[petsc-dev] Can MATAIJ support block size?

Smith, Barry F. bsmith at mcs.anl.gov
Thu Sep 20 15:15:09 CDT 2018

  Not a priority for us but if you implement clean code to do this we're likely to accept it.


> 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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