Dear Egor, 

Since Nedelec space is strictly included into the P3 space, I think, you have 
first to decide the kind of operation you want to do : interpolation or 
projection. 
The interpolation can be done has you described (you can interpolate the P3 fem 
on the finite element node of the Nedelec FEM, the problem being to perform the 
scalar product with the right edges). 

Concerning the L2 projection, it consists in the assembly of the mass matrix 
for the Nedelec FEM and the corresponding RHS (Nedelec x P3), then solving the 
linear system. 

Best regards, 

Yves 




De: "Egor Vtorushin" <[email protected]> 
À: "getfem-users" <[email protected]> 
Envoyé: Vendredi 17 Septembre 2021 10:53:30 
Objet: E field conversation from Nodal to Edge 

Dear Yves, 
Do you have any hints on how to make a conversation from Nodal mesh fem to Edge 
mesh fem on the same mesh? 
Let we have ONESIMPLMESH that is 3D mesh with only one 4 vertex simplex(for 
sake of simplicity) 
There are two mesh fems 

mfNODAL = gf.MeshFem(ONESIMPLMESH,3) 
mfNODAL .set_fem(gf.Fem("FEM_PK(3,1)")) 

and 

mfEDGE = gf.MeshFem( ONESIMPLMESH ,3) 
mfEDGE.set_fem(gf.Fem("FEM_NEDELEC(3)")) 

Assume we have some three component electric(or else) field defined(evaluated 
or calculated) in mfNODAL nodes 
In our case it is length of 12 vector - 3 field components in 4 nodes 
Now i want to translate this field to mfEDGE mesh fem and gets length of 6 
vector- values defined on each edge of the one simplex 
I know that it works some basic algebra like for 0-th component of mfEDGE field 
E 
E0 = numpy.dot((N0+N1),(PTS[1]-PTS[0]))/2 
here (E0 stands for edge and N0,N1 stands for nodal) 
But I am interested if there is some way to implement it via generic assembly 
procedures? 
Regards, Egor Vtorushin 

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