dolfin team mailing list archive

["Johan Hoffman" <jhoffman@xxxxxxxxxx>]

That's great! Then of course we should use that somehow.

> There is a "trace_tabulate" method in FIAT that computes the values
> of the basis functions on a boundary facet (or the interior, if you
> like), FFC should make use of that and then throw away things that
> are zero.
>
>
> On Apr 12, 2006, at 10:22 AM, Johan Hoffman wrote:
>
>> Ok, good to know. Any ideas on what would be the best solution?
>>
>> /Johan
>>
>>
>>> You most definitely don't want to use the d-1 dimensional element of
>>> the same type.  Works great for Lagrange (and actually Hermite, for
>>> what it's worth), but is disastrously catastrophic for everything
>>> else.
>>>
>>>
>>> On Apr 12, 2006, at 8:29 AM, Garth N. Wells wrote:
>>>
>>>> On Wed, 2006-04-12 at 15:09 +0200, Garth N. Wells wrote:
>>>>> On Wed, 2006-04-12 at 14:30 +0200, Johan Hoffman wrote:
>>>>>
>>>>>> Apart from the issue of duplicating code with or without
>>>>>> templates, what
>>>>>> do we need to figure out to get the assembly of boundary integrals
>>>>>> correct?
>>>>>>
>>>>>> Do we have a clear way to obtain the FE basis for the boundary of
>>>>>> a cell
>>>>>> given the basis of the cell? Do we use the corresponding basis
>>>>>> for for d-1
>>>>>> dimensions?
>>>>>>
>>>>>> /Johan
>>>>>>
>>>>>
>>>>> This will have to come from FFC won't it? It might be less
>>>>> efficient,
>>>>> but we could work with the finite element of the whole cell and
>>>>> perhaps
>>>>> the edge/face number is enough for FFC to do the rest.
>>>>
>>>> Thinking about this some more, it might be better not to restrict
>>>> the
>>>> finite element basis to the boundary in order to work with problems
>>>> where derivatives of the basis functions appear in the boundary
>>>> integrals, and hence involve all nodes of the element. Similar
>>>> story for
>>>> non-conforming elements.
>>>>
>>>> Garth
>>>>
>>>>
>>>>> I noticed that
>>>>> the FFC-produced function eval takes "unsigned int boundary" as an
>>>>> argument, but doesn't do anything with it yet.
>>>>>
>>>>> Garth
>>>>>
>>>>>
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