dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Anders Logg wrote:
> On Tue, Oct 21, 2008 at 04:45:01PM +0100, Garth N. Wells wrote:
> > I have a few questions and thoughts regarding the new Function design
> >
> > * It's not clear to me what the intention is with user-defined 
> > functions. The functions Function::interpolate(...) never call eval(..), 
> > so they can't pick up user-defined values. Should Function::interpolate 
> > test for the presence of a GenericVector to decide whether or not the 
> > Function is discrete or user-defined?
>
> Yes, sorry. I've missed this. I'll fix it.
>
> > * It would be useful to declare user-defined functions without 
> > associating a FunctionSpace. If we want to interpolate the function, a 
> > FunctionSpace must then be provided. Anyone see any problems with this?
>
> The reasoning here is that all Functions must always be associated
> with a FunctionSpace so that they may be correctly interpreted in
> forms and correctly plotted. When a Function is created in PyDOLFIN,
> it must always be associated with a certain FiniteElement (and in a
> while FunctionSpace). It would simplify the handling of Functions if
> they are always associated with a FunctionSpace.

Something else to think about is that user-defined functions don't have 
a dof map, so we need can't initialise a FunctionSpace with the present 
FunctionSpace constructors.

Garth

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