[petsc-users] Create a DM given sets of IS's

[Stefano Zampini]

DMComposite?
https://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DM/DMCompositeCreate.html#DMCompositeCreate

Il giorno Lun 31 Dic 2018, 08:40 Justin Chang via petsc-users <
petsc-users at mcs.anl.gov> ha scritto:

> Hi all,
>
> I am solving a six field battery problem (concentration and potential for
> each of the two solid and one electrolyte domains) and I want to experiment
> with nested/recursice fieldsplitting. I have the IS's and am able to use
> these to define my PCFieldSplitsSetIS(). However, I can imagine this
> getting really messy from a programming standpoint, especially once I need
> to add temperature into the mix, so it is my hope that I can translate
> these index sets and fields into a DM (maybe DMShell?) so that I can just
> rely on command line options to play around with various combinations of
> field assignments and splits (e.g. -pc_fieldsplit_X_fields)
>
> However, it doesn't seem clear to me how I would create a DM when you
> already know the IS's for each fields. If I understand functions like
> DMCreateFieldDecomposition() correctly, it seems that it returns to you the
> IS's and sub DM's associated with the original DM, whereas I want to do it
> the other way around. Perhaps the "reversal" of something like
> DMCreateFieldIS()
> <https://www.mcs.anl.gov/petsc/petsc-dev/src/dm/interface/dm.c.html#DMCreateFieldIS>,
> where you convert the IS into a PetscSection or is there an easier/better
> way?
>
> Any thoughts/help appreciated!
>
> Justin
>
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