[petsc-users] Field split questions

[Matthew Knepley]

On Wed, Aug 8, 2012 at 10:51 PM, Matthew Knepley <knepley at gmail.com> wrote:

> On Wed, Aug 8, 2012 at 10:23 PM, Colin McAuliffe <cjm2176 at columbia.edu>wrote:
>
>> Thanks all, regarding use of DM in 3.3, is the procedure now to create
>> the fields with PCFieldSplitSetIS and then use DMCreateFieldDecompositionDM
>> to create a new DM based from the new fields and the DM for the original
>> problem?
>>
>
> 1) Use petsc-dev
>
> 2) PCFieldSplitSetIS() is independent. This allows you to define splits
> however you want, but then recursive gets harder
>
> 3) In 3.3., it uses DMCreateFieldDecompositionDM() to split all fields
> apart at once
>
> 4) In petsc-dev, it uses DMCreateSubDM() which can split off any
> combination of fields, which from the command line is something like
>
>      -pc_fieldsplit_0_fields 2,0 -pc_fieldsplit_1_fields 1,3
>

I should have shown recursive:

  -fieldsplit_0_pc_type fieldsplit

will split 2,0 into two blocks.

   Matt


>      Matt
>
>
>> Colin
>>
>> --
>> Colin McAuliffe
>> PhD Candidate
>> Columbia University
>> Department of Civil Engineering and Engineering Mechanics
>>
>
>
>
> --
> 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
>



-- 
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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