[dune-pdelab] Writing subtree of a CompositeGridFunctionSpace to VTK

[Oliver Sander]

Hi Christian,
I will try to do that.  How do I get the equivalent of

  typedef GridOperator::Traits::Domain V;

(with the istl backend) directly from the Composite space?
My MWE will not be very M if I have to keep the GridOperator.

Thanks,
Oliver

Am 25.06.2015 um 16:16 schrieb Christian Engwer:
> Hi Oli,
> 
> can please cookup a MWE, which we can use to track down the problem?
> 
> Thanks
> Christian
> 
> On Tue, Jun 23, 2015 at 12:46:50PM +0200, Oliver Sander wrote:
>>>>> As the SubTree is now an object on its own and doesn't exhibit the
>>>>> VectorGridFunctionSpace tag anymore the transformation doesn't detect
>>>>> the vector type of your GFS anymore.
>>>>
>>>> Hmm, why should that tag disappear?  On first sight this sounds like a bug to me,
>>>> but I'm sure in a second you will tell me that there is a good reason for it :-)
>>>
>>> I'm not totally sure how the transformations work in the end, the code
>>> is quite involved, but the quick answer is if consider
>>>
>>> struct A
>>> {
>>> 	typdef X tag;
>>> };
>>>
>>> and
>>>
>>> template<typename T>
>>> struct S
>>> {
>>> 	A a;
>>> };
>>>
>>> S<A> will not contain the tag anymore. The TypeTree::ProxyNode is used
>>> to wrap the actual node and perhaps that is the place where things go wrong.
>>
>> So we need to ask the master.  Steffen, are you there?
>>
>>
>>>
>>>>> You would have to abjust the
>>>>> transformations employed when constructing the SubGFS. I'm not sure
>>>>> how difficult it is. As a work-around you can merge them again in
>>>>> paraview, using the calculator:
>>>>>
>>>>> Result = iHat * displacement0 + jHat * displacement1 + kHat * displacement2
>>>>
>>>> I'd dislike doing this, but it seems like I have to:  in 3d my overall space has
>>>> 8 components, and the VTKWriter flat-out refuses to write that.
>>>
>>> I just saw an alternative possibility...
>>>
>>> you can pass a predicate to addSolutionToVTKWriter. the predicate is
>>> called with a local function space and returns true if the data
>>> associated with this space should be written. By this you could call
>>> addSolutionToVTKWriter for the whole GFS and use the predicate to
>>> filter the subspaces.
>>
>> That sounds good.  Do you have example code that shows how to do this?
>>
>> Thanks,
>> Oliver
>>
>>>
>>> Christian
>>>
>>
>>
> 
> 
> 


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