dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Mon, Apr 21, 2008 at 09:35:30PM +0200, Dag Lindbo wrote:
> >> Why do I care? I'm looking at the current state of the LinearPDE class.
> >> Here, the solution vector is a member function, and the solution
> >> Function is initialized with a reference to this vector. I.e. the
> >> LinearPDE (not the DiscreteFunction) owns the solution vector. This is
> >> of course a problem if the LinearPDE goes out of scope before the
> >> solution function (bug 24). It is also a bit counter-intuitive.
> >>
> >> If it was possible to do an initialization like above, then the solve()
> >> method would simply do
> >> u.init(mesh, form, 1);
> >> GenericVector& x = u.vector();
> >> <solve>
> >
> > There is a member local_vector in DiscreteFunction that could be used
> > for this. If this is nonzero, then the DiscreteFunction owns its data.
> >
> > See if you can figure out a good way for the DiscreteFunction to know
> > that it should take responsibility for the vector here.
> >
> 
> Right... I don't see how to do this without breaking the encapsulation of
> both Function and DiscreteFunction (making LinearPDE friend in both).
> Bundle attached.
> 
> Garth, does this look OK?
> 
> In essence, the member x is removed from the LinearPDE class. in
> LinearPDE::solve I do
> 
>   (...)
>   Vector b;
>   Vector* x = new Vector();
>   (... call solver etc)
> 
>   u.init(mesh, *x, a, 1);
>   DiscreteFunction& uu = dynamic_cast<DiscreteFunction&>(*u.f);
>   uu.local_vector = x;
> 
> /Dag

Looks like a good temporary solution to me.

I expect when we're done and happy with the linear algebra classes
(which should be soon), we will have a similar party with the function
classes... :-)

-- 
Anders