[petsc-dev] Solving systems with (K,M)AIJ

[Barry Smith]

  Pierre,

    This is not what you want but has the same flavor PCHMG. Here all the fields are in one giant matrix, it builds a preconditioner for a single field and then reuses it for all the fields. 

    I think people have to start writing custom preconditioners for the structure of (K,M)AIJ matrices but I don't think anyone has started that yet.

   Barry




> On Jun 23, 2020, at 1:16 AM, Pierre Jolivet <pierre.jolivet at enseeiht.fr> wrote:
> 
> Hello,
> When solving systems with a KSP that has a (K,M)AIJ Pmat attached to it, it may be nice to define a preconditioner on the inner AIJ Pmat, so that we are not stuck with PCPBJACOBI.
> For example, with FS, there is PCFieldSplitGetSubKSP and then you do what you want with the inner blocks.
> Is there something similar for (K,M)AIJ, maybe with a fancy PCCOMPOSITE?
> Of course, I could simply write a shell, but a new PC/option could be added to deal with such Pmat types?
> 
> Thanks,
> Pierre