dolfin team mailing list archive

["Johan Hoffman" <jhoffman@xxxxxxxxxx>]

In connection with the dof-discussion; could we add geometry info to FFC?
Like diameter, normals, tangents etc. From what I understand this info is
already in FIAT, so it would amount to adding a mapping to FFC?

/Johan




> Anders Logg wrote:
>> On Mon, Dec 04, 2006 at 02:14:51PM +0100, Garth N. Wells wrote:
>>> Could we add something to FFC to describe where the various degrees of
>>> freedom live (on vertices, edges, internal)?
>>>
>>> Garth
>>
>> Yes we could, but I'd rather not. Why do we need it? I'd prefer if
>> DOLFIN did not know anything about dofs, other than how to reorder
>> them.
>>
>
> Not sure that it's this simple if you want to assemble some terms
> block-wise. Also, for parallel assembly we might need to know where dofs
> lie. I'm still thinking about this so I can't be concrete in what's
> needed just yet.
>
>> I see two options:
>>
>>  1. Reorder the dofs computed by FFC, not knowing why and how they
>>     are numbered.
>>
>
> This is one option I'm considering. Just take the FFC numbering, and run
> a renumbering algorithm over it to minimise bandwidth.
>
>>  2. Compute a different mapping in FFC.
>>
>
> This could be difficult as it depends on properties of the mesh,
> partition, etc. I think that this should remain simple.
>
>> I can be convinced otherwise of course, but I don't understand why
>> this is needed.
>>
>> /Anders
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>
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