Preconditioners for MLFMM
A number of preconditioners are available when using the multilevel fast multipole method (MLFMM) (for advanced users only).
Note: It is recommended to use the default settings.
On the Solve/Run tab, in the
Solution settings group, click the 
Solver settings icon. On the Solver setting dialog, click the
Advanced tab.
Figure 1. The Solver settings dialog (Advanced tab).
Solver settings icon. On the Solver setting dialog, click the
Advanced tab.Figure 1. The Solver settings dialog (Advanced tab).
- Block-Jacobi using LU-decomposition (64)
- Preconditioner for an MLFMM solution where the
inverses of the preconditioner are calculated and applied during every iteration
step.Note: Due to performance reasons, this is the recommended preconditioner.
- Incomplete LU decomposition (ILU) (128)
- Preconditioner for an MLFMM solution that uses an incomplete LU-decomposition of the matrix.
- 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 system.
When using the parallel Solver, the factorisation type can be specified.
- Block-Jacobi preconditioner of MLFMM one-level-up (4096)
- Preconditioner for an MLFMM solution that uses LU-decomposition on entries in the boxes, one-level-up from the finest boxes.
- Sparse approximate inverse (SPAI) (8192)
- Preconditioner for an MLFMM solution.
- Sparse LU (8193)
- Preconditioner for an MLFMM solution that uses a
sparse LU decomposition of the MLFMM near field
matrix.
When using the parallel Solver, the factorisation type can be specified.
Note: The number in brackets corresponds to the value of the I3 field at the CG
card.