ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Dec 01, 2009 at 09:41:04AM +0100, Marie Rognes wrote:
> Anders Logg wrote:
> >On Tue, Dec 01, 2009 at 09:15:53AM +0100, Marie Rognes wrote:
> >>Anders Logg wrote:
> >>>On Mon, Nov 30, 2009 at 11:01:59PM +0000, Garth N. Wells wrote:
> >>>>Anders Logg wrote:
> >>>>>We still haven't decided on the correct strategy for choosing the
> >>>>>degree of an unspecified element.
> >>>>>
> >>>>>What we have now looks at the total degree of the form and then sets
> >>>>>the degree accordingly. This doesn't really work weoull and the reason
> >>>>>is quite simple: We can't figure out the total degree correctly if we
> >>>>>don't know the degree of the coefficient.
> >>>>>
> >>>>>So my new suggestion is the following. We simply scan all elements in
> >>>>>the form with specified degrees and set the degree to the maximum
> >>>>>degree among the elements.
> >>>>>
> >>>>Or should it be the maximum degree of the test and trial functions?
> >>>Yes, that's basically what happens now. It looks at everything that
> >>>has a degree so it looks at the test and trial functions but also at
> >>>any coefficients that may happen to have a degree.
> >>>
> >>>That's useful for say v*f*g*dx if one of f and g happen to have a
> >>>degree specified. Then the degree for the other needs to be the same.
> >>>
> >>Why?
> >
> >Since that's how the generated quadrature code works. It loops over
> >quadrature points for an integrand and then it's useful if everything
> >in the integrand is evaluated at those points.
> >
>
> Ok.

I have made a new change of the selection strategy.

For quadrature, FFC now looks at the maximum degree of anything in the
form (including test and trial functions and coefficients).

For tensor representation, FFC first looks at the maximum degree to
select the degree but then looks at the total degree to select the
quadrature it uses at compile time.

I think this looks ok now and both FFC and UFL are ready for a new
release. There's still the bug fix Kristian is working on for using
quadrature elements for coefficients instead of Lagrange, but we
don't need to wait with the release.

FFC is still verbose about its selection of degrees so keep an eye on
what FFC prints during compilation and report any strange behavior.

--
Anders

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