On Tuesday 04 November 2008 14:11:55 Anders Logg wrote: > On Tue, Nov 04, 2008 at 01:59:33PM +0100, Johan Hake wrote: > > On Tuesday 04 November 2008 13:15:51 Anders Logg wrote: > > > On Mon, Nov 03, 2008 at 10:38:40PM +0100, Anders Logg wrote: > > > > On Mon, Nov 03, 2008 at 06:25:18PM +0100, Martin Sandve Alnæs wrote: > > > > > 2008/11/3 Anders Logg <[EMAIL PROTECTED]>: > > > > > > On Mon, Nov 03, 2008 at 03:55:31PM +0000, Garth N. Wells wrote: > > > > > >> Anders Logg wrote: > > > > > >> > On Mon, Nov 03, 2008 at 02:38:36PM +0000, Garth N. Wells wrote: > > > > > >> >> Anders Logg wrote: > > > > > >> >>> On Mon, Nov 03, 2008 at 11:22:26AM +0000, Garth N. Wells wrote: > > > > > >> >>>> Anders Logg wrote: > > > > > >> >>>>> On Sun, Nov 02, 2008 at 06:29:25PM +0000, Garth N. Wells wrote: > > > > > >> >>>>>> Anders Logg wrote: > > > > > >> >>>>>>> On Sun, Nov 02, 2008 at 05:52:21PM +0000, Garth N. Wells > > > > wrote: > > > > > >> >>>>>>>> Do we want to insist that Dirichlet bc functions that > > > > > >> >>>>>>>> do not appear inside a form are constructed with a > > > > > >> >>>>>>>> FunctionSpace? DirichletBC is supplied with a > > > > > >> >>>>>>>> FunctionSpace, so if the bc Function does not have a > > > > > >> >>>>>>>> FunctionSpace, we could attach one automatically. > > > > > >> >>>>>>>> > > > > > >> >>>>>>>> Garth > > > > > >> >>>>>>>> _______________________________________________ > > > > > >> >>>>>>>> DOLFIN-dev mailing list > > > > > >> >>>>>>>> [email protected] > > > > > >> >>>>>>>> http://www.fenics.org/mailman/listinfo/dolfin-dev > > > > > >> >>>>>>> > > > > > >> >>>>>>> I think this is already handled. Look in the Poisson > > > > > >> >>>>>>> demo. It uses a Constant to set the BC and it does not > > > > > >> >>>>>>> have a FunctionSpace attached to it. The DirichletBC > > > > > >> >>>>>>> class now uses its own FunctionSpace rather than the one > > > > > >> >>>>>>> that the Function has (if any). There is a check (in > > > > > >> >>>>>>> DirichletBC::check()) that checks that the FunctionSpace > > > > > >> >>>>>>> for the Function is the same as the one in the > > > > > >> >>>>>>> DirichletBC. > > > > > >> >>>>>> > > > > > >> >>>>>> It works for Constant, but not for Functions. I was > > > > > >> >>>>>> getting an error when Function::interpolate is called. > > > > > >> >>>>>> Function::interpolate leads to eval being called, in > > > > > >> >>>>>> which case there is a test for the FunctionSpace which > > > > > >> >>>>>> fails. Constant provides its own eval and therefore > > > > > >> >>>>>> doesn't have a problem. > > > > > >> >>>>>> > > > > > >> >>>>>> For now, I've added a test in DirichletBC for the > > > > > >> >>>>>> FunctionSpace. What we can add is an attach function if > > > > > >> >>>>>> there is no FunctionSpace associated. > > > > > >> >>>>>> > > > > > >> >>>>>> Garth > > > > > >> >>>>> > > > > > >> >>>>> In which demo does this show up? Is there a simple way I > > > > > >> >>>>> can comment something out to reproduce the error so I > > > > > >> >>>>> understand what goes wrong? > > > > > >> >>>> > > > > > >> >>>> Look at /demo/nls/nonlinearpoisson/cpp. > > > > > >> >>>> > > > > > >> >>>> If you change > > > > > >> >>>> > > > > > >> >>>> DirichletBoundaryCondition g(V, t); > > > > > >> >>>> > > > > > >> >>>> to > > > > > >> >>>> > > > > > >> >>>> DirichletBoundaryCondition g(t); > > > > > >> >>>> > > > > > >> >>>> it will break down. > > > > > >> >>>> > > > > > >> >>>> Garth > > > > > >> >>> > > > > > >> >>> ok I see the problem now. > > > > > >> >>> > > > > > >> >>> The problem is a user may choose to either overload a scalar > > > > > >> >>> eval function or a tensor eval function and we need to > > > > > >> >>> decide which one after the callback from > > > > > >> >>> ufc::function::evaluate(). If the FunctionSpace is not > > > > > >> >>> known, we can't decide which one to pick. > > > > > >> >>> > > > > > >> >>> If we insist that one should be able to pass a Function > > > > > >> >>> without a FunctionSpace to a DirichletBC, then we must > > > > > >> >>> remove the scalar eval function. > > > > > >> >> > > > > > >> >> Fine with me. I think that it makes things simpler because > > > > > >> >> the eval interface remains the same for all user-defined > > > > > >> >> functions. > > > > > >> >> > > > > > >> >> Garth > > > > > >> > > > > > > >> > ok. It will also look the same as in Python. > > > > > >> > > > > > >> We discussed recently passing an object to eval() which contains > > > > > >> some data. It would be useful the object also carried > > > > > >> information on the rank and dimension of the function to allow > > > > > >> checks and switching between 1D/2D/3D problems. > > > > > >> > > > > > >> Garth > > > > > > > > > > > > Yes, this would be nice, but it won't work as long as we don't > > > > > > require that a Function always has a FunctionSpace. We could add > > > > > > some new classes to handle error checking and data for > > > > > > user-defined Functions: > > > > > > > > > > > > void eval(Values& values, Data& data) > > > > > > { > > > > > > values[0] = sin(data.x[0]); > > > > > > } > > > > > > > > > > > > The class Values could check that data is not assigned to any > > > > > > illegal indices and it could also check that all values have been > > > > > > assigned etc, but if the Function does not know its > > > > > > FunctionSpace, this can't be done. > > > > > > > > > > > > Another complication related to this but also to the > > > > > > thread-safety of cell() and facet() is that UFC gets in the > > > > > > middle of the call sequence: > > > > > > > > > > > > assemble() > > > > > > > > > > > > |--> Function::interpolate() > > > > > > | > > > > > > |--> FiniteElement::evaluate_dof() > > > > > > | > > > > > > |--> ufc::finite_element::evaluate_dof > > > > > > | > > > > > > |--> ufc::function::evaluate() > > > > > > | > > > > > > |--> Function::eval() > > > > > > > > > > > > Since eval() is called from the generated UFC code, any arguments > > > > > > like cell and facet passed from the assembler will be lost on the > > > > > > way. > > > > > > > > > > > > Should we extend the UFC interface to allow sending a void* to > > > > > > evaluate_dof which it will propagate to evaluate()? > > > > > > > > > > That's possible, but not very safe. > > > > > > > > > > A typesafe alternative is that dolfin::Function doesn't inherit > > > > > ufc::function, but a ufc::function subclass is created which has a > > > > > dolfin::Function which it calls and a dolfin::Data & which it sends > > > > > in the call. Then we avoid ufc complications in dolfin::Function, > > > > > and one such wrapper function can be created for each thread. > > > > > It doesn't really add any more function calls, since it replaces > > > > > the existing ufc::function::evaluate in the call stack you wrote > > > > > above. > > > > > > > > Sounds good. I'll try something like this. > > > > > > This is now implemented. Take a look in Function::interpolate(), > > > > Should it be called FunctionData instead? > > Data is shorter and means less to write in the eval() functions (so we > can make these look as simple as possible).
"Make everything as simple as possible, but not simpler." I think writing Function in addition to Data wont hurt. > We could possibly make it a nested class of Function (Function::Data) > but that might require that one writes Function::Data in the > overloaded eval functions and it might be troublesome for SWIG. > > > As Data is implemented now it cannot be changed after creation, i.e., you > > cannot set _facet or _cell. Would it be benefitial to cache the Data > > object and the dofs, which both are created for each call of interpolate? > > Creating it each time is exactly what makes interpolate() thread-safe > now which it wasn't before. Ahh... Johan _______________________________________________ DOLFIN-dev mailing list [email protected] http://www.fenics.org/mailman/listinfo/dolfin-dev
