dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Feb 17, 2009 at 03:28:08PM +0000, Garth N. Wells wrote:
> 
> 
> A Navaei wrote:
> > The following minimal test for Function in c++ reveals some bugs. I
> > guess this example can help me with dealing with the current issues of
> > ImageFunction.
> > 
> > (1) interpolate.py does not work when a Function is created in c++ and
> > wrapped (see comment [2]). It seems that the bug is originated from
> > the copy constructor (see comment [3])
> > 
> > (2) In order to perform the interpolation, why is it necessary to
> > create another Function and then copy it?
> > 
> > (3) Signature checkes seem not working properly (see comment [1]). The
> > signature-based assignments are error-prone anyway, why the
> > object-oriented approach is not used?
> > 
> 
> Signatures are used to permit reading/writing Functions to a file. They 
> are indeed error prone, so I believe that we reached a consensus a short 
> while ago that we would remove pre-compiled elements.
> 
> Garth

Instead of signatures, I'd recommend that you define a simple form
file for each of the different types of FunctionSpace you need, for
example:

  element = FiniteElement("CG", "triangle", 1)

  v = TestFunction(element)
  u = TrialFunction(element)
  a = v*u*dx

If you put this in a file named My.form and compile it with FFC using
-l dolfin, you will get a class named MyFunctionSpace that you can
then instantiate using just a mesh:

  MyFunctionSpace V(mesh);

Create one form file for each of the different types of FunctionSpace
that you need, name the files to something suitable and use the
generated code. That way you won't need to worry about signatures,
dofmaps and finite elements.

-- 
Anders

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