ffc team mailing list archive

[Kristian Oelgaard <k.b.oelgaard@xxxxxxxxxx>]

Quoting "Garth N. Wells" <gnw20@xxxxxxxxx>:

>
>
> Kristian Oelgaard wrote:
> > Quoting "Garth N. Wells" <gnw20@xxxxxxxxx>:
> >
> >>
> >> Anders Logg wrote:
> >>> FFC is now fully functional w.r.t. compilation of UFL forms, at least
> >>> judging by the demos in FFC which now all produce correct results.
> >>>
> >>> The Poisson demo in DOLFIN has also been moved to UFL.
> >>>
> >>> I therefore suggest we make new releases of FFC, UFL and DOLFIN:
> >>>
> >>>   DOLFIN 0.9.2
> >>>   FFC 0.6.2
> >>>   UFL 0.1.0 ?
> >>>   SyFi/SFC?
> >>>
> >>> This batch of releases will support both the old .form format and the
> >>> new .ufl format. After the release, we can get started on cleaning up
> >>> and removing the .form format.
> >>>
> >>> In it's simplest form, the UFL form language looks very much like the
> >>> FFC form language. Here's a comparison for the Poisson demo:
> >>>
> >>> FFC
> >>> ---
> >>>
> >>>   element = FiniteElement("Lagrange", "triangle", 1)
> >>>
> >>>   v = TestFunction(element)
> >>>   u = TrialFunction(element)
> >>>   f = Function(element)
> >>>
> >>>   a = dot(grad(v), grad(u))*dx
> >>>   L = v*f*dx
> >>>
> >>> UFL
> >>> ---
> >>>
> >>>   element = FiniteElement("Lagrange", triangle, 1)
> >>>
> >>>   v = TestFunction(element)
> >>>   u = TrialFunction(element)
> >>>   f = Function(element)
> >>>
> >>>   a = inner(grad(v), grad(u))*dx # dot also works
> >>>   L = v*f*dx
> >>>
> >>> However, UFL does much more, like treatment of tensor expressions,
> >>> nonlinear operators like sin, cos, exp, sqrt, differentiation of forms
> >>> w.r.t. variables etc. For more information, look at Martin's summary:
> >>>
> >>>   http://www.fenics.org/wiki/UFL
> >>>
> >>> UFL includes a script form2ufl that can be used to convert from the
> >>> old FFC form language to the new UFL form language. The script is not
> >>> foolproof but it may help in converting to the new format.
> >>>
> >>> So, let's make a new release now (after getting the buildbot green
> >>> again for DOLFIN) and then make the full transition after the release.
> >>>
> >>> It's also time to promote UFL from a development project (/dev) to a
> >>> proper project (/hg) since now FFC, SFC and DOLFIN will depend on it.
> >>> Any objections?
> >>>
> >> It would be worth checking with Kristian how far away the quadrature
> >> optimisations are for FFC + UFL. If it's only a few days, it would be
> >> good to wait on the FFC release since the new quadrature code is quite a
> >> bit slower than the old code (around a factor of 5 in some of my tests).
> >
> > It's already there, just uncomment the optimise_options lines at the top of
> the
> > uflquadraturegenerator.py file.
>
> How about turning this on when the FFC optimisation flag is used (-O,
> --optimize)?

This was on my TODO list and now it has been done.

Kristian

> Garth
>
> > However, there might still be bugs in the generated code and it compiles
> slower
> > (I've seen a factor of around 6-7 in some cases)
> >
> > Some benchmark tests:
> >
> > PressureEquation       FFC comp.    num. ops  assemble 2.5e6 times
> > Old FFC (*.form),+opt: 45.0s         26679          28.2s
> > New FFC (*.ufl), -opt:  0.9s        166086         110.0s
> > New FFC (*.ufl), +opt:  3.4s         15771          21.8s
> >
> > DGElastoDynamics  FFC comp. | ops. a, dx | ops. a, dS | ops. L, dx | ops.
> L, dS
> > (*.form), +opt:     16m20s        791        2098         1571         4305
> > (*.ufl),  -opt:         7s      25776       93600        10008        23280
> > (*.ufl),  -opt:        45s       1217        2529         1375         2923
> >
> > For the elasto-dynmics case, running 10 time steps on a 9000 element mesh
> takes
> > roughly 14.5s for both of the two optimised versions. The new FFC without
> > optimisation runs 1 second slower (15.6s).
> >
> > Kristian
> >
> >> Garth
> >>
> >>
> >>>
> >>> ------------------------------------------------------------------------
> >>>
> >>> _______________________________________________
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> >>> UFL-dev@xxxxxxxxxx
> >>> http://fenics.org/mailman/listinfo/ufl-dev
> >>
> >> _______________________________________________
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> >> UFL-dev@xxxxxxxxxx
> >> http://fenics.org/mailman/listinfo/ufl-dev
> >>
> >
> >
>