Anders Logg wrote:
> On Wed, Dec 17, 2008 at 12:15:38AM +0000, Garth N. Wells wrote:
>> I'm running into some problems with the new Function design when trying
>> to update a solver. I'll try to sketch the issue as simply as possible.
>>
>> Function v;
>> Function u, p;
>>
>> // First form for U = (u, p)
>> FirstBilinearForm a_1(V1, V1);
>> FirstLinearForm L_1(V1);
>> LinearPDE pde_first(a_1, L_1);
>>
>> // Second form which depends on u
>> SecondBilinearForm a_2(V2, V2);
>> SecondLinearForm L_2(V2, u);
>> LinearPDE pde_second(a_2, L_2);
>>
>> Function U;
>> for(uint i = 0; i < 10; ++i)
>> {
>> pde_first.solve(U);
>>
>> // This step breaks down because FunctionSpaces don't match
>> u = U[0];
>> p = U[1];
>>
>> pde_second.solve(v);
>> }
>>
>> The problem is in assigning Functions since we now check the FunctionSpace.
>
> Which check is it that fails?
>
The check on the FunctionSpace in
const Function& Function::operator= (const Function& v)
fails. Should we have "Function::operator=" assign a Function object, or
just the values of a Function (as it does now)? Also, should we have a
const Function& operator= (const SubFunction& v);
function?
I also tried
FunctionSpace V;
SubSpace Vu(0);
SubSpace Vp(1);
Function U(V);
Function u(Vu);
Function p(Vp);
which doesn't work because I guess a new FunctionSpace is created for
each SubSpace.
Should a FunctionSpace "own" its subspaces so one could do
MyFunctionSpace V(mesh);
FunctionSpace& sub_space V[0];
and be sure for always getting the same subspace rather than creating
copies.
>> To get around this, I tried
>>
>> FunctionSpace V(mesh);
>> Function U(V);
>> Function u = U[0];
>> Function p = U[1];
>>
>> which throws an exception because U does not have a vector.
>
> What if we remove the check in operator[] and then in the constructor
> that gets a SubFunction we rely on v.v.vector() which (after Martin's
> fix from yesterday) will always return a vector with the dofs
> (possibly interpolated if there were no dofs before).
>
Yes, that would make sense if the new additions are working.
Garth
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> 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
