dolfin team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

Anders Logg wrote:
> On Fri, Feb 02, 2007 at 09:32:13PM +0100, Garth N. Wells wrote:
> > Anders Logg wrote:
> > > On Fri, Feb 02, 2007 at 02:46:35PM +0100, Johan Hoffman wrote:
> > > > > Johan Hoffman wrote:
> > > > > > About the global dof numbering for the different components in a
> > > > > > function
> > > > > > defined by a mixed element: I get the impression that we use a different
> > > > > > ordering for the mixed dofs than for the dofs of a regular vector valued
> > > > > > function?
> > > > > I don't think so. For both mixed and vector elements, dofs at the same
> > > > > node do not lie next to each other in the dof mapping.
> > > > >
> > > > > It will be possible to choose the dof ordering soon when the new
> > > > > assembly is  up and running. There is already a new class DofMap which
> > > > > will handle this.
> > > > >
> > > > > Garth
> > > Generally, you can never be sure how the dofs are ordered. This could
> > > potentially change between different versions of FFC or between
> > > different form compilers. As long as the generated code follows the
> > > UFC specification, the dof maps may be different.
> > This sounds strange. DofMap will provide the functionality to influence 
> > the dof mapping. UFC should provide the input to DofMap, but the user 
> > should then be able to manipulate it if they wish.
>
> I don't mind documenting how FFC actually orders the dofs, but the
> idea of the UFC interface is that one should not need to know intimate
> details of FFC to work with the generated code.

What I'm trying to say is that a user should be able to influence the 
dof mapping through the public member functions of dolfin::DofMap. They 
don't need to know the details of FFC, or even UFC.

Garth

> /Anders
> _______________________________________________
> DOLFIN-dev mailing list
> DOLFIN-dev@xxxxxxxxxx
> http://www.fenics.org/mailman/listinfo/dolfin-dev