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.joli...@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