dolfin team mailing list archive

[Mehdi Nikbakht <m.nikbakht@xxxxxxxxxx>]

On Fri, 2011-01-28 at 12:55 +0100, Anders Logg wrote:
> On Fri, Jan 28, 2011 at 11:37:23AM +0000, Garth N. Wells wrote:
> >
> >
> > On 28/01/11 11:33, Mehdi Nikbakht wrote:
> > > On Fri, 2011-01-28 at 11:25 +0100, Andre Massing wrote:
> > >> Den 28.01.11 00.30, skrev Anders Logg:
> > >>> On Thu, Jan 27, 2011 at 11:10:08PM +0100, Anders Logg wrote:
> > >>>> I would like to add factory functions in UFC, in particular
> > >>>>
> > >>>>    finite_element* finite_element::create() const;
> > >>>>    dof_map* dof_map::create() const;
> > >>>>
> > >>>> Are there any objections to this? It would be easy to add and easy to
> > >>>> implement in FFC.
> > >>>>
> > >>>> I need it to implement refinement of FunctionSpaces in DOLFIN where
> > >>>> fresh copies of ufc::finite_element and ufc::dof_map are needed given
> > >>>> a ufc::finite_element or ufc::dof_map.
> > >>>>
> > >>>> An alternative is to hack create_sub_foo so that it returns a copy of
> > >>>> the element/dofmap itself if the component argument 'i' is>= the
> > >>>> number of sub elements/dofmaps.
> > >>>
> > >>> I suggest we add this to UFC 1.6 and make a release next week together
> > >>> with DOLFIN 0.9.10, FFC 0.9.5 + other packages that need release. The
> > >>> sooner the better: there will be time to make bug fix releases and
> > >>> things will be tested before 1.0 in March.
> > >>>
> > >>> If there are any other things we want to add to UFC, now's a good
> > >>> time.
> > >>
> > >> What about the tabulate_tensor function taking arguments for runtime
> > >> quadrature rules, as we discussed a while ago? ATM I hacked UFC and my
> > >> generated form files having an additional function
> > >>
> > >> virtual void tabulate_tensor(double* A,
> > >>                               const double * const * w,
> > >>                               const ufc::cell& c,
> > >> 			     dolfin::uint num_quad_points,
> > >> 			     const double * const * coordinates,
> > >> 			     const double * weights) const
> > >>
> > >> Such an interface would add a flexible layer for those who wants to have
> > >> some type of runtime quadrature.
> > >>
> > >> General opinons about that?
> > >
> > > Although this makes life easier for the case that we have to compute
> > > quadrature rule in the run-time, but the current interface can also
> > > handle this problem.  You can derive a class form ufc::foo_integrals and
> > > pass object containing new gauss quadrature rule to its constructor as
> > > we do for partition of unity method.
> 
> How is that possible? I assume you make a subclass and implement the
> tabulate_tensor functions yourself using the points given in the
> constructor. That's fine, but the point here would be that FFC
> generates the code for us and the generated code would use the
> quadrature points.

Yes, we generate required code for tabulate_tensor using ffcpum. The
most important point is runtime evaluation of basis function and their
derivatives using object of ufc::finite_element at the given quadrature
points. The approach used for run-time computation of quadrature points
is a secondary issue. These quadrature points can be given to the
constructor of foo_integrals (as we it do now) or can be passed through
tabulate_tensor(as the proposed interface can do). 

Mehdi

> > I think that the proposed interface change would make the above process
> > simpler.
> 
> If we agree it's a good interface, we could put it in now for 1.6. It
> will make it easier once we implement since no change in UFC will be
> needed at that point.
> 
> --
> Anders
> 
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