[Dune] Reference tetrahedron, again

Adrian Burri burriad at mathematik.uni-freiburg.de
Thu Jul 21 15:40:55 CEST 2005


Well, I think the point is that there is no "correct" ordering, so we're 
completely free to choose it to our liking. I don't have a clue where 
the numbering convention in ReferenceTopologySet comes from, but I think 
it is nice for two reasons:
- I used it in my implementation and don't need to change anything if we 
stick to it
- the orientation of all faces is the same (inward pointing normal)

I think it is not up to me to decide whether this  is the best possible 
choice, but if  noone has any objections against it, I would declare it 
as the Dune standard.

Cheers

Adi

P.S. An algorithmic definition of the numbering is this: Given the three 
face vertices, start with the smallest available index and choose the 
rest so that the orientation of all faces is the same (inward pointing, 
in this case).

Sreejith Pulloor Kuttanikkad wrote:

>On Thu, Jul 21, 2005 at 02:35:29PM +0200, Adrian Burri wrote:
>  
>
>>Hi,
>>
>>the Dune-homepage says nothing about the numbering of the vertices on 
>>faces, but as you can see from the attached program and output, the 
>>numbering in the ReferenceSimplex changed from the way it was in the 
>>ReferenceTopologySet. Can we stick to the way it was in the 
>>ReferenceTopologySet? (I use this numbering convention heavily in 
>>ALU3dGrid and would like to leave it as is...)
>>    
>>
>
>
>Infact I had no idea how the numbering of the vertices on faces done
>(basic rule on local numbering of vertices on faces) and thats why the
>mismatch. could you please explain the basic rule of the numbering
>convention you following so that i could correct them.
>
>sreejith
>
>  
>
>>Ciao
>>
>>Adi
>>    
>>
>
>  
>
>>//- System includes
>>#include <iostream>
>>
>>//- Dune includes
>>#include <dune/grid/common/reftopology.hh>
>>#include <dune/grid/common/referenceelements.hh>
>>
>>using namespace Dune;
>>
>>int main() {
>>  int n;
>>  const int* faceIdx;
>>
>>  const int nFacesTet = 4;
>>  const int nFacesHexa = 6;
>>
>>  std::cout << "Test tetrahedra:" << std::endl;
>>  std::cout << "----------------" << std::endl;
>>
>>  ReferenceSimplexContainer<double, 3> simplexContainer;
>>  const ReferenceSimplex<double, 3>& referenceTetrahedron = 
>>    simplexContainer(tetrahedron);
>>
>>  for (int face = 0; face < nFacesTet; ++face) {
>>    ReferenceTopologySet::getSubEntities<1,3>(tetrahedron, face, faceIdx, n);
>>    std::cout << "Face " << face << ":" << std::endl;
>>    std::cout << "(ReferenceTopologySet) "
>>              << "{ " << faceIdx[0] 
>>              << ", " << faceIdx[1] 
>>              << ", " << faceIdx[2] 
>>              << " }" << std::endl;
>>
>>    std::cout << "(ReferenceSimplex) "
>>              << "{ " << referenceTetrahedron.subentity(face, 1, 0, 3)
>>              << ", " << referenceTetrahedron.subentity(face, 1, 1, 3)
>>              << ", " << referenceTetrahedron.subentity(face, 1, 2, 3)
>>              << " }" << std::endl;
>>    
>>  }
>>
>>  std::cout << std::endl;
>>  std::cout << "Test hexahedra:" << std::endl;
>>  std::cout << "---------------" << std::endl;
>>
>>  ReferenceCubeContainer<double, 3> cubeContainer;
>>  const ReferenceCube<double, 3>& referenceCube =
>>    cubeContainer(cube);
>>  
>>  for (int face = 0; face < nFacesHexa; ++face) {
>>    ReferenceTopologySet::getSubEntities<1,3>(hexahedron, face, faceIdx, n);
>>
>>    std::cout << "Face " << face << ":" << std::endl;
>>    std::cout << "(ReferenceTopologySet) "
>>              << "{ " << faceIdx[0] 
>>              << ", " << faceIdx[1] 
>>              << ", " << faceIdx[2] 
>>              << " }" << std::endl;
>>
>>    std::cout << "(ReferenceCube) "
>>              << "{ " << referenceCube.subentity(face, 1, 0, 3)
>>              << ", " << referenceCube.subentity(face, 1, 1, 3)
>>              << ", " << referenceCube.subentity(face, 1, 2, 3)
>>              << " }" << std::endl;
>>  }
>>} 
>>    
>>
>
>  
>
>>Test tetrahedra:
>>----------------
>>Face 0:
>>(ReferenceTopologySet) { 1, 3, 2 }
>>(ReferenceSimplex) { 1, 2, 3 }
>>Face 1:
>>(ReferenceTopologySet) { 0, 2, 3 }
>>(ReferenceSimplex) { 2, 0, 3 }
>>Face 2:
>>(ReferenceTopologySet) { 0, 3, 1 }
>>(ReferenceSimplex) { 0, 1, 3 }
>>Face 3:
>>(ReferenceTopologySet) { 0, 1, 2 }
>>(ReferenceSimplex) { 0, 1, 2 }
>>Test hexahedra:
>>---------------
>>Face 0:
>>(ReferenceTopologySet) { 0, 2, 4 }
>>(ReferenceCube) { 0, 2, 4 }
>>Face 1:
>>(ReferenceTopologySet) { 1, 3, 5 }
>>(ReferenceCube) { 1, 3, 5 }
>>Face 2:
>>(ReferenceTopologySet) { 0, 1, 4 }
>>(ReferenceCube) { 0, 1, 4 }
>>Face 3:
>>(ReferenceTopologySet) { 2, 3, 6 }
>>(ReferenceCube) { 2, 3, 6 }
>>Face 4:
>>(ReferenceTopologySet) { 0, 1, 2 }
>>(ReferenceCube) { 0, 1, 2 }
>>Face 5:
>>(ReferenceTopologySet) { 4, 5, 6 }
>>(ReferenceCube) { 4, 5, 6 }
>>    
>>
>
>  
>
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>>    
>>
>
>
>  
>



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