Anders Logg wrote: > On Mon, Apr 21, 2008 at 09:35:30PM +0200, Dag Lindbo wrote: >>>> Why do I care? I'm looking at the current state of the LinearPDE class. >>>> Here, the solution vector is a member function, and the solution >>>> Function is initialized with a reference to this vector. I.e. the >>>> LinearPDE (not the DiscreteFunction) owns the solution vector. This is >>>> of course a problem if the LinearPDE goes out of scope before the >>>> solution function (bug 24). It is also a bit counter-intuitive. >>>> >>>> If it was possible to do an initialization like above, then the solve() >>>> method would simply do >>>> u.init(mesh, form, 1); >>>> GenericVector& x = u.vector(); >>>> <solve> >>> There is a member local_vector in DiscreteFunction that could be used >>> for this. If this is nonzero, then the DiscreteFunction owns its data. >>> >>> See if you can figure out a good way for the DiscreteFunction to know >>> that it should take responsibility for the vector here. >>> >> Right... I don't see how to do this without breaking the encapsulation of >> both Function and DiscreteFunction (making LinearPDE friend in both). >> Bundle attached. >> >> Garth, does this look OK? >> >> In essence, the member x is removed from the LinearPDE class. in >> LinearPDE::solve I do >> >> (...) >> Vector b; >> Vector* x = new Vector(); >> (... call solver etc) >> >> u.init(mesh, *x, a, 1); >> DiscreteFunction& uu = dynamic_cast<DiscreteFunction&>(*u.f); >> uu.local_vector = x; >> >> /Dag > > Looks like a good temporary solution to me. > > I expect when we're done and happy with the linear algebra classes > (which should be soon), we will have a similar party with the function > classes... :-) >
The fact that the pointer to x goes out of scope and trusts the DiscreteFunction to clean up the vector makes me a bit queasy (this can probably break in the future, causing a big leak). You should probably verify independently that nothing broke because of this revised LinearPDE (but for me it has been working nicely today). On a more general note, I'm pretty happy with the state of the LA now that op[] is back and the down_cast<Foo> mechanism has been explained. As a benchmark I ran a Inc. Navier-Stokes solver (based on the old module, which uses a lot of 'manual' LA) and got a modest slowdown: (tip yesterday) 53.071u 6.708s (0.7.2) 50.803u 1.700s It may also be worth mentioning that I got the same numerical values (for some residual norm) even after hundreds of time steps. /Dag _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
