dolfin team mailing list archive

[Johan Hake <johan.hake@xxxxxxxxx>]

On Monday April 4 2011 11:58:30 Anders Logg wrote:
> On Mon, Apr 04, 2011 at 11:51:12AM -0700, 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?
> 
> Not from me. There was recently a question about this on the mailing
> list (on creating an identity matrix).

That should be easy to do with the set_diagonal method on a zeroed Matrix.

> A related question is whether its possible to speedup ident_zeros.
> It's quite slow at the moment. Is there a version of MatDiagonalSet
> which takes an index set?

I have just briefly looked at the PETSc Mat man page but could realy not find 
something that would work. I am pretty sure the set method set the whole 
diagonal using a dense vector.

Johan

> --
> Anders
> 
> > Best regards,
> > 
> > Johan
> > 
> > _______________________________________________
> > Mailing list: https://launchpad.net/~dolfin
> > Post to     : dolfin@xxxxxxxxxxxxxxxxxxx
> > Unsubscribe : https://launchpad.net/~dolfin
> > More help   : https://help.launchpad.net/ListHelp
> 
> _______________________________________________
> Mailing list: https://launchpad.net/~dolfin
> Post to     : dolfin@xxxxxxxxxxxxxxxxxxx
> Unsubscribe : https://launchpad.net/~dolfin
> More help   : https://help.launchpad.net/ListHelp