edge numbering in matrix dl and pde model

Hello, I have a question.

I obtain the matrix dl with the function decsg

[dl,bt] = decsg(gdm);

In dl the index column correspond to the different edges

so far so good.

I then need to divide the plate into different sections and build up the pde model :

geometryFromMesh(modelTwoDomain,msh.Nodes,msh.Elements,ElementIdToRegionId);

if i plot

pdegplot(dl,"Edgelabels","on","Facelabels","on","FaceAlpha",0.5)

pdegplot(modelTwoDomain,"Edgelabels","on","Facelabels","on","FaceAlpha",0.5)

I can see that the numbering of the edges in dl is different than the numbering of edges in modeltwodomain.

How can I find what is the numbering of edges in modeltwodomain?

Answer 1

[Maneet Kaur Bagga]

Hi Jorge,

As per my understanding to find the numbering of edges in the "modelTwoDomain" graph, "findEdge" function can be, it returns the numeric edge indices, "idxOut" for the edges specified by the source and the target node pairs s and t.

idxOut = findEdges(modelTwoDomain,s,t);

% Display the edge numbers
disp(idxOut);

Please refer to the following documentation for further information of the "findEdge" function.

https://www.mathworks.com/help/matlab/ref/graph.findedge.html

Hope this helps!

Thank You

Maneet Bagga

[Jorge Garcia Garcia]

Thanks Maneet

I have been able to locate the edges I need because of the coordinate in the matrix dl. Is there a similar matrix with coordinates for faces instead of edges?

[Maneet Kaur Bagga]

The "dl" matrix primarily contains information about the edges, vertices, and regions of the domain.

To obtain the coordinates of the faces, you may use the "pdegeom" function instead of "decsg" to create the geometry object and then use the "geometryFromEdges" function to generate the PDE model. The resulting model will have access to the face coordinates.

Documentation link:

https://www.mathworks.com/help/pde/ug/create-geometry-using-a-geometry-function.html

[Jorge Garcia Garcia]

thanks again! will check!