Hi Bradley
The FEValuesExtractors::Vector is for first-order tensors as you say and not
arbitrary size vectors.
You can however create a std::vector of FEValuesExtractors::Scalar extractors.
The following example had displacement (\in R^dim), \gamma (\in R^
n_slip_systems) and yield ( \in R^ n_slip_systems) as nodal variables:
// generate displacement, slip and yield shape function views
const FEValuesExtractors::Vector displacements_fe(0);
std::vector<FEValuesExtractors::Scalar> gamma_fe;
std::vector<FEValuesExtractors::Scalar> yield_fe;
for (unsigned int alpha = 0; alpha < n_slip_systems; alpha++) {
gamma_fe.push_back(FEValuesExtractors::Scalar(deal_II_dimension +
alpha));
yield_fe.push_back(FEValuesExtractors::Scalar(deal_II_dimension +
n_slip_systems + alpha));
}
So you can do what you want without extending deal.ii. The extension to include
this functionality in the library would be pretty easy.
Regards
Andrew
On 16 Sep 2010, at 8:35 AM, Thomas Wick wrote:
> Hi Bradley,
>
>
> On Wed, 15 Sep 2010, Wolfgang Bangerth wrote:
>
>>
>> Bradley,
>>
>>> A motivating example would be Landau-Lifshitz-Gilbert equation which models
>>> magnetization in a solid.
>
> This is a coupled problem, isn't it? Normally, as Wolfgang already explained,
> all existing classes are sufficient for such problems. For instance, if you
> look for 3 solution variables v, u, and p, then you have to specify their
> dimensions. In 3D you get: v_x , v_y , v_z , u_x, u_y ,u_z, and scalar p.
>
> With the extractors it looks like:
>
> const FEValuesExtractors::Vector velocities (0);
> const FEValuesExtractors::Vector displacements (dim); const
> FEValuesExtractors::Scalar pressure (dim+dim);
>
> where dim==3.
>
>
>>
>> What I really meant is: how would you use such an arbitrary-dimensional
>> vector? For example, what would be the value_type of this class be for the
>> case you consider? Why are the existing classes insufficient? Etc.
>>
>> Best
>> W.
>>
>> -------------------------------------------------------------------------
>> Wolfgang Bangerth email: [email protected]
>> www: http://www.math.tamu.edu/~bangerth/
>> _______________________________________________
>> dealii mailing list http://poisson.dealii.org/mailman/listinfo/dealii
>>
>
>
> Best regards,
>
> Thomas
> _______________________________________________
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