dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

kent-and@xxxxxxxxx wrote:
> > kent-and@xxxxxxxxx wrote:
> > > > One or more new changesets pushed to the primary dolfin repository.
> > > > A short summary of the last three changesets is included below.
> > > >
> > > > changeset:   4730:6548c25c33352492c9279c035509a139caab323b
> > > > tag:         tip
> > > > user:        "Garth N. Wells <gnw20@xxxxxxxxx>"
> > > > date:        Tue Sep 09 13:08:58 2008 +0100
> > > > files:       dolfin/fem/Assembler.cpp dolfin/pde/LinearPDE.cpp
> > > > description:
> > > > Revert to old assembly in LinearPDE due to bug in symmetric assembly.
> > > >
> > > > There is a problem with exterior facets in the symmetric assembly. The
> > > > code needs to be broken up to make debugging easier.
> > > Agree that it should be broken up. But it will take some effort.
> > > Do you have an example where the bug is apparent ?
> > I was using a RT0 element (not one of the demos).  It should be
> > reproducible by adding a non-zero Dirichlet bc (given be a Function) to
> > the mixed-poisson demo.
> >
> > I had a quick look, but I couldn't find the problem, so I thought it
> > better to wait until the code is broken up.
> >
> > Garth
>
> Strange, I see no reason for this not to work.
> (since the code involving only cell integrals is pretty clean, but ...)
>
> Anyway, I noticed that with my setup, CG is used. CG can not be used
> in this case since the problem is not positive. Did you use CG ? 

No, I used an LU solver. I first noticed the problem when the LU solvers 
return a message that the system was singular. I only looked at the 
computation of the RHS vector which was zero when it  shouldn't have been.

The application of bcs on external is within the loop over all cells. 
Shouldn't it be within a loop over all boundary cells?

Garth

Did
> it converge (and does this really mean convergence in the usual sense) ?
>
> Kent