dolfin team mailing list archive

[Shawn Walker <walker@xxxxxxxxxxxxxxx>]

So, when you do

mesh.refine()

that automatically replaces the old mesh with the new one?  This seems ok. 
As long as the user still has the option of storing the old unrefined mesh 
and associated functions.

How will functions be updated?  Just interpolation?  Is that easy to do if 
you use some non-standard elements, i.e. H(div), etc...  I guess the 
question is this:   Is there a unique way to update the functions?  If so, 
then this should be safe.  If not, then there might be headaches with 
this...

- Shawn

On Mon, 2 Nov 2009, Anders Logg wrote:

> I've thought some more on the problem of mesh refinement and updating
> of Functions.
>
> The main problem seems to be the following:
>
>  mesh.refine()
>
> If we want to allow this, then we need to provide some kind of
> automated updating of functions and function spaces to the new mesh,
> since this call will otherwise destroy all function spaces and
> functions that refer to that mesh:
>
>  V = FunctionSpace(mesh, "CG", 1)
>  v = Function(V)
>  mesh.refine() # V and v no longer make any sense
>
> This gives us two options. Either we disallow refinement of a mesh
> without making a copy. Or we provide automated updating. I think we
> should do the latter.
>
> What is needed compared to what we have now is to let a call to
> Mesh::refine trigger a call to FunctionSpace::update for all function
> spaces defined on the mesh, which in turn will trigger calls to
> Function::update for all functions defined on the function spaces.
>
> We can make the update functions private.
>
> Comments or objections? I think I can make this work.
>
> --
> Anders