dolfin team mailing list archive

[Kent-Andre Mardal <kent-and@xxxxxxxxx>]

On 4 October 2011 18:13, Anders Logg <logg@xxxxxxxxx> wrote:

> On Tue, Oct 04, 2011 at 04:17:01PM +0100, Garth N. Wells wrote:
> > On 4 October 2011 12:24, Anders Logg <logg@xxxxxxxxx> wrote:
> > > SystemAssembler does not support subdomains. It is even silently
> > > ignoring all other integrals than number 0.
> > >
> > > This is one of the remaining bugs for 1.0-beta2. I can try to fix it
> > > but would like some input on what shape the SystemAssembler is
> > > currently in. I haven't touched it that much before since it looks
> > > like a bit of code duplication to me. In particular, is it necessary
> > > to keep both functions cell_wise_assembly and facet_wise_assembly?
> > >
> >
> > It would require some performance testing to decide. I expect that,
> > for performance reasons, both are required.
>
> I'm getting very strange results. Here are results for assembling
> Poisson matrix + vector on a 32 x 32 x 32 unit cube:
>
>  Regular assembler: 0.658 s
>  System assembler:   9.08 s (cell-wise)
>  System assembler:    202 s (facet-wise)
>
> Is this expected?
>
> What are the arguments against ditching SystemAssembler (for less code
> duplication) and adding functionality for symmetric application of BCs
> on the linear algebra level?
>
>


Earlier system_assemble of A and b was faster than assemble of A and b.
Something strange must have happened.

SystemAssemble enforce symmetric BC elementwise which
is much faster than doing it on linear algebra level.

Kent


> --
> Anders
>
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