dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, Aug 13, 2008 at 06:31:22PM +0200, kent-and@xxxxxxxxx wrote:
> 
> > Kent-Andre Mardal wrote:
> >> BTW: the Assembler code that computes A, b and enforces BC
> >> simultaneously in a symmetric way,
> >
> > Very nice. We can now implement some symmetric linear solvers.
> >
> > Do you keep the 'Dirichlet' dofs and zero the row and column, or do you
> > eliminate them from the global system?
> 
> The Dirichlet dofs are kept. I thought that was simplest to do..
> >
> > is now faster than the standard
> >> non-symmetric way of doing it:
> >>
> >> timings:
> >> new     : 1.55
> >> standard: 1.94
> >>
> >
> > Which backend is this using? It could be saying more about the
> > efficiency of the function ident(..), which I suspect is slow for
> > uBlasMatrix, than the assembly process.
> >
> 
> Good point. There is speed up for all backends that I have tried.
> Here are the numbers:
> 
>  ~/local/src/dolfin/demo/pde/sym-dirichlet-bc >python speed-up-test.py  |
> grep using
> time for standard assembly  1.89726901054  using  uBLAS
> time for new assembly       1.49513792992  using  uBLAS
> time for standard assembly  1.97571492195  using  PETSc
> time for new assembly       1.55099701881  using  PETSc
> time for standard assembly  2.26576018333  using  Epetra
> time for new assembly       1.86703896523  using  Epetra
> 
> 
> Kent

Very nice. Is assemble_system fully working now? Can it be safely used
for all forms (in particular DG forms)? If so, we can start using it
in LinearPDE::solve().

-- 
Anders

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