[petsc-dev] Attaching DMKSP/SNES/TS with PetscObjectCompose() change

[Barry Smith]

On Nov 30, 2012, at 11:30 AM, Matthew Knepley <knepley at gmail.com> wrote:

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> On Nov 30, 2012 11:17 AM, "Barry Smith" <bsmith at mcs.anl.gov> wrote:
> >
> >
> >    I would like to add to the _p_DM  struct
> >
> > PetscObject  dmksp, dmsnes, dmts.
> >
> >    The current model that uses PetscObjectCompose() is a mis-use of PetscObjectCompose(), why?
> >
> > The PetscObjectQuery() is always used for every function evaluation in every time step, every Newton step, …
> >
> > 1) this is a performance problem with small size ODEs for example
> >
> > 2) PetscObjectQuery is suppose to be for exceptional things that occur seldomly, not ones that occur inside the main computational routes.
> >
> >
> >
> >    Please send any technical (not philosophical) reasons why making this change is a bad idea and will haunt us later.
> 
> There is an extensibility problem that Jed has already noted.

    That is only a philosophical objection :-)  If one wishes to add a DMGetDMTAOSomething() they can implement it with the PetscObjectCompose() model so things are still extensible. 



    Barry

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>   Matt
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> >    Barry
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> >    
>