# pdesdp

(Not recommended) Indices of subset of mesh nodes belonging to specified faces of 2-D geometry

pdesdp is not recommended. Use findNodes instead.

## Description

example

s = pdesdp(p,e,t,FaceID) returns the indices of the nodes of the [p,e,t] mesh shared between two or more faces listed in FaceID.

example

[i,c] = pdesdp(p,e,t,FaceID) returns the indices of the nodes of the [p,e,t] mesh belonging strictly to faces FaceID as i. It also returns the indices of the nodes shared between FaceID and faces not listed in FaceID as c.

___ = pdesdp(p,e,t) uses any of the previous syntaxes, assuming that FaceID is a list of all faces of a 2-D geometry.

## Examples

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Find the indices of the mesh nodes belonging strictly to the specified faces and the indices of the nodes shared between faces.

Define two circles and a rectangle and place these in one matrix.

R1 = [3,4,-1,1,1,-1,0.5,0.5,-0.75,-0.75]';
C1 = [1,-0.5,-0.25,0.25]';
C2 = [1,0.5,-0.25,0.25]';
C1 = [C1;zeros(length(R1) - length(C1),1)];
C2 = [C2;zeros(length(R1) - length(C2),1)];
gd = [R1,C1,C2];

Create a set formula that adds the circles to the rectangle.

sf = 'R1+C1+C2';

Create and plot the geometry.

ns = char('R1','C1','C2');
ns = ns';
gd = decsg(gd,sf,ns);
pdegplot(gd,'FaceLabels','on')

Create a mesh.

[p,e,t] = initmesh(gd);

Plot the mesh with the node labels.

pdemesh(p,e,t,'NodeLabels','on')

Find the indices of the mesh nodes shared between faces 1 and 2.

s1 = pdesdp(p,e,t,[1 2])
s1 = 1×8

5     6     7     8    13    14    15    16

Find the indices of the mesh nodes shared between faces 2 and 3. Since these faces do not share any nodes, pdesdp returns an empty vector.

s2 = pdesdp(p,e,t,[2 3])
s2 =

1x0 empty double row vector

Find the nodes belonging strictly to face 2 and also the nodes shared between face 2 and other faces. Face 2 shares nodes only with face 1, therefore, vectors c and s1 consist of the same face IDs.

[i,c] = pdesdp(p,e,t,2)
i = 1×5

56    88    90    91    92

c = 1×8

5     6     7     8    13    14    15    16

## Input Arguments

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Mesh nodes, specified as a 2-by-Np matrix of nodes (points), where Np is the number of nodes in the mesh. For details on the mesh data representation, see initmesh.

Data Types: double

Mesh edges, specified as a 7-by-Ne matrix of edges, where Ne is the number of edges in the mesh. For details on the mesh data representation, see initmesh.

Data Types: double

Mesh elements, specified as a 4-by-Nt matrix of triangles, where Nt is the number of triangles in the mesh. For details on the mesh data representation, see initmesh.

Data Types: double

Face IDs, specified as a vector of integers.

Data Types: double

## Output Arguments

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Mesh nodes shared between two or more specified faces, returned as a row vector of positive integers representing the indices of the nodes.

Mesh nodes belonging only to specified faces, returned as a row vector of positive integers representing the indices of the nodes.

Mesh nodes shared between specified and other faces, returned as a row vector of positive integers representing the indices of the nodes.

## Version History

Introduced before R2006a

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