Well, we have the BoundingBoxTree, which similarly caches data that speed up certain operations. We also have a Solver class and a free function solve, an Assembler class and a free function assemble. Similarly we could have a free function assign, which construct a FunctionAssign object. However there is a lot of data which could be reused in the FunctionAssign object. If a user want to utelize that he should instantiate the object and use that in his code.
Johan On Tue, Sep 24, 2013 at 10:27 AM, Anders Logg <l...@chalmers.se> wrote: > Is it possible to solve this without introducing the design pattern > with a class FunctionAssigner? We have been careful to avoid this in > other places. > > -- > Anders > > > > On Mon, Sep 23, 2013 at 07:20:03PM +0200, Johan Hake wrote: > > I am working on sub-function assignment. To facilitate caching of dof > indices > > for a particular assignment combination I suggest introducing a > > FunctionAssigner class which caches the necessary indices (dofs) for the > whole > > domain. > > > > Something like: > > > > mesh = UnitSquareMesh(10,10) > > V = FunctionSpace(mesh, "CG", 1) > > VV = V*V > > > > # Assign two scalar functions to the components of a mixed function > > assigner0 = FunctionAssigner([V, V], VV) > > > > # Assign components of a mixed function to scalar Functions > > assigner1 = FunctionAssigner(VV, [V, V]) > > > > # Assign a scalar function to a component of a mixed function > > assigner2 = FunctionAssigner(V, VV.sub(1)) > > > > u0, u1 = Function(V), Function(V) > > U = Function(VV) > > > > Then in some time loop: > > > > while t < tstop: > > ... > > assigner0.assign([u0, u1], U) > > ... > > assigner1.assign(U, [u0, u1]) > > ... > > assigner2.assign(u0, U.sub(1)) > > > > In C++ the equivalent to a list of Foo will be a std::vector of shared > Foos. > > > > Comments? > > > > By using sub spaces and sub functions we avoid using indices in the > interface, > > which I think is neat. However, there are some limitations with the > present > > interface: > > > > 1) The FunctionAssigner needs to have access to the local ownership > range of a > > sub dofmap, but that is not possible as it is set to 0,0 during > construction. > > Could we add a proper local ownership range to a sub dofmap? > > 2) The FunctionAssigner need to be able to access the private _vector of > a > > parent Function during the assignment, as calling subfunc.vector() > raises an > > error. This can be fixed by a friend statement. Is that acceptable? > > > > Johan > > > _______________________________________________ > > fenics mailing list > > fenics@fenicsproject.org > > http://fenicsproject.org/mailman/listinfo/fenics > >
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