ffc team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

Anders Logg wrote:
> On Mon, Apr 30, 2007 at 10:05:48AM +0200, Garth N. Wells wrote:
> > Anders Logg wrote:
> > > On Thu, Apr 26, 2007 at 05:02:18PM +0200, Garth N. Wells wrote:
> > > > When try to compile the code generated by FFC for the DOFLIN 
> > > > Cahn-Hilliard demo (src/demo/nls/cahn-hilliard/CahnHilliard2D.form) , I 
> > > > get the below errors related to undeclared variables.
> > > >
> > > > Garth
> > > >
> > > > CahnHilliard2D.h: In member function ‘virtual void 
> > > > UFC_CahnHilliard2DBilinearForm_cell_integral_0::tabulate_tensor(double*, 
> > > > const double* const*, const ufc::cell&) const’:
> > > > CahnHilliard2D.h:3136: error: ‘c3’ was not declared in this scope
> > > > CahnHilliard2D.h:3136: error: ‘c2’ was not declared in this scope
> > > > CahnHilliard2D.h:3136: error: ‘c1’ was not declared in this scope
> > > > CahnHilliard2D.h:4681: error: ‘c0’ was not declared in this scope
> > > > CahnHilliard2D.h: In member function ‘virtual void 
> > > > UFC_CahnHilliard2DLinearForm_cell_integral_0::tabulate_tensor(double*, 
> > > > const double* const*, const ufc::cell&) const’:
> > > > CahnHilliard2D.h:7572: error: ‘c3’ was not declared in this scope
> > > > CahnHilliard2D.h:7572: error: ‘c2’ was not declared in this scope
> > > > CahnHilliard2D.h:7572: error: ‘c1’ was not declared in this scope
> > > > CahnHilliard2D.h:9654: error: ‘c0’ was not declared in this scope
> > > I think the problem is that constants are no longer supported in
> > > UFC/FFC. They need to be mapped to DG(0) elements and this is something
> > > I haven't fixed yet.
> > Could you make it possible to invert DG(0) functions (e.g. 1/t)?
> >
> > Garth
>
> Yes (with some work), but is it necessary?
>
> You can define the corresponding function in DOLFIN as
>
>   Function cinv(mesh, 1.0/c);

Can be useful for terms like time t which can appear as t and 1/t, 
saving the introduction of an extra variable.

Garth


> /Anders
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