On 04/04/11 20:20, Johan Hake wrote: > On Monday April 4 2011 12:13:22 Anders Logg wrote: >> On Mon, Apr 04, 2011 at 08:10:22PM +0100, Garth N. Wells wrote: >>> On 04/04/11 20:00, Johan Hake wrote: >>>> 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. >>> >>> OK. It might get complicated, but we could have a >>> >>> (Generic)DiagonalMatrix >>> >>> class? > > Hmm, letting it inherit GenericVector? This path would open up a box of > things > we have to consider... Maye fire up a Blueprint and add other thoughts on > that. > >>> Otherwise, GenericMatrix::right_scale is probably an OK name. > > Ok. > >> I think scale_columns is more informative, if that is what it actually >> does. >> >> (Is it implied by A *= D that it corresponds to A = A * D or can it be >> A = D * A?) > > Yes, no. > > The first one is called RightScale and the second (I guess) is called > LeftScale in Epetra. In PETSc it is put into the same function. > > I could add right_scale and left_scale, or row_scale and column_scale. No big > deal from me. >
'left' and 'right' is consistent with preconditioner terminology, and with the Trilinos and PETSc naming. Garth > Johan > >> -- >> Anders >> >>> Garth >>> >>>> Johan >>>> >>>>> Garth >>>>> >>>>>> Best regards, >>>>>> >>>>>> Johan >>>>>> >>>>>> _______________________________________________ >>>>>> Mailing list: https://launchpad.net/~dolfin >>>>>> Post to : dolfin@lists.launchpad.net >>>>>> Unsubscribe : https://launchpad.net/~dolfin >>>>>> More help : https://help.launchpad.net/ListHelp >>>>> >>>>> _______________________________________________ >>>>> Mailing list: https://launchpad.net/~dolfin >>>>> Post to : dolfin@lists.launchpad.net >>>>> Unsubscribe : https://launchpad.net/~dolfin >>>>> More help : https://help.launchpad.net/ListHelp >>> >>> _______________________________________________ >>> Mailing list: https://launchpad.net/~dolfin >>> Post to : dolfin@lists.launchpad.net >>> Unsubscribe : https://launchpad.net/~dolfin >>> More help : https://help.launchpad.net/ListHelp _______________________________________________ Mailing list: https://launchpad.net/~dolfin Post to : dolfin@lists.launchpad.net Unsubscribe : https://launchpad.net/~dolfin More help : https://help.launchpad.net/ListHelp
