[petsc-dev] getting ready for PETSc release

[Jed Brown]

Matthew Knepley <knepley at gmail.com> writes:

> On Sat, Jun 7, 2014 at 5:11 PM, Jed Brown <jed at jedbrown.org> wrote:
>
>> Matthew Knepley <knepley at gmail.com> writes:
>>
>> > As far as I know, neither can do FV stuff which this is going to
>> > do.
>>
>> Where are your Riemann solve, characteristic reconstruction, and
>> boundary conditions interfaces?  You already used the generic namespace
>> for a volumetric term that doesn't even exist in FV formulations.
>
>
> Its in PetscFV. PetscProblem is supposed to hold both types. I can only work
> so fast, and I am doing the FEM example first.

So it's not supported by the PetscProblem interface?

>> > Maybe MOOSE does. However, neither of those has good integration with
>> > the solver (I have discussed this personally with Roy and Derek and
>> > they agree).
>>
>> You have to be able to formulate a similar scope of problems before you
>> get to argue fine points of supporting geometric multigrid and the like.
>> FWIW, it does not support the solve structure we use in pTatin so gives
>> up significant performance relative to existing packages that use solver
>> algorithms you want.
>>
>
> I asked you to help with this.

I pointed out that your interface can't do that algorithm and I showed
you code that can.  I'm not sure what you want me to do.  Change your
interface to be able to do that method fast, implying other data
structure changes and possible loss of functionality that you want?

>> >> think this belongs in PETSc, definitely not in such prominent namespace.
>> >>
>> >
>> > I don't know why you think this is so bad. I picked a name because I
>> needed
>> > a name. Its not DM, its a collection of DMs.
>>
>> It's a very framework-style name with generic connotations used for
>> something extremely specific.
>
>
> I do not think its for something that specific. It is to hold a
> collection of pointwise evaluation routines + discretizations. What is
> better than "problem"?

H^1 semi-discrete-in-time quadrature-based method of weighted residuals
without material models or boundary conditions.  "Problem" is way too
generic to be used for something so specific in PETSc.

>> >> I also cannot imagine that this interface is stable, so even if this
>> >> sort of thing goes into PETSc, there's no use having it in the release.
>> >>
>> >
>> > We have a bunch of stuff that is not completely stable. I am not sure
>> > what this kind of conservatism buys us.
>>
>> Exploratory programming in a release using a prominent namespace will
>>
>
> I think "prominent" here is misguided.

How else would you describe it?  I suggested
DMMattsCoolDiscretizationTSSetIFunctionVolumetricQuadrature().

>> encourage people to try using it, then have a bad experience when it (a)
>> does not work for their problem and (b) is changed soon after the
>> release.  I would rather that exploration happen in a different package
>> that users can opt into.
>>
>> I like developing library code in PETSc, and often look for ways to
>> formulate a new idea to make it appropriate for PETSc.  But some things
>> just make more sense in a separate package.  If there is a technical
>> problem with distributing such a package, we should solve that problem.
>>
>
> Its not a lot of code, its very useful for exactly the people that use
> our package, 

s/exactly the people/a subset of the people using H^1
semi-discrete-in-time quadrature-based method of weighted residuals
without material models or boundary conditions/

> it disrupts none of the existing workflow, and its got a fair number
> of test compared to other stuff we have released.

Deal.II has lots of tests.  Apart from the more restrictive license and
language choice, why don't we include it in PETSc?  It's currently more
flexible than your interface.  It can be a separate include so that it
does not disrupt existing workflow.
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