On Mon, Oct 6, 2014 at 9:34 AM, Roy Stogner <[email protected]> wrote:
> > On Mon, 6 Oct 2014, Rodrigo Broggi wrote: > > const Real norm_delta = last_nonlinear_soln->l2_norm(); >> >> This way I'am actually computing the l2 vector norm not the function >> norm, is that right? >> > > Right. > > To compute the actual functional norm I should have to associate it >> to the system. >> > > With calculate_norm(), right. > > Is there any particular reason to consider the vector norm and not the >> functional one? >> > > Two reasons to default to the vector norm: > > Speed. Calculating l2 is just a loop over DoFs; calculating L2 > also requires an internal loop over quadrature points. > > Physics independence. There are definitely good arguments to be made > for using a functional norm for your stopping criterion instead, but > *which* norm you want usually depends on what your problem is. Even > "the" H1 norm is dependent on your choice of units unless you > nondimensionalize. > Ah, I can almost hear Professor Demkowicz saying "all norms on finite dimensional vector spaces are equivalent" :-) -- John ------------------------------------------------------------------------------ Slashdot TV. Videos for Nerds. Stuff that Matters. http://pubads.g.doubleclick.net/gampad/clk?id=160591471&iu=/4140/ostg.clktrk _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
