# Preconditioners for FEM

A number of preconditioners are available when using the finite element method (FEM) (for advanced users only).

- Multilevel ILU/diagonal decomposition (512)
- Preconditioner for a hybrid FEM/MoM solution that uses a multilevel sparse incomplete LU-decomposition with threshold and controlled fill-in.
- Multilevel FEM-MLFMM LU/diagonal decomposition (2010)
- Preconditioner for a hybrid FEM/MLFMM solution that uses a multilevel sparse LU decomposition
of the combined and partitioned, FEM/MLFMM system.
When using the parallel Solver, the factorisation type can be specified.

- Multilevel LU/diagonal decomposition (2050)
- Preconditioner for a hybrid FEM/MoM solution that uses a multilevel sparse LU decomposition of
the partitioned system.
When using the parallel Solver, the factorisation type can be specified.

_{3}field at the CG card.