Anders Logg wrote:
> On Wed, Apr 09, 2008 at 06:14:35PM +0200, Ola Skavhaug wrote:
>> Dag Lindbo skrev den 09/04-2008 følgende:
>>> Hello again!
>>>
>>> Why is it not possible any longer to get the Vector associated with a
>>> Function? E.g:
>>>
>>> #include <dolfin.h>
>>> using namespace dolfin;
>>>
>>> int main()
>>> {
>>> Function u;
>>> Vector& v = u.vector();
>>> }
>> int main()
>> {
>> Function u;
>> Vector v;
>> v = u.vector();
>> return 0;
>> }
>>
>> Should work. A Function returns a GenericVector reference, and the Vector
>> reference needs to be a Vector. Then the operator= in Vector is applied in
>> the
>> assignment.
>>
>> Ola
>
> I don't think one should need to make a copy of the vector. It should
> work to either use the vector you get by calling vector() directly,
> for example
>
> solve(A, u.vector(), b); // Doesn't work currently but it should!
>
> You may also do
>
> GenericVector& x = u.vector();
>
This works. Can someone remind me how to convert a GenericVector into
the underlying vector type( e.g. a uBlasVector or a PETScVector)?
Garth
> The thing that's changed is that a Function saves its data in a
> GenericVector which can be anything, a PETScVector, a uBlasVector,
> an EpetraVector, or even your own implementation of a vector class.
>
> The class Vector is a particular implementation of a Vector, decided
> at compile-time depending on how you have configured DOLFIN. If you
> compile with PETSc, then it's a wrapper for a PETScVector, otherwise
> it's a wrapper for a uBlasVector.
>
> Some work needs to be done to get all the linear algebra behave well
> in both Python and C++. This will likely take some weeks so we might
> not be able to fix everything before the release.
>
> (I will add the solve() problem above to the TODO list.)
>
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