fiat team mailing list archive

["Robert Kirby" <robert.c.kirby@xxxxxxxxx>]

I will also point out that, even if FIAT had these element shapes, it would
be some work for FFC to adapt to use them.  We would be in the world of
non-affine transformations, which means that the tensor representation in
FFC would not work.  It can be generalized, but with some cost in run-time
operation count.
Rob

On Jan 24, 2008 9:15 AM, Martin Sandve Alnæs <martinal@xxxxxxxxx> wrote:

> 2008/1/24, Anders Logg <logg@xxxxxxxxx>:
> > On Thu, Jan 24, 2008 at 07:57:43AM -0600, Robert Kirby wrote:
> > > Well, FIAT really does simplices because they're hard.  Hexes and
> rectangles
> > > have tensor-product bases for H(div), H(curl), and H1, so you should
> really be
> > > doing spectral-type techniques.  See the thesis of Heintsch (sp?) at
> NYU for
> > > some interesting work on high order H(div) and H(curl) a few years
> ago.  Not
> > > sure if it got published, but it was very good
> > >
> > > I now have a user at Sandia who wants the other shapes, so I will be
> looking at
> > > doing this, either in Python or else with straight tensor-products in
> C++.  Of
> > > course, pyramids and prisms present wrinkles of being somewhere
> in-between.
> >
> > There has also been some interest in adding quads and hexes to the
> DOLFIN
> > mesh library (which should not be very hard) so this might also happen
> > (if someone has time to implement it).
> >
> > --
> > Anders
>
> As a sidenote, SyFi supports code generation for quads and hexes (at
> least Lagrange elements).
>
> --
> Martin
>
>
> > > On Jan 23, 2008 9:07 PM, Harish Narayanan <harish@xxxxxxxxxxx > wrote:
> > >
> > >     Greetings,
> > >
> > >     I understand from the documentation in FIAT that all its reference
> > >     elements treat spaces as simplicial complexes. Is there an obvious
> > >     difficulty in extending this to non-simplicial elements (assuming
> the
> > >     mesh is suitably generated elsewhere)?
> > >
> > >     I would be curious to read some literature on this topic if
> someone were
> > >     willing to point me to it.
> > >
> > >     Thanks,
> > >     Harish
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