dolfin team mailing list archive

[Johan Hake <johan.hake@xxxxxxxxx>]

On Wednesday April 27 2011 12:03:56 Martin Sandve Alnæs wrote:
> On 27 April 2011 19:07, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
> > I'm starting here a new thread on how to deal with the recent change in
> > UFL that has broken a good number of DOLFIN demos. The previous thread
> > meandered and got side-tracked.
> > 
> > The framework in we need to operate is:
> > 
> > A. UFL will not allow forms to be modified post-construction.
> > 
> > B. It should be relatively easy to replace ufl.Coefficients in a form
> > and return a new form.
> > 
> > C. The issue with replacing ufl.Coefficients is that we lose DOLFIN data
> > (like the eval() functions) associated with the removed coefficients.
> > 
> > 
> > I'll kick off with the obvious solution:
> > 
> > 1. Require that all DOLFIN Expressions are associated with a
> > ufl.FiniteElement.
> > 
> > Other solutions?
> > 
> > Garth
> 
> 2.  At the stage when ffc calls ufl.preprocess, or even in ufl.preprocess,
> let the preprocessed form contain ufl Coefficients with new elements in
> place of the dolfin.Expressions. This is similar to the replacements done
> for renumbering of Coefficients, and could either be done simultaneously or
> as an additional step. The original Form and Expression objects will be
> untouched, and the preprocessed form will be fine.

+

However, setting cell and degree is done during analysis and relies on 
form_data. The form is also preprocessed when the form_data is extracted. This 
means that for the preprocessed form to get correct signature, cell and 
degrees being set, we need to break up the logic.

  1) extract form_data
  2) set degree and cell
  3) genererate preprocessed form

Johan

  

Johan

> Martin