[petsc-dev] plans for preconditioners for SeqSELL

[Zhang, Hong]

> On Feb 12, 2018, at 8:36 AM, Jed Brown <jed at jedbrown.org> wrote:
> 
> Karl Rupp <rupp at iue.tuwien.ac.at> writes:
> 
>> Hi Stefano,
>> 
>>> Is there any plan to write code for native ILU/ICC etc for SeqSELL, at least to have BJACOBI in parallel?
>> 
>> (imho) ILU/ICC is a pain to do with SeqSELL. Point-Jacobi should be 
>> possible, yes. SELL is really just tailored to MatMults and a pain for 
>> anything that is not very similar to a MatMult...
> 
> There is already MatSOR_*SELL.  MatSolve_SeqSELL wouldn't be any harder.
> I think it would be acceptable to convert to SeqAIJ, factor, and convert
> the factors back to SELL.

This is feasible. I will give it a try when I have time. Another option that works now is to use two matrices with different Mat types, e.g. aij for the preconditioner and sell for Jacobian.

Hong (Mr.)