# KSPSYMMLQ
This code implements the SYMMLQ method. 


## Notes
The operator and the preconditioner must be symmetric for this method.

The preconditioner must be POSITIVE-DEFINITE.

Supports only left preconditioning.


## Reference

- **** -*** Paige & Saunders, Solution of sparse indefinite systems of linear equations, SIAM J. Numer. Anal. 12, 1975.



## See Also
 [](chapter_ksp), `KSPCreate()`, `KSPSetType()`, `KSPType`, `KSP`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/ksp/ksp/impls/symmlq/symmlq.c.html#KSPSYMMLQ">src/ksp/ksp/impls/symmlq/symmlq.c</A>


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


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