# SNESVINEWTONSSLS
Semi-smooth solver for variational inequalities based on Newton's method 
## Options Database Keys

- ***-snes_type <vinewtonssls,vinewtonrsls> a semi-*** smooth solver, a reduced space active set method
- ***-snes_vi_monitor -*** prints the number of active constraints at each iteration.





## References

- **** -*** T. S. Munson, F. Facchinei, M. C. Ferris, A. Fischer, and C. Kanzow. The semismooth
algorithm for large scale complementarity problems. INFORMS Journal on Computing, 13 (2001).
- **** -*** T. S. Munson, and S. Benson. Flexible Complementarity Solvers for Large Scale
Applications, Optimization Methods and Software, 21 (2006).



## Notes
This family of algorithm is much like an interior point method.

The reduced space active set solvers `SNESVINEWTONRSLS` provide an alternative approach that does not result in extremely ill-conditioned linear systems


## See Also
 `SNESVINEWTONRSLS`, `SNESVISetVariableBounds()`, `SNESVISetComputeVariableBounds()`, `SNESCreate()`, `SNES`, `SNESSetType()`, `SNESVINEWTONRSLS`, `SNESNEWTONTR`, `SNESLineSearchSetType()`, `SNESLineSearchSetPostCheck()`, `SNESLineSearchSetPreCheck()`

## Level
beginner

## Location
<A HREF="PETSC_DOC_OUT_ROOT_PLACEHOLDER/src/snes/impls/vi/ss/viss.c.html#SNESVINEWTONSSLS">src/snes/impls/vi/ss/viss.c</A>


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[Edit on GitLab](https://gitlab.com/petsc/petsc/-/edit/release/src/snes/impls/vi/ss/viss.c)


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