dolfin team mailing list archive

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

Anders, two comments:1.) You should use de Casteljau's algorithm for the
Bernstein polynomials.
2.) Using the recurrence relations in new version of FIAT will avoid
the singular mapping and should allow evaluation outside the reference
simplex.  But we need to make time to smooth this version out and
hook it up to ffc.

Rob

On Wed, Sep 23, 2009 at 6:00 PM, Anders Logg <logg@xxxxxxxxx> wrote:

> I just went through implementing Bernstein polynomials in Python
> because Marie and I needed them for our experiments with adaptivity
> and the FIAT basis functions could not be evaluated outside the
> triangles (the mapping being singular along y = 1).
>
> I've attached the code for the Bernstein polynomials. We will need to
> implement this in C++ at some point when things are working.
>
> --
> Anders
>
>
> On Wed, Sep 23, 2009 at 05:53:30PM -0500, Robert Kirby wrote:
> > It probably should be added in dolfin/ufc.  Sometimes we want to play
> around
> > with things that aren't supported by ffc yet.  Having a full-featured c++
> > library (and python bindings) would help.  An example would be Berstein
> > polynomials, which use a different evaluation method than in ffc/fiat.
>  Another
> > example is the transformation business I'm working that needs cell
> jacobians
> > and other geometric information.  I'd like to look at hand-done
> implementations
> > using the dolfin library (preferably PyDolfin) to make sure stuff works
> before
> > going through the labor of teaching ffc how to do it.
> >
> > Rob
> >
> > On Wed, Sep 23, 2009 at 5:45 PM, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
> >
> >
> >
> >     Robert Kirby wrote:
> >
> >         Is there a method for getting the Jacobian of a mapping to a
> reference
> >         cell in dolfin, or is this always generated by ffc?
> >
> >
> >
> >     It's generated by FFC. Could be a suggestion for an addition to UFC.
> >
> >     Garth
> >
> >
> >
> >
> >
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