ffc team mailing list archive

[Marie Rognes <meg@xxxxxxxxx>]

Kristian Oelgaard wrote:
> 2010/1/27 Medhi Nikbakht <m.nikbakht@xxxxxxxxxx>:
> > On Wed, 2010-01-27 at 15:50 +0100, Marie Rognes wrote:
> > > FFC compilation fails for
> > >
> > >     ElementRestriction.ufl
> >
> > The error message says that "ElementRestriction" is not supported by
> > FIAT.
> > How will the restricted elements be implemented? Wouldn't it be better
> > to support them inside FFC?
>
> There are two types of restrictions supported in UFL (and the old FFC).
> 1) Restriction onto Measure (like 'dc'), which is what you want.
> 2) Restriction onto Cell, as for instance restricting a Lagrange 
> element defined on a 'triangle' to its facets.
>
> The third restriction that we might want in the future is restriction 
> onto subdomains possible in UFL but not in FFC.
>
> To implement 1) I think it is enough to just attach the Measure as a 
> member to the fiat_element and the simply look for it in appropriate 
> places when generating the code. That means handle it in 
> FFC.fiatinterface, could that work?
>
> To implement 2) I modified the return value of entity_dofs() and 
> tabulate() accordingly. To do it this way again we will need to make 
> changes in FIAT_NEW.FiniteElement and FFC.MixedElement. I'm not sure 
> it is a good idea to make FIAT_NEW.PolynomialSet aware of 
> restrictions, but I don't know enough about the FIAT internals to back 
> up this claim.


How about adding a class RestrictedElement that contains an element and 
(based on the restriction)
a list of relevant basis function indices, and overrides the methods as 
FiniteElement/MixedElement?

No need to make FIAT aware of this.

--
Marie


> I'm not really sure how to handle the restriction onto subdomains, but 
> it should most likely be implemented in FFC.
>
> Kristian
>
> > Mehdi
> >
> > >     QuadratureElement.ufl
> > >     TensorWeightedPoisson.ufl
> > >
> > > Running test programs fails for
> > >
> > >     P5tet.bin    (Segmentation faults after evaluate_basis(0, ...)
> > >
> > > Differences in output
> > >
> > >     evaluate_basis*
> > >
> > >     FacetIntegrals.out      (missing value in generated code (many))
> > >     SubDomain.out            (missing value in generated code
> > > (tabulate_tensor))
> > >
> > >
> > > Others:
> > >
> > >     tabulate_entity_dofs     (errors thrown are all wrong. Marie 
> > > will fix)
> > >
> > >
> > > --
> > > Marie
> > >
> > >
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