Hello,
another forward to my problem: I can only combine element types with the
same number of vector components (staketrace below)!
That was the basic difference in my physical model of the two domains...
So do I need to use hp after all - I mean if I use the same FE types on
both subareas, just arranging the cell matrices differently (Dispensable
dofs are just ignored and set to zero.), it would be just like using
"simple" FESystems with one DoFHandler and setting different material_id
s for the cells, right?
Or what other advantage do I have with hp description in that case?
Best
Till
t...@lepc:~/dealfolder/deal.II/examples/elastic_dh$ make run
============================ Remaking Makefile.dep
==============debug========= step-8.cc
============================ Linking step-8
============================ Running step-8
--------------------------------------------------------
An error occurred in line <67> of file <source/hp/fe_collection.cc> in
function
void dealii::hp::FECollection<dim, spacedim>::push_back(const
dealii::FiniteElement<dim, spacedim>&) [with int dim = 2, int spacedim =
2]
The violated condition was:
new_fe.n_components() == finite_elements[0]->n_components()
The name and call sequence of the exception was:
ExcMessage ("All elements inside a collection need to have the "
"same number of vector components!")
Additional Information:
All elements inside a collection need to have the same number of vector
components!
Stacktrace:
-----------
#0 /home/till/dealfolder/deal.II/lib/libdeal_II_2d.g.so.6.3.pre:
dealii::hp::FECollection<2, 2>::push_back(dealii::FiniteElement<2, 2>
const&)
#1 ./step-8: ElasticProblem<2>::ElasticProblem()
#2 ./step-8: main
--------------------------------------------------------
make: *** [run] Aborted
-------- Weitergeleitete Nachricht --------
Von: Wolfgang Bangerth <[email protected]>
An: [email protected]
Kopie: Till Heinemann <[email protected]>, Markus Bürg <[email protected]>, Duc
Vu <[email protected]>
Betreff: Re: [deal.II] assembling a single system from two DoFHandlers
Datum: Thu, 3 Dec 2009 08:08:38 -0600
> But is this FECollection policy only valid in hp namespace? As far as
> I've not quite fully understood what this hp FEM does, but taking a
> glimpse at the description it might be designed to use collections of FE
> types and adaptively use them.
In the hp FEM method, you typically use elements of different polynomial order
on different cells. To do this, the FECollection stores all elements that you
might want to use, and on each cell set the active_fe_index flag to indicate
which element of the collection should be used on this one cell. Note that
this collection then has a totally different meaning than FESystem which
constructs *vector-valued* elements from simpler elements.
Now, what Markus' suggestion means is that while the idea of the hp namespace
was to use different polynomial degrees on different cells, there is nothing
that prevents you from using this mechanism to also use different finite
elements for different physics on cells that belong to different subregions.
That wasn't the initial intention when writing the hp stuff, but it's a valid
application of the code.
> If it's not possible just to do sth similar with a FESystem, then I
> guess I'll start getting into that hp stuff.
Again, the FESystem is meant for an entirely different purpose, namely
coupling simpler elements into a vector-valued element.
W.
-------------------------------------------------------------------------
Wolfgang Bangerth email: [email protected]
www: http://www.math.tamu.edu/~bangerth/
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