Bruno -

Thank you for your help. I see what you are saying. In this way I would 
need to make sure I have the same number of gauss points as nodes in the 
finite element since deal.II will assume that the stress degrees of freedom 
are associated with the nodes. For now I don't believe this is too strict 
of a limitation for me since I will likely choose the quadrature rule such 
that the number of quadrature points is equal to the number of nodes 
anyways. Perhaps there is a better way to handle this situation but I will 
try this for now. Thanks again!


On Wednesday, March 7, 2018 at 11:04:33 AM UTC-5, Bruno Turcksin wrote:
> Jonathan,
> 2018-03-07 10:43 GMT-05:00 Jonathan Russ < 
> <javascript:>>:
>> Thank you for your fast reply. I'm sorry I'm not doing a great job of 
>> explaining this. Here is an example from elasticity that illustrates what I 
>> would like:
>> In this case there are displacement degrees of freedom at the nodes but 
>> the stress is a quantity typically derived from the displacements. However, 
>> one could make the stress an independent degree of freedom at the gauss 
>> points. 
>> So, in the element there would be displacement degrees of freedom at the 
>> nodes and stress degrees of freedom at the gauss points. Does this make 
>> sense?
> I don't think there is a way to do that in deal unless you can split your 
> finite elements, i.e., you have one FE_Q for the displacement and another 
> FE_Q for the stress. Then, you can use FESystem. But do I understand 
> correctly that the stress is not describe by any finite element but you 
> would like to use dof_handler to help you manage some data. In that case, I 
> think that using a FESystem should work, you just will never call FEValues 
> for the stress since you don't care about the associated finite element but 
> the dof_handler will associate a degree of freedom to each quadrature point.
> Best,
> Bruno

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