[Dune] jacobian construction

Wed Jun 22 18:58:34 CEST 2016

Hi Martin,
I understand your explanation but I'm far from understanding how to debug my problem.
I accelerate the execution of the "small" code I sent you some days ago, but because of parametrization I cannot make it smaller.
I tried to better understand the problem, isolating one intersection of my conforming grid.
I remark that the grid is a coarse grid, it is 3D ALUCubeGrid and a GeometryGrid is built introducing a Q3 parametrization.
I'm still working with dune 2.3.0 and ALUGrid 1.52b. I'm porting the code to dune 2.4.1, encountering some problem.

The problematic intersection is the one between element 42 and 43, its indices are 4 and 5 respectively.
Element 42 and 43 store their corner in the right way, not only they are what I expect but there is coherence between the 2 elements

Corners element 42 
gcorner 0 2.0000000000000000 0.2598190000000000 0.0000000000000000 
gcorner 1 2.0000000000000000 0.2598189999999993 0.2000000000000000 
gcorner 2 1.9806379930000000 0.2548077446999999 0.0000000000000000 
gcorner 3 1.9806379930000000 0.2548077446999999 0.2000000000000000 
gcorner 4 2.0000000000000000 0.2588190000000001 0.0000000000000000 
gcorner 5 2.0000000000000000 0.2588190000000007 0.2000000000000000 
gcorner 6 1.9806379930000000 0.2538077447000000 0.0000000000000000 
gcorner 7 1.9806379930000000 0.2538077446999998 0.2000000000000000 

Corners element 43
gcorner 0 2.0000000000000000 0.2608364441000000 -0.0000000000000000 
gcorner 1 2.0000000000000000 0.2608364440999995 0.2000000000000000 
gcorner 2 1.9806379930000000 0.2558252375000000 0.0000000000000000 
gcorner 3 1.9806379930000000 0.2558252374999995 0.2000000000000000 
gcorner 4 2.0000000000000000 0.2598190000000000 0.0000000000000000 
gcorner 5 2.0000000000000000 0.2598189999999993 0.2000000000000000 
*gcorner 6 1.9806379930000000 0.2548077446999999 0.0000000000000000 
*gcorner 7 1.9806379930000000 0.2548077446999999 0.2000000000000000 

Paying attention to them we can see correspondence between nodes 0,1,2,3 of element 42 and nodes 4,5,6,7 of element 43

Therefore I asked intersection corners to both the elements, expecting exactly the same corners. But

Corners of intersection 4 of element 42
gcorner 0 2.0000000000000000 0.2598190000000000 0.0000000000000000
gcorner 1 1.9806379930000000 0.2548077446999999 0.0000000000000000
gcorner 2 2.0000000000000000 0.2598189999999993 0.2000000000000000
gcorner 3 1.9806379930000000 0.2548077446999993 0.2000000000000000

Corners of intersection 5 of element 43
gcorner 0 2.0000000000000000 0.2598190000000000 0.0000000000000000
*gcorner 1 1.9806379930000000 0.2548077934000000 0.0000000000000000
gcorner 2 2.0000000000000000 0.2598189999999995 0.2000000000000000
*gcorner 3 1.9806379930000000 0.2548077933999995 0.2000000000000000

I highlight using stars the problematic corners.
Element 42 has no problem, while there's no coherence between the intersection 5 corners of 43 and their relative element corners.
If you want I can give you the faster code, but it uses dune 2.3.0.
But it would be better if you can drive me to point of dune or ALUGrid where the problem stems.
In the meanwhile, I can continue my 2.4.1 porting.
In any case, I use in the real code the subgrid module and I'm having some problem in building a basic project using it.

Thank you very much for any hint or even just for your attention.

Best regards,
Marco

________________________________________
Da: Martin Nolte <nolte at mathematik.uni-freiburg.de>
Inviato: lunedì 20 giugno 2016 20.05.53
A: Marco Cisternino; dune at dune-project.org
Oggetto: Re: [Dune] jacobian construction

Hi Marco,

there is no call to jacobianTransposed. The jacobianTransposed is a by-product
of the method affine( jacobianTransposed ) on the MultiLinearGeometry.

The affine check works as follows:
- a point geometry is always affine; its jacobianTransposed is trivial.
- a prism is affine if and only if the base geometry is affine
- a prism over some geometry is affine if
   + top and bottom geometry are both affine
   + the jacobian of top and bottom geometry equals

You see, I potentially need the jacobianTransposed on all "subgeometries".
Therefore, as long as the geometry is affine, I have to compute it along the
way. In contrast to jacobianTransposed, I have the jacobianTransposed of the
base geometry or the bottom geometry already available. Therefore, the method
jacobianTransposed is not called at all.

Best,

Martin

PS: Please keep the conversation on the mailing list.

On 06/20/2016 06:33 PM, Marco Cisternino wrote:
> Hi Martin,
> If I have understood CachedMultiLinearGeometry in the affine case constructs the jacobianTransposed calling implicitly the constructor of the base class, i.e. MultiLinearGeometry and when it is affine the constructor of MultiLinearGeometry is called and somewhere (but I cannot see where...) this constructor is called
>
> jacobianTransposed< false >( topologyId(), integral_constant< int, mydimension >(), cit, ctype( 1 ), local, ctype( 1 ), jacobianTransposed_ );
>
> right?
>
> Thanks,
> Marco
> ________________________________________
> Da: Martin Nolte <nolte at mathematik.uni-freiburg.de>
> Inviato: lunedì 20 giugno 2016 18.09.14
> A: Marco Cisternino
> Oggetto: Re: [Dune] jacobian construction
>
> Hi Marco,
>
> I guess your question is where the CachedMultiLinearGeometry computes its
> jacobianTransposed. In the case of an affine mapping, this is done in the
> constructor. Otherwise it is not cached at all.
>
> When checking whether a MultiLinearGeometry is affine, you compute the
> jacobianTransposed as a by-product.
>
> Best,
>
> Martin
>
> On 06/20/2016 11:57 AM, Marco Cisternino wrote:
>> Good morning duners,
>> I'm debuging my code and I have an incoherence between the corners stored in the geometry of the element and its jacobianTransposed: the code doesn't reproduce stored corners when it re-computes them by using the jacobian.
>> I'm using Dune 2.3.0 and ALUGrid 1.52b, setting a GeometryGrid with a element-by-element parametrization.
>> I would like to know where, when and how the jacobianTransposed is computed for the first time.
>>
>> Thanks,
>> Marco
>>
>> _______________________________________________
>> Dune mailing list
>> Dune at dune-project.org
>> http://lists.dune-project.org/mailman/listinfo/dune
>>
>
> --
> Dr. Martin Nolte <nolte at mathematik.uni-freiburg.de>
>
> Universität Freiburg                                   phone: +49-761-203-5630
> Abteilung für angewandte Mathematik                    fax:   +49-761-203-5632
> Hermann-Herder-Straße 10
> 79104 Freiburg, Germany
>

--
Dr. Martin Nolte <nolte at mathematik.uni-freiburg.de>

Universität Freiburg                                   phone: +49-761-203-5630
Abteilung für angewandte Mathematik                    fax:   +49-761-203-5632
Hermann-Herder-Straße 10
79104 Freiburg, Germany