[petsc-users] how to switch ILU to its block version?

[Matthew Knepley]

On Sun, Mar 1, 2015 at 4:55 PM, Fande Kong <fd.kong at siat.ac.cn> wrote:

> Thanks, Barry.
>
> More questions. Is bs usually the number of unknowns associated with a
> grid point. Do I need to change MatSetValues if use a MATSEQBAIJ matrix?
>

No, but it does enable you to use MatSetValuesBlock() if you want.

   Matt


> Fande,
>
> On Sun, Mar 1, 2015 at 2:36 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>>
>>   Fande,
>>
>>     The MATSEQBAIJ matrix automatically uses a point block ILU; with the
>> block size of the matrix. So if your matrix naturally has a block size bs
>> if you use the MATSEQBAIJ matrix type it will be point block ILU of block
>> size bs.
>>
>>     We don't have a variable point block ILU in PETSc for SeqAIJ. It is
>> possible to write but would be rather involved.
>>
>>    Barry
>>
>> > On Mar 1, 2015, at 1:47 PM, Fande Kong <fd.kong at siat.ac.cn> wrote:
>> >
>> > Hi all,
>> >
>> > I have a code with ILU as subdomain solver, and it works well. Now I
>> want to try a block version of ILU, there are some easy ways to implement
>> this?
>> >
>> > Fande,
>>
>>
>>
>


-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
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