dolfin team mailing list archive

[Johan Jansson <johanjan@xxxxxxxxxxxxxxxx>]

On Thu, Jul 13, 2006 at 04:56:29PM +0200, Anders Logg wrote:
> On Thu, Jul 13, 2006 at 04:54:43PM +0200, Johan Jansson wrote:
> > On Thu, Jul 13, 2006 at 01:02:29PM +0200, Garth N. Wells wrote:
> > 
> > ...
> > 
> > > Johan, any news on wrapping the uBlas functions? It would be good to
> > > sort this out before proceeding too far with the linear algebra clean
> > > up. We could change uBlasMatrix to look like
> > > 
> > >   template<class Mat>
> > >   class uBlasMatrix : public Variable, public GenericMatrix, 
> > >                       public uBlasKrylovMatrix
> > >   {
> > >     public:
> > >       .
> > >       .
> > > 
> > >     private:
> > >       Mat* mat;
> > >   }
> > > 
> > > Would this work with Swig?
> > 

...

> Which part of the uBlas interface for a uBlasSparseMatrix will we
> export? If we are not exporting anything more than what is in the
> interface of uBlasSparseMatrix (including GenericMatrix), then we
> don't need to make uBlasSparseMatrix a subclass of the uBlasMatrix
> template anyway and could have a uBlasMatrix as a private member as in
> the PETSc wrappers.
...
> As far as I can tell, the advantage of the templating to reduce code
> size would still remain even if we make uBlasMatrix<...> a private
> member. Would then the only argument to have the uBlas wrappers as
> subclasses of a template the convenience when working directly through
> the original uBlas interface in C++?
> 
> /Anders

I think (but I could have misunderstood) the advantage is that
templates allow us to define a single uBlasMatrix (which could be
defined as above, i.e. the same design as for PETSc) for sparse and
dense matrices. Then we can just declare:

typedef uBlasMatrix<ublas_sparse_matrix> uBlasSparseMatrix;

typedef uBlasMatrix<ublas_dense_matrix> uBlasDenseMatrix;

If we're not allowed to define template classes, then we need to
duplicate the code in uBlasSparseMatrix and uBlasDenseMatrix. This is
a consequence of uBlas using templates instead of inheritance to
define its matrix types.

  Johan