dolfin team mailing list archive

[Johan Hake <johan.hake@xxxxxxxxx>]

On Monday April 4 2011 11:55:05 Garth N. Wells wrote:
> On 04/04/11 19:51, Johan Hake wrote:
> > Hello!
> > 
> > I would very much like to have something like:
> >   // Set the diagonal of a matrix
> >   GenericMatrix::set_diagonal(const GenericVector& vec);
> >   
> >   // Scale Matrix with a diagonal matrix (represented as a Vector)
> >   GenericMatrix::scale(const GenericVector& vec);
> >   (maybe use operator*=)
> > 
> > added to the GenericMatrix interface.
> > 
> > The corresponding backend specific methods would be:
> >   // PETSc
> >   MatDiagonalSet
> >   MatDiagonalScale
> >   
> >   // Epetra
> >   ReplaceDiagonalValues
> >   RightScale
> >   
> >   // MTL4/uBLAS find out later...
> > 
> > which should ensure the methods works in parallel too.
> > 
> > Any objections or advices in respect to implement these?
> 
> Fine with me, but could GenericMatrix::scale have a better name? It's
> not clear to me what it would do. Scale the diagonal, or scale the rows
> or the columns?

It basically doing:

  A*=D

where D is a diagonal matrix given by the a vector. And I guess this would 
then correspond to a column scale.

Johan
 
> Garth
> 
> > Best regards,
> > 
> > Johan
> > 
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