dolfin team mailing list archive

["Matthew Knepley" <knepley@xxxxxxxxx>]

On Mon, May 19, 2008 at 8:20 AM, Anders Logg <logg@xxxxxxxxx> wrote:
> It looks to me like the storage needed is indeed n^2*num_cells. I'm
> not fluent in Fortran, but that's how I interpret this line:
>
>  atw(idxatw(el,li,lj)) = atw(idxatw(el,li,lj)) + Atmp(li,lj)
>
> This looks expensive (in terms of memory), but maybe not that
> expensive?

I think I should make the aggregation point again. The above line executes
a function call for insertion of every value. This is a lot of
overhead, not only
for the call, but setting up loop bounds etc. That is why MatSetValues takes
logical blocks, exactly what you get from FEM, I believe this could be the
difference between our timing results.

   Matt

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which
their experiments lead.
-- Norbert Wiener