ufl team mailing list archive

[Johan Hake <johan.hake@xxxxxxxxx>]

On Thursday May 12 2011 08:32:57 Anders Logg wrote:
> On Thu, May 12, 2011 at 05:16:30PM +0200, Martin Sandve Alnæs wrote:
> > On 12 May 2011 12:13, Anders Logg <logg@xxxxxxxxx> wrote:
> > > On Thu, May 12, 2011 at 10:52:50AM +0100, Garth N. Wells wrote:
> > >> Since there are no commit messages, can you tell us where the UFL/FFC
> > >> fixes to get DOLFIN working again are at?
> > > 
> > > How do you mean? I don't yet know which fixes should be made to get
> > > DOLFIN working again or I would have fixed it already.
> > > 
> > > I've fixed quite a few issues. FFC is green again and the test cases
> > > I've been using (JIT-compilation of Expressions and the DOLFIN
> > > function unit tests) run.
> > > 
> > > The changes I've made are mainly to analysis.py (FFC) and
> > > preprocess.py (UFL) + tons of other files.
> > > 
> > > The main outline of the change is:
> > > 
> > > 1. preprocess tries to figure out the common cell
> > > 
> > > 2. no elements are modified or mapped
> > 
> > Hmm...
> > 
> > Then the signature of the form will still be incomplete after
> > preprocessing. If there is no valid cell in the form, the form signature
> > does not identify whether it is in e.g. R^2 or R^3. Or am I missing
> > something?
> 
> That's true. I didn't think about that. Hmm...
> 
> But perhaps that's not really a problem after all? The form compiler
> should select the same elements the second time it sees a form with
> the same signature containing unknowns.
> 
> I can think of one case when this can go wrong which is the case when
> one integrates an expression over with unspecified domain in 2D, and
> then later wants to integrate the same expression in 3D, and the 2D
> version gets reused. We can get around this by including common_cell
> passed to the JIT compiler in the signature used for caching.
> 
> Are there other cases when this can go wrong?

Not sure this relates to the situation after the redesign, but I had a lot of 
triggered recompilations becuase sometimes the generated singatures included a 
'?' for the cell and sometimes it was given a cell, for the exact same form. 

Also I have included a cell argument to the Constant constructor in DOLFIN so 
a user can define the cell if he wants to. That fixed all my problems with 
form caching.

Johan

> --
> Anders
> 
> > > 3. FFC keeps track of suitable values for cells and degrees when they
> > > are missing (as part of element_data computed in analysis.py)
> > > 
> > > I'm about to leave my office and be offline for a few hours.
> > 
> > But the preprocess function does look nice now at least :)
> > 
> > Martin
> 
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