Hello Florian,
I usually apply following steps before going to preconditioners;
- Construct a smaller matrix and examine the nonzeros, try to use permutations
to get a smaller bandwidth (minimum degree or symrcm).
- Use symmetric diagonal scaling, which usually helps a lot but mostly not
enough by itself.
- I have found out that (as a part of my master thesis), ParaSails is a good
general purpose preconditioner and you can have symmetric ParaSails
preconditioners easily.
I hope this helps.
Regards,Abdullah Ali Sivas
