dolfin team mailing list archive

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

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.

Garth

> This means that it is very important that everything you need to know
> about the generated code is covered by the UFC specification.
>
> I will post on a related subject (ufc::finite_element::sub_element)
> in a while to ufc-dev.
>
> /Anders
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