[petsc-dev] Can MATAIJ support block size?

Fande Kong fdkong.jd at gmail.com
Thu Sep 20 16:29:10 CDT 2018

Thanks Barry,

I am going to take a try.


On Thu, Sep 20, 2018 at 2:15 PM Smith, Barry F. <bsmith at mcs.anl.gov> wrote:

>   Not a priority for us but if you implement clean code to do this we're
> likely to accept it.
>    Barry
> > On Sep 20, 2018, at 12:27 PM, Fande Kong <fdkong.jd at gmail.com> wrote:
> >
> > Hi Developers,
> >
> > MATBAIJ actually assumes that the point-block is dense. It is fine if
> the block size is small for example less than 50, but we may suffer from a
> memory issue if the block is large such as 1000. The block is not necessary
> dense. In my application, neutron transport equations, the block is
> actually sparse (coming from direction and energy grids).  Now I am using
> MATAIJ, but I want to take into consideration there are many variables on
> each spatial grid when doing some ILU(0).  ILU(0) is used as a subdomain
> solver for ASM and BJACOBI.
> >
> > I would like to support point-block ILU(0) in MATAIJ (not MATBAIJ)
> because the block is sparse. Any comments? It is worthwhile to do that? I
> think we might reduce the symbolic factor time when considering the block.
> >
> > Thanks,
> >
> > Fande,
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