ufl team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Feb 16, 2009 at 10:09:55AM +0000, Garth N. Wells wrote:
> 
> 
> Kristian Oelgaard wrote:
> > Quoting "Garth N. Wells" <gnw20@xxxxxxxxx>:
> > 
> >>
> >> Anders Logg wrote:
> >>> On Mon, Feb 16, 2009 at 09:57:26AM +0100, Martin Sandve Alnæs wrote:
> >>>> On Sun, Feb 15, 2009 at 10:10 PM, Anders Logg <logg@xxxxxxxxx> wrote:
> >>>>> On Fri, Feb 13, 2009 at 02:30:00PM +0100, Martin Sandve Alnæs wrote:
> >>>>>> Attaching metadata to an integral is implemented, but we
> >>>>>> haven't  decided what format the metadata should be in.
> >>>>> I think there needs to be a convention as part of UFL for how to
> >>>>> specify the integration rule. Otherwise different form compilers will
> >>>>> invent different conventions and interpret the metadata differently.
> >>>> Agree.
> >>>>
> >>>>> Here's a suggestions:
> >>>>>
> >>>>>  metadata = ("quadrature", degree)
> >>>>>  metadata = ("tensor", degree)
> >>>> Here you're already into FFC territory...
> >>>>
> >>>> Integration order is an important mathematical
> >>>> property, the method for code generation is not.
> >>>> "tensor" is in the latter category.
> >>> Hints for the degree of the quadrature is also form compiler
> >>> specific. There may be other ways to evaluate the integral than
> >>> quadrature, for example by random sampling, symbolic integration (like
> >>> in SyFi) or using a tensor representation (FFC).
> >>>
> >> Tensor representation still uses quadrature, it's just that it's 
> >> performed a priori rather than at runtime.
> > 
> > I guess the degree is just the highest polynomial order that the user wishes
> > integrated exactly.
> > If it is possible for the form compiler to comply with this wish it may do so,
> > if not it will ignore the instruction.
> > On second thought, I think we do need 'quadrature', 'tensor' to be allowed in
> > the metadata, otherwise the user can't specify different representations on
> > different subdomains.
> > 
> 
> Perhaps this information should belong to the form rather than the integral?
> 
>      a_tensor = . . .
>      a_quad   = . . .
>      a = a_tensor + a_quad
> 
> Garth

I think it belongs in the integral. All terms need an integral
(measure) so it's practical to attach it to the integral.

-- 
Anders

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