dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, Apr 27, 2011 at 03:24:05PM +0200, Martin Sandve Alnæs wrote:
> On 27 April 2011 12:38, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
>
>
>
>     On 27/04/11 11:08, Kristian  lgaard wrote:
>     > On 27 April 2011 11:52, Anders Logg <logg@xxxxxxxxx> wrote:
>     >> On Wed, Apr 27, 2011 at 10:40:50AM +0100, Garth N. Wells wrote:
>     >>> We need a quick discussion round to resolve this issue - DOLFIN is now
>     >>> broken. I guess we need the form compiler to decide on the cell and
>     >>> element type, and then have UFL return a new form.
>     >>
>     >> Yes, Martin mentioned at some point that it would be easy to add such
>     >> a function to UFL (that takes a form and replacement elements and
>     >> returns a new form).
>     >>
>     >> Martin, could you add such a function?
>
>
> I started some time before easter, but as Garth says...
>
>
>     > I think ufl.algorithm.transformations.replace would work if
>     > FiniteElementBase derived from 'Terminal'.
>     > Currently, it derives from 'object', what is the reason for that?
>     > Anyway, it should be simple enough to add something equivalent for
>     elements.
>     >
>
>     I was thinking that we only need to replace Coefficients, e.g. if a
>     Coefficient is defined using an 'incomplete element', FFC can create an
>     element, a Coefficient and the perform the replacement. Looks like UFL
>     can do this already.
>
>     The problem from the DOLFIN side is that the new UFL Coefficient will be
>     different from the DOLFIN/UFL Coefficient, and would be a
>     ufl.Coefficient and not a dolfin.Coefficient.
>
>
> ... this may be a problem. Since I don't really know the motivation for this
> feature request, I can't solve this problem for you.

The motivation is that we want to accomplish what we now accomplish
with the set_cell/degree functions that you have decided to remove.

This allows us to write f = Expression("sin(x[0])") and let the form
compiler choose a suitable approximation for the expression.

--
Anders





> Martin
>
>
>
>
>     Garth
>
>     > Kristian
>     >
>     >>
>     >>
>     >>> Garth
>     >>>
>     >>> On 26/04/11 07:32, noreply@xxxxxxxxxxxxx wrote:
>     >>>> ------------------------------------------------------------
>     >>>> revno: 1014
>     >>>> committer: Martin Aln s <martinal@xxxxxxxxx>
>     >>>> branch nick: ufl
>     >>>> timestamp: Fri 2011-04-15 21:44:37 +0200
>     >>>> message:
>     >>>>   Add warnings to set_foo functions in finiteelement.py,
>     >>>>   and remove repr modifications after construction time.
>     >>>>
>     >>>>   If this will break your code, it likely wasn't working
>     >>>>   correctly anyway and you need to rewrite it before you
>     >>>>   can update to this UFL version.
>     >>>>
>     >>>>   The set_foo functions will be removed completely before UFL 1.0.
>     >>>>
>     >>>>   Happy easter holiday :)
>     >>>> modified:
>     >>>>   ufl/finiteelement.py
>     >>>>
>     >>>>
>     >>>
>     >>>
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>     >>
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>
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