On Thu, Sep 11, 2008 at 03:02:36PM +0100, Garth N. Wells wrote: > > > Anders Logg wrote: > > On Thu, Sep 11, 2008 at 02:51:41PM +0100, Garth N. Wells wrote: > >> Martin Sandve Alnæs wrote: > >>> I don't agree, isn't the point that several DiscreteFunctions can > >>> share a FunctionSpace? > >>> > >> Yes, but a dof map doesn't define a function space. > >> > >> Garth > > > > I think the dof map should be in the FunctionSpace, that way several > > functions may share the dof map (which may take time to compute if we > > want to do some reordering). > > > > Two functions in the same function space share the mesh, the element > > and the dof map (these three define the space) but each function has > > its own vector. > > > > My point isn't that a DofMap won't shared, it's that it's not part of > the definition of a function space.
It is part of the function space if we say that a function space is
defined by a particular basis:
V = span{\phi_i}
To define the basis, we need the dof map.
> It always possible that two discrete functions which are equivalent can
> share a mesh and finite element (which defines the function space), but
> have different vectors and dof maps.
Is that something we will encounter much? It would simplify matters if
we said that a FunctionSpace is a function space with a particular
basis. We do that anyway if we include the finite element. Otherwise,
we could say that (P_1)^d and BDM_1 are the same function space, but
we think of them as different.
> > I added the FiniteElement class to avoid exposing ufc:: classes
> > directly. We do the same for ufc::dof_map (but then we have a reason).
> > It might not be necessary, but it looked more uniform to have
> >
> > (Mesh, FiniteElement, DofMap)
> >
> > instead of
> >
> > (Mesh, ufc::finite_element, DofMap)
> >
>
> Sure. I just can't find where FiniteElement is defined?
>
> Garth
I thought I had pushed it. It should be pushed now.
--
Anders
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