ffc team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Mar 22, 2010 at 01:43:41PM +0100, Marie Rognes wrote:
> Marie Rognes wrote:
> >Anders Logg wrote:
> >>On Mon, Mar 22, 2010 at 11:41:42AM +0100, Marie Rognes wrote:
> >>>Anders Logg wrote:
> >>>>On Mon, Mar 22, 2010 at 06:20:00PM +0800, Garth N. Wells wrote:
> >>>>>On 22/03/10 16:42, Kristian Oelgaard wrote:
> >>>>>>On 21 March 2010 21:32, Anders Logg <logg@xxxxxxxxx> wrote:
> >>>>>>>After Marie's latest addition of enriched spaces (and
> >>>>>>>some discussion
> >>>>>>>with Doug Arnold), it seems clear that our current
> >>>>>>>notation V + W for
> >>>>>>>mixed spaces is not optimal.
> >>>>>>>
> >>>>>>>Even though one may think of the operation of creating a "mixed
> >>>>>>>function space" as a direct sum,
> >>>>>>>
> >>>>>>>X = {(v, 0) : v in V} \oplus {(0, w) : w in W},
> >>>>>>>
> >>>>>>>it is more natural (and common) to think of it as a
> >>>>>>>Cartesian product,
> >>>>>>>
> >>>>>>>X = V \times W = {(v, w) : v in V, w in W}
> >>>>>>>
> >>>>>>>It would therefore be more natural to use '*' instead of '+' as the
> >>>>>>>operation for creating mixed elements/function spaces.
> >>>>>>>
> >>>>>>>That would free up '+' to be used for enriched spaces (which have
> >>>>>>>recently been added),
> >>>>>>>
> >>>>>>>X = {v + w : v in V, w in W}
> >>>>>>>
> >>>>>>>The typical example would be to take V piecewise
> >>>>>>>linears and W scaled
> >>>>>>>P3 bubbles.
> >>>>>>>
> >>>>>>>In summary, the suggestion is to use the following notation:
> >>>>>>>
> >>>>>>>+ <-->  +
> >>>>>>>* <-->  \times
> >>>>>>>
> >>>>>>>It's obvious this is better than what we have now which is
> >>>>>>>
> >>>>>>>+ <--> \oplus
> >>>>>>>? <--> +
> >>>>>>>
> >>>>>>>Thoughts?
> >>>>>>Agree.
> >>>>>>
> >>>>>Me too.
> >>>>>
> >>>>>Garth
> >>>>ok. Let's change then.
> >>>>
> >>>>It will require changes in both UFL and FFC. Anyone up for it?
> >>>I can fix ffc.
> >>
> >>I was hoping for that. :-)
> >>
> >>>(Have no permission for ufl)
> >>
> >>You do now. ;-)
> >>
> >
> >Aka, I'll fix that too.
> >
>
> Fixed:
>
> (a) ElementUnion is now called EnrichedElement.
>
> (b) (Old) V + Q --> (New) V * Q
>
> (c) V + Q = EnrichedElement(V, Q)
>
>
> Now, PYDOLFIN needs updating...

Done.

--
Anders

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