dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Feb 18, 2008 at 04:35:54PM +0100, Johan Hoffman wrote:
> > This is good juncture at which re-focus on important goals for a
> hopefully not too distant next release. Three priorities that I see are:
> >
> > - New build system.
> >
> > - Improved support for parallel assembly and solve. The class Function
> will probably need the most work. Good goals would be to get Poisson and
> elasticity demos running in parallel.
> 
> I thought the Poisson problem was running, and showing good parallel
> scaling? Or maybe that was a test outside the dolfin-dev demos?

The demo is in src/demo/fem/assembly/.

> We (Nicklas) have now a preliminary distributed parallel implementation
> running for Poisson and a Unicorn flow solver. The structure is still
> quite messy and the partitioning is based on Metis, but we expect it to be
> integrated with DOLFIN in the coming months, hopefully before the
> summer.

Could this be done in small pieces? I'm a little worried about seeing
big changesets that add things to the mesh classes.

> When the structure is more clear we can discuss on the mailing list how to
> best incorporate this into DOLFIN. Apart from the structure of the
> implementation we are also focusing on distributed local mesh refinement.

Great.

What is the difference from what we have now? Is it the same but with
a distributed mesh (so each processor just sees the local part, not
the whole mesh)? Or is it something different?

I think what we have now can be fairly easily extended to a
distributed mesh without any (significant) changes to the mesh
classes. The key point is to build the DofMap in parallel. Take a look
here, in particular Section 6 and Algorithm 5:

  http://simula.no/research/scientific/publications/Simula.SC.75

> > - Testing of QuadratureFunction and adding corresponding demos.
> >
> > Another point is to add Trilinos as a supported linear algebra back end.
> How does this tie up with closer links to PyCC?
> >
> > Garth
> 
> - Something else that I think is important is to include geometry in
> DOLFIN. We were to start such a project before Christmas, but we lost the
> msc student that was supposed to work on this. I would expect that we
> restart this later this spring. Basically we need to import CAD-geometry
> (or other geometry descriptions), create an internal DOLFIN format
> (typically based on NURBS or similar) with a Geometry-class. Typical
> functionality needed is then to project a point onto the surface geometry.

That would be nice.

-- 
Anders


> /Johan
> 
> 
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