dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Anders Logg wrote:
> On Fri, Apr 11, 2008 at 02:24:13PM +0200, Dag Lindbo wrote:
> > Anders Logg wrote:
> > > On Fri, Apr 11, 2008 at 01:34:24PM +0200, Martin Sandve Alnæs wrote:
> > > > 2008/4/11, Anders Logg <logg@xxxxxxxxx>:
> > > > > On Fri, Apr 11, 2008 at 12:23:15PM +0100, Garth N. Wells wrote:
> > > > >  >
> > > > >  >
> > > > >  > Anders Logg wrote:
> > > > >  > > Which one do we want to use for element access in vectors and
> > > > >  > > matrices. It looks like operator() is now implemented for uBlasVector,
> > > > >  > > but isn't operator[] more natural to use?
> > > > >  > >
> > > > >  >
> > > > >  > Much the same to me. We've used (.,.) for matrices, so it seems natural
> > > > >  > to use (.) for vectors.
> > > > >  >
> > > > >  > Garth
> > > > >
> > > > >
> > > > > We could use [] for matrices also I guess.
> > > > >
> > > > >  Then it will look the same as numpy.
> > > > It's useful to index vectors with [], since the code will be similar
> > > > for regular arrays.
> > > I forgot something important, namely that operator[] expects exactly
> > > one argument, so we can't do A[i, j] for matrices.
> > >
> > > Maybe then it's better to have () both for vectors and matrices?
> > Whatever you do with matrices, I don't have an opinion.
> >
> > However, I think operator[] should be present for vectors. One can argue 
> > that it does not _need_ to be there, but the fact is that it _is_ in the 
> > 0.7.2 interface (it worked until yesterday for uBlasVector, but it was 
> > maybe handled by uBlas itself?).
> >
> > /Dag
>
> Other opinions? Should we have both?
>
> Since we have A(i, j), it will be expected that x(i) works.
>
> But it will also be expected that x[i] works (since it works in numpy
> and it has worked before for uBlasVector).

Having both is fine with me. It can be a little confusing in the code 
because one might expect that a(2) and a[2] do different things.

Garth