ffc team mailing list archive

[Johan Hake <hake@xxxxxxxxx>]

On Wednesday 19 August 2009 14:28:08 Johan Hake wrote:
> On Wednesday 19 August 2009 13:31:56 Garth N. Wells wrote:
> > Kent Andre wrote:
> > >> Not sure what we have to do actually. I suppose I want get any clue
> > >> from the
> > >>
> > >>   demo/function/restriction
> > >>
> > >> demo?
> > >>
> > >> I see that Kent has modified the dolfin.FunctionSpace to reflect the
> > >> present (broken) implementation of restriction, anything in that line?
> > >> Should such an implementation has been done in FunctionSpaceBase
> > >> instead of FunctionSpace? Kent?
> > >>
> > >> Johan
> > >
> > > This restriction is different in the sense that the restriction is made
> > > by the standard element on a sub mesh.
> > >
> > > The restriction in focus now is on the complete mesh but for only
> > > a part of the element.
> > >
> > > Combined, these two features will be very powerful.  I guess the
> > > sub-mesh restriction stuff is broken due to the parallel mesh.
> >
> > I've attached an example solver. To make it work for P^k with k > 2 we
> > need to restrict some functions to cell facets. Using FFC, we do
> >
> >      scalar  = FiniteElement("Lagrange", "triangle", 3)
> >      dscalar = FiniteElement("Discontinuous Lagrange", "triangle", 3)
> >
> >      # This syntax restricts the space 'scalar' to cell facets.
> >      mixed = scalar["facet"] + dscalar
> >
> > In PyDOLFIN we could do
> >
> >      V_dg = FunctionSpace(mesh, "DG", 3)
> >      V_cg = FunctionSpace(mesh, "CG", 3, "facet")
> >
> >      mixed = V_cg + V_dg
> >
> > or
> >
> >      V_dg = FunctionSpace(mesh, "DG", 3)
> >      V_cg = FunctionSpace(mesh, "CG", 3)
> >
> >      mixed = V_cg["scalar"] + V_dg
>
> I am inclined to go for alternative 1, 

sorry ment 2...

> but I am a bit confused what a
> restricted MixedFunctionSpace is, and what the supspaces of such a Space
> would be.
>
> Our FunctionSpace design in PyDOLFIN is a bit fragile so we need to think
> of a robust way to implement this.
>
>
> Johan
>
> > Garth
> >
> > > Kent
> > >
> > > _______________________________________________
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> > > DOLFIN-dev@xxxxxxxxxx
> > > http://www.fenics.org/mailman/listinfo/dolfin-dev
>
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