Anders, Martin: Dirichlet Boundary conditions?
On Sun, Apr 5, 2009 at 5:58 AM, Martin Sandve Alnæs <[email protected]>wrote: > UFL defines action so you don't have to rewrite/duplicate your form: > > a = u*v*dx > b = action(a, f) # == f*v*dx > > Martin > > > > On Sun, Apr 5, 2009 at 10:34 AM, Anders Logg <[email protected]> wrote: > > On Sat, Apr 04, 2009 at 08:30:39PM -0500, Robert Kirby wrote: > >> Thanks, I'll take a look next week. > >> > >> One thought that would take a little work but might be worth exploring > from the > >> ffc end would be > >> to define matrix actions in the form compiler that map to KrylovMatrix > rather > >> than Matrix. > >> For example, one can take the Poisson code, replacing the TrialFunction > with > >> Function, so that > >> > >> v = TestFunction(V) > >> u = Function(V) > >> a = dot(grad(v), grad(u))*dx > >> > >> and then generate code for a KrylovMatrix subclass. Anders and I > experimented > >> with the effects of ferari-optimization and found that they were most > profound > >> in this context. It also removes the assembly bottleneck since you > don't have > >> to beat on a sparse matrix. On the other hand, you don't have the > matrix to > >> feed to algebraic preconditioners. No free lunch. > >> > >> Rob > > > > This wouldn't require anything on the FFC end. It would just require a > > new C++ class which subclasses either of the Krylov matrices (or maybe > > a new GenericKrylovMatrix) that takes a linear form (like your 'a' > > above) to the constructor and calls assemble() in the overloaded mult(). > > > > This should be easy to add. > > > > -- > > Anders > > > > > > -----BEGIN PGP SIGNATURE----- > > Version: GnuPG v1.4.9 (GNU/Linux) > > > > iEYEARECAAYFAknYbQkACgkQTuwUCDsYZdHiCgCeOk8lUh47at3BIt9E7/Xkinw1 > > 3KEAniQRFbDbirrEOgNznCFdPaLfKD9E > > =YC3r > > -----END PGP SIGNATURE----- > > > > _______________________________________________ > > DOLFIN-dev mailing list > > [email protected] > > http://www.fenics.org/mailman/listinfo/dolfin-dev > > > > > _______________________________________________ > DOLFIN-dev mailing list > [email protected] > http://www.fenics.org/mailman/listinfo/dolfin-dev >
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