On Mon, May 19, 2008 at 08:30:20AM -0500, Matthew Knepley wrote: > On Mon, May 19, 2008 at 8:20 AM, Anders Logg <[EMAIL PROTECTED]> 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,
No, I think the above code would be very much faster than PETSc, but use more memory. The way I interpret it, atw is an array and idxatw is a *dense* rank 3 tensor so there's no searching, only lookup. > 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. No, the above code is not what we use in DOLFIN. We use MatSetValues with blocks. The above code is femLego Fortran code. -- Anders _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
