dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Jun 30, 2008 at 12:50:39PM +0200, Martin Sandve Alnæs wrote:
> 2008/6/28 Anders Logg <logg@xxxxxxxxx>:
> > On Sat, Jun 28, 2008 at 08:55:44PM +0200, Johan Hake wrote:
> >> Hello!
> >>
> >> I tried to compile an advection diffusion form using Streamline Upwind Petrow
> >> Galerkin stabilazing method, similar to the one introduced in DOLFIN 0.6.4.
> >> Using 3 dimensional and first degree Lagrange elements, FFC/g++ chokes when
> >> the produced code is compiling. It wont finish compile... Is this a known
> >> problem and a limitation of FFC/g++?
> >
> > Try compiling with the -r quadrature option. I guess this is not
> > supported in the JIT compiler yet, but could easily be added. There
> > should be an option
> >
> >  dolfin_set("form representation", "quadrature");
> >
> > in the same way as there is an option "optimize". See if you can
> > figure it out and send a patch, or else file a bug report.
> >
> > Options are added in DefaultParameters.h in DOLFIN and the JIT
> > compiler is in jit.py in FFC.
> >
> > Possible options for "form representation" are "tensor", "quadrature"
> > and (unsupported at the moment) "symbolic" (for SyFi).
> >
> > The quadrature representation generates much less code than the tensor
> > representation.
> 
> SFC also does quadrature (in fact most users (me) mainly use that),
> and there are many possible compilation options. I don't think it's a good
> idea to mix form compiler details into dolfin. We should talk about this
> to find a solution that doesn't discriminate form compilers :-)

I think we need have to. It is DOLFIN that sends the form to the form
compiler so DOLFIN needs to make a choice which form compiler to use.

But I agree we should not discriminate form compilers. Any form
compiler that handles UFL/UFC should be possible to use.

-- 
Anders


> The same goes for mixing ffc_Function into dolfin.Function, which means
> I have to write pydolfin code differently from the demos in many cases.
> It's also not possible to inherit ffc_Function in a compiled C++
> function anyway,
> which is vital for efficient assembly.
>

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