On 4 October 2011 19:21, Garth N. Wells <[email protected]> wrote: > On 4 October 2011 18:05, Kent-Andre Mardal <[email protected]> wrote: > > > > > > On 4 October 2011 18:13, Anders Logg <[email protected]> wrote: > >> > >> On Tue, Oct 04, 2011 at 04:17:01PM +0100, Garth N. Wells wrote: > >> > On 4 October 2011 12:24, Anders Logg <[email protected]> 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. > > It was faster because it was less general. After being generalised, > the performance of SystemAssembler was to all intents and purposes the > same as Assembler. > > > Something strange must have happened. > > SystemAssemble enforce symmetric BC elementwise which > > is much faster than doing it on linear algebra level. > > I'm not sure that that is true. In my experience the difference is > marginal. > > Garth >
ok, I think the reason for doing it elementwise is that I thought it was is easier and more efficient to go through the columns on the element level, but I might be wrong. Kent > > > Kent > > > >> > >> -- > >> Anders > >> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~dolfin > >> Post to : [email protected] > >> Unsubscribe : https://launchpad.net/~dolfin > >> More help : https://help.launchpad.net/ListHelp > > > > >
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