On 20111112@18:25, Jordi GutiƩrrez Hermoso wrote:
> On 12 November 2011 18:18, Carlo de Falco <carlo.defa...@gmail.com> wrote:
> > On 12 Nov 2011, at 16:04, c. wrote:
> >> On 12 Nov 2011, at 12:17, Alexander Barth wrote:
> > ....
> > It looks like it's working:
> >
> >>> n = 1000;
> >>> A = 15 * eye (n) + sprandn (n, n, .2);
> >>> b = ones (n, 1);
> >>> P = diag (diag (A));
> >>> tic, [x, flag] = gmres (A, b, [], 1e-7, n, P); toc
> > Elapsed time is 1.73299 seconds.
> >>> As = sparsersb (A);
> >>> tic, [x, flag] = gmres (As, b, [], 1e-7, n, P); toc
> > Elapsed time is 1.40307 seconds.
> >
> > the speed-up is nothing to write home about though but, still,
> > it's a really nice package and already usable,
> > so Michele keep up with the good work :)
> 
> That's a tiny sparse matrix. I'm curious about how the algorithm
> scales. Can you try a couple of orders of magnitude larger?
> 
> Also, what version of Octave is that? Are you working on dev or stable?
Hahahaha :)
Yes Jordi is right: you should try much large matrices, possibly with
tens of elements per row.
See the articles on http://claudius.ce.uniroma2.it/~martone/ as soon as
the webserver is back to life.
I have yet to document much of librsb: there are different tuning
parameters involved in librsb's operation.

But generally, with smaller matrices (e.g.: as a rule of thumb, ones
fitting in the L2 cache) it's not even said that operation was really
parallel (it depends on the matrix partitioning; maybe this could be
interesting to "visualize" in some way...; if the "recursive
partitioning" was not applied at all, operation was serial).

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