dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Nov 03, 2008 at 02:44:41PM +0000, Garth N. Wells wrote:
> 
> 
> Anders Logg wrote:
> > On Mon, Nov 03, 2008 at 01:04:26PM +0000, Garth N. Wells wrote:
> >> DOLFIN wrote:
> >>> One or more new changesets pushed to the primary dolfin repository.
> >>> A short summary of the last three changesets is included below.
> >>>
> >>> changeset:   5080:89eb83718857c7d9dbee0003a50983e28533243e
> >>> tag:         tip
> >>> parent:      5079:34987a77383c6b8a37a9c73d40ba4dc38115ca97
> >>> parent:      5078:1182f3401713488f72e0bc52f8031530bf192bd9
> >>> user:        Anders Logg <logg@xxxxxxxxx>
> >>> date:        Mon Nov 03 13:57:42 2008 +0100
> >>> files:       dolfin/fem/DirichletBC.cpp
> >>> description:
> >>> merge
> >>>
> >> Beat me to it.
> >>
> >> I'm running into an issue with DirichletBC and mixed elements because 
> >> BoundaryCondition, from which DirichletBC inherits, creates a new 
> >> FunctionSpace which messes up tests for equivalence and breaks the 
> >> sharing of function spaces paradigm.
> >>
> >> Is there a problem if we remove SubDomain from the argument list for 
> >> DirichletBC and just pass the corerct FunctionSpace? One can easily 
> >> extract the necessary sub element FunctionSpace and send it to 
> >> DirihcletBC. To me this is more intuitive.
> >>
> >> Garth
> > 
> > We then need to find a nice way for users to extract the "sub space".
> > Calling extract_sub_space, getting a pointer and then handling the
> > deletion of that pointer won't look very nice.
> > 
> 
> Agree. So we remove the SubSystem argument to DirichletBC?

Yes.

> > How about replacing the SubSystem class with a new class SubSpace
> > which works just like SubSystem but it also inherits from
> > FunctionSpace:
> > 
> >   SubSpace Vu(V, 0);
> >   SubSpace Vp(V, 1);
> > 
> 
> Looks ok. I'm inclined to keep the name SubSystem because what we're 
> extracting are not really subspaces.
> 
> Garth

I also thought about that, but came to the conclusion that in some
sense it is in fact a subspace. For example, for 2D Stokes Vu above
will be the subspace of all function which have a zero third component
(although the third component is not written out).

We could possibly name it SubSystemSpace.

-- 
Anders

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