dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Wed, Oct 07, 2009 at 10:59:28PM +0200, Johan Hake wrote:
> On Wednesday 07 October 2009 22:33:06 Anders Logg wrote:
> > On Wed, Oct 07, 2009 at 10:30:42PM +0200, Johan Hake wrote:
> > > On Wednesday 07 October 2009 21:58:36 Garth N. Wells wrote:
> > > > The Python mixed-poisson demo is failing in parallel because the
> > > > extraction of sub-functions via split() is making a deep copy, even
> > > > though it should be a 'shallow' copy. Any ideas on how to fix it?
> > >
> > > Yes I see now whats wrong... I thought that the assignment operator
> > > somewhat kept the shallow copy.
> > >
> > > I think we need to add the hack we had previously in DiscreteFunction to
> > > make it work again. Should we add this in Function directly or should I
> > > try to subclass Function and implement that particular constructor? I
> > > would prefer the first.
> >
> > What is the hack? Yes, it would be good to avoid creating a special
> > subclass.
>
> It is this constructor we need.
>
>    /// Sub-function constructor (shallow copy of the vector)
>    DiscreteFunction(Function& v, uint i)
>    {
>      // Check that vector exists
>      if (!v.has_vector())
>        error("Unable to extract sub function, missing coefficients (user-
> defined function).");
>
>      // Get sub-function (Function will store pointer to sub-Function)
>      Function& sub_function = v[i];
>
>      // Copy function space pointer
>      this->_function_space = sub_function._function_space;
>
>      // Copy vector pointer
>      this->_vector = sub_function._vector;
>    }

Looks ok to me (except for the has_vector thing which has been removed).

--
Anders

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