> > > [EMAIL PROTECTED] wrote: >>> [EMAIL PROTECTED] 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 <[EMAIL PROTECTED]>" >>>>> 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.
Ok, and I guess the system is singular unless you have a mix of essential and natural bc. But the rhs should not be zero. > > The application of bcs on external is within the loop over all cells. > Shouldn't it be within a loop over all boundary cells? In the present code I only run over each cell once. After the computations of the various integrals is performed, the BC is enforced. Kent _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
