3)


## See Also
 `PCCreate()`, `PCSetType()`, `PCType`, `PC`,
`PCSPAISetEpsilon()`, `PCSPAISetMax()`, `PCSPAISetMaxNew()`, `PCSPAISetBlockSize()`,
`PCSPAISetVerbose()`, `PCSPAISetSp()`, `PCSPAISetNBSteps()`, `PCSPAISetCacheSize()`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/pc/impls/spai/ispai.c.html#PCSPAI">src/ksp/pc/impls/spai/ispai.c</A>


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


[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)