dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Sun, Aug 16, 2009 at 04:36:33PM +0100, Garth N. Wells wrote:
>
>
> Anders Logg wrote:
> > What is the reason for using int instead of uint in the precomputed
> > DofMap?
> >
>
> I didn't make it int, but I suspect that it is to leave open the
> possibility of using negative indexes which some libraries (e.g. PETSc)
> treat differently during insertion.

Negative indices will affect all backends. Does Trilinos support it?

> > Also, would it be good to have the same DofMapBuilder::build()
> > implementation both in parallel and serial. I imagine the algorithm
> > will specialize to the case of one process. This will be useful to
> > have once we add the localized iteration over cells on each mesh to
> > minimize bandwidth.
>
> DofMapBuilder::build() does not build the DofMap (name needs to be
> changed).

Yes, maybe DofMapRenumbering is better.

> It renumbers the dofs and is not required when running in serial.

I think it is. The FFC generated dof map does not do a very good job
at minimizing bandwidth for vector-valued elements (or even scalar
P2). I was hoping the same algorithm would work in both serial and
parallel (less code to maintain).

--
Anders


> I have added a FIXME (might not have pushed it yet) that
> DofMap::parallel_build needs to be broken into two functions. The first
> function should determine ownership of dofs when running in parallel,
> and the second does the re-numbering.
>
> Garth
>
> >
>
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