[dune-pdelab] bug/problem in set_trivial_row function routine(dune-pdelab)

[Nagaiah Chamakuri]

Dear Felix Heimann,
Thank you for your response. I am sorry to say that I did not give complete
details.
you are right. I am referring vector valued solution which can be
represented by PowerGridFunctionSpace in PDELab.
I know only that we can set physical boundary conditions (Neumann or
Dirichlet BC's)
using Dune::PDELab::constriants() function. I do not know that we can impose

constraints (artificial BC) for ghost elements as well. Also, I am not sure
how to set the constraints
for ghost elements in this constraints() function.

Is it a good idea to set artificial boundary conditions for ghost elements
in non overlapping grids case using Dune::PDELab::constraints(..)?
I would expect that these atrificial boundary conditions should be
automatically taken care by
gridoperator function routines. am I stupid here or did not understand
parallel pdelab routines properly?

Thank you in advance.

Best Regards
Nagaiah



On Fri, Jan 14, 2011 at 4:46 PM, Felix Heimann <
felix.heimann at iwr.uni-heidelberg.de> wrote:

> Dear Nagaiah,
>
> I am not sure, what exactly you mean by "more than one solution
> component". If you refer to e.g. a vector valued solution, then this
> should be represented by e.g. a PowerGridFunctionSpace. In such a case,
> the set_trivial_row() function will work correctly as long as the
> indices in the constraints container are consistent to the indices of
> the grid function space (this should be guaranteed if you set up the
> container with the Dune::PDELab::constraints(..) function).
>
> However, this functionality is the same for all trivially constrained
> dofs, independent of whether they result from a ghost cell in a domain
> decomposed non-overlapping application or a Dirichlet boundary in a
> standard application. Hence, I do not see the connection to the specific
> grid i.e. application and may not have grasped your problem. May be you
> can clarify...
>
> Best Regards,
> Felix Heimann
>
>
>
> Am Mittwoch, den 12.01.2011, 22:57 +0100 schrieb Nagaiah Chamakuri:
> > Dear dune-pdelab,
> >
> > I have a question about "set_trivial_row" function in
> > new_gridoperatorspace.hh at line 885  (precisely I am using Jacobian
> > function routine to construct matrices) and defined in
> > gridoperatorspaceutilities.hh at line 971.
> > Mainly I am using non overlapping grid (UG grid) and diagonal elements
> > of the ghost nodes are set to zero in the global matrix
> > in case of more than one solution component presents.
> > This function routine works well in case of one solution component
> > presents in the problem.
> >
> >
> > right answer should look like as follows (up to my knowledge):
> >
> > for j=1 to no.of.comp
> > B::clear_row(i+j,globalcontainer)
> >
> > B::access(globalcontainer,i+j,i+j) = 1,
> >
> >
> >
> > Is it right? or  didn't I understand correctly?
> >
> > Thanks & Regards
> > Nagaiah
> > _______________________________________________
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> > dune-pdelab at dune-project.org
> > http://lists.dune-project.org/mailman/listinfo/dune-pdelab
>
> --
> Felix Heimann
> Universität Heidelberg
> Interdisziplinäres Zentrum für Wissenschaftliches Rechnen
> Arbeitsgruppe Paralleles Rechnen
> IWR 368, Raum 422
> Tel: 06221 / 54 8881
>
>
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>



-- 
Dr. Chamakuri Nagaiah
Institute of Mathematics and Scientific Computing
Heinrichstrasse-36, University of Graz,
A-8010, Graz, Austria. Ph(office) : (0043) 316 380 5063
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