dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

ok, so I know what the problem is.

If you write

    Stokes12::LinearForm(f) lform0(f);
    Stokes23::LinearForm(f) lform1(f);

then f first gets associated with Stokes12 and then you reassociate it
with Stokes23, so at the point where you then want to assemble first
Stokes12, the Function f is associated with the FiniteElement for
Stokes23, so it tries to interpolate its values at more points than it
should (the nodal points for Stokes23 rather than Stokes12).

I think the best way to solve this is a redesign of the Function
class, so that user-defined Functions are not associated with a
particular FiniteElement. I'll send a suggestion in a separate post.

/Anders

On Wed, Nov 09, 2005 at 09:23:34AM -0600, Anders Logg wrote:
> ok, I suspected as much.
> 
> I'll see if I can reproduce it. It should be an easy fix.
> 
> /Anders
> 
> On Wed, Nov 09, 2005 at 09:17:27AM -0600, Andy Ray Terrel wrote:
> 
> > Okay so I am getting the error when I don't use the arrays as Anders 
> > suggested, but the error goes away when I define two functions f0, and 
> > f1.  And build the forms off of them.
> > 
> > Andy
> > 
> > 
> > 
> > Anders Logg wrote:
> > 
> > >Do you get the same error if you don't use arrays? Say that you do
> > >
> > >#include "Stokes12.h";
> > >#include "Stokes23.h";
> > >
> > >MyFunction f;
> > >MyBC bc;
> > >
> > >Stokes12::BilinearForm bform0;
> > >Stokes23::BilinearForm bform1;
> > >Stokes12::LinearForm(f) lform0(f);
> > >Stokes23::LinearForm(f) lform1(f);
> > >
> > >UnitSquare mesh(8,8);
> > >Matrix A;
> > >Vector x, b;
> > >
> > >FEM::assemble(bform0, lform1, A, b, mesh, bc);
> > >FEM::assemble(bform1, lform1, A, b, mesh, bc);
> > >
> > >The only thing I can think of is that f is used in both forms. That
> > >should be ok, but it could be the cause.
> > >
> > >/Anders
> > >
> > >On Wed, Nov 09, 2005 at 08:45:52AM -0600, Andy Ray Terrel wrote:
> > > 
> > >
> > >>Recently I have had some trouble putting LinearForm pointers into an 
> > >>array and trying to work on them.  Basically if I have more than one in 
> > >>the array I either get a segfault or numbers that don't match up to when 
> > >>I am doing things without the array.  The code looks something like this:
> > >>---------------------------------------------------------------------------------------------------
> > >>include "Stokes12.h";
> > >>include "Stokes23.h";
> > >>
> > >>MyFunction f;
> > >>MyBC bc;
> > >>
> > >>BilinearForm* bforms[2]={new Stokes12::BilinearForm(), new 
> > >>Stokes23::BilinearForm()};
> > >>LinearForm* lforms[2]={new Stokes12::LinearForm(f), new 
> > >>Stokes23::LinearForm(f)};
> > >>for(int i=0; i<2; i++){
> > >>  ...
> > >>  UnitSquare mesh(8,8);
> > >>  Matrix A;
> > >>  Vector x, b;
> > >>  FEM::assemble(*(bforms[i]), *(lforms[i]), A, b, mesh, bc);
> > >>  ...
> > >>}
> > >>------------------------------------------------------------------------------------------------
> > >>
> > >>So I have gotten around the problem by using python to just write the 
> > >>different files and running them, but I thought someone might want to 
> > >>know about the problem I was having.
> > >>
> > >>
> > >>   
> > >>
> > >
> > > 
> > >
> > 
> 

-- 
Anders Logg
Research Assistant Professor
Toyota Technological Institute at Chicago
http://www.tti-c.org/logg/