Subject: [FFC-dev] Transition to UFL-based forms

From: "Garth N. Wells" <[email-masked]>
Date: Fri, 17 Apr 2009 09:32:26 +0800

Should we start moving to UFL-based forms for the DOLFIN demos? Is the 
only serious outstanding issue on the FFC side the correct determination 
of the quadrature order?

Garth

---

From: Johan Hake <[email-masked]>
Date: Fri, 17 Apr 2009 08:59:43 +0200

> only serious outstanding issue on the FFC side the correct determination

Not sure how this could be best done in PyDOLFIN. 

We could add

  from dolfin.ufl import *

after each 

  from dolfin import *

in the demos. When this is done and it all just works(TM) we can move the 
files in the site-packages/dolfin/ufl directory down to site-packages/dolfin, 
and remove

  from dolfin.ufl import *

from the demos?

Johan

> Garth
> _______________________________________________
> DOLFIN-dev mailing list
> [email-masked]
> http://www.fenics.org/mailman/listinfo/dolfin-dev

---

From: Anders Logg <[email-masked]>
Date: Fri, 17 Apr 2009 09:04:14 +0200

> files in the site-packages/dolfin/ufl directory down to site-packages/dolfin, 

I suggest we just move everything to UFL at once and then solve any
problems that we encounter.

I'm intending to remove the .form support from FFC quite soon (maybe
today).

It's easier to fix things so that they work with UFL than to have two
conflicting form languages work at the same time.

-- 
Anders

---

From: "Garth N. Wells" <[email-masked]>
Date: Fri, 17 Apr 2009 15:07:17 +0800

> conflicting form languages work at the same time.

The quadrature issue is serious, so I think that it should be tackled 
before the transition, or at least a short-term plan for how to solve it 
should be in place.

Garth

> 
> 
> ------------------------------------------------------------------------
> 
> FFC-dev mailing list
> [email-masked]
> http://www.fenics.org/mailman/listinfo/ffc-dev

---

From: Johan Hake <[email-masked]>
Date: Fri, 17 Apr 2009 09:15:59 +0200

On Friday 17 April 2009 09:04:14 Anders Logg wrote:
> > > only serious outstanding issue on the FFC side the correct
> > > determination of the quadrature order?
> >
> > files in the site-packages/dolfin/ufl directory down to
> > site-packages/dolfin, and remove
> >
> >   from dolfin.ufl import *
> >
> > from the demos?
> >
> > Johan
>

Ok.

I wont be around untill the end of next week.

Johan

---

From: Anders Logg <[email-masked]>
Date: Fri, 17 Apr 2009 09:50:16 +0200

> before the transition, or at least a short-term plan for how to solve it 

Is it so serious? It's a small thing compared to what will happen when
the .form support is removed from FFC (as in everything will be broken
until fixed).

What is the problem with the quadrature order. Is it
extract_quadrature_order and estimate_quadrature_order not working
properly in UFL? What is the difference between the two?

-- 
Anders

---

From: "Garth N. Wells" <[email-masked]>
Date: Fri, 17 Apr 2009 15:57:09 +0800

> the .form support is removed from FFC (as in everything will be broken

Results computed with the new and old formats will not, in general, be 
the same, so I considered it to be serious.

> properly in UFL? What is the difference between the two?

My most recent understanding is that these are not working as they should.

Garth

---

From: Anders Logg <[email-masked]>
Date: Fri, 17 Apr 2009 11:03:25 +0200

> the same, so I considered it to be serious.

Yes, they won't be the same but I thought they would still be correct
(as in possibly using a better quadrature rule than needed).

Kristian?

-- 
Anders

---

From: "Garth N. Wells" <[email-masked]>
Date: Fri, 17 Apr 2009 20:29:37 +0800

> (as in possibly using a better quadrature rule than needed).

No, it uses a lower degree of quadrature. For example, for the Poisson 
demo using the new UFL format only one quadrature point is used for the 
source term, whereas enough points for a quadratic polynomial are required.

Not quite sure what 'not the same but still correct' means ;).

Garth

---

From: Martin Sandve Alnæs <[email-masked]>
Date: Fri, 17 Apr 2009 14:40:51 +0200

Look at the latest commit.

Martin

---

From: Kristian Oelgaard <[email-masked]>
Date: Fri, 17 Apr 2009 18:12:39 +0200

> >>>>> conflicting form languages work at the same time.

I agree on this.

> Not quite sure what 'not the same but still correct' means ;).

As far as I can tell the current implementation in UFL will result in a
sufficient degree of quadrature being used.

Kristian

---

From: "Garth N. Wells" <[email-masked]>
Date: Sat, 18 Apr 2009 07:51:22 +0800

> sufficient degree of quadrature being used.

I've tested it, and not in all cases are enough quadrature points used 
for exact integration.

Martin made some changes to UFL yesterday to help in getting the 
quadrature order right.

Garth