meshToPet

[p,e,t] representation of FEMesh data

This page describes the legacy workflow. New features might not be compatible with the [p,e,t] representation of FEMesh data.

Syntax

[p,e,t] = meshToPet(mesh)

Description

[p,e,t] = meshToPet(mesh) extracts the legacy [p,e,t] mesh representation from a FEMesh Properties object.

Examples

Convert 2-D Mesh to [p,e,t] Form

This example shows how to convert a mesh in object form to [p,e,t] form.

Create a 2-D PDE geometry and incorporate it into a model object. View the geometry.

model = createpde(1);

R1 = [3,4,-1,1,1,-1,-.4,-.4,.4,.4]';
C1 = [1,.5,0,.2]';
% Pad C1 with zeros to enable concatenation with R1
C1 = [C1;zeros(length(R1)-length(C1),1)];
geom = [R1,C1];
ns = (char('R1','C1'))';
sf = 'R1-C1';
gd = decsg(geom,sf,ns);

geometryFromEdges(model,gd);
pdegplot(model,'EdgeLabels','on')
xlim([-1.1 1.1])
axis equal

Create a mesh for the geometry. View the mesh.

generateMesh(model);
pdemesh(model)
axis equal

Convert the mesh to [p,e,t] form.

[p,e,t] = meshToPet(model.Mesh);

View the sizes of the [p,e,t] matrices.

size(p)

ans = 1×2

     2   956

size(e)

ans = 1×2

     7   160

size(t)

ans = 1×2

     7   438

Input Arguments

mesh — Mesh object

Mesh property of a PDEModel object | output of generateMesh

Mesh object, specified as the Mesh property of a PDEModel object or as the output of generateMesh.

Example: model.Mesh

Output Arguments

p — Mesh points

2-by-Np matrix | 3-by-Np matrix

Mesh points, returned as a 2-by-Np matrix (2-D geometry) or a 3-by-Np matrix (3-D geometry). Np is the number of points (nodes) in the mesh. Column k of p consists of the x-coordinate of point k in p(1,k), the y-coordinate of point k in p(2,k), and, for 3-D, the z-coordinate of point k in p(3,k). For details, see Mesh Data.

e — Mesh edges

7-by-Ne matrix | mesh associativity object

Mesh edges, returned as a 7-by-Ne matrix (2-D), or a mesh associativity object (3-D). Ne is the number of edges in the mesh. An edge is a pair of points in p containing a boundary between subdomains, or containing an outer boundary. For details, see Mesh Data.

t — Mesh elements

4-by-Nt matrix | 7-by-Nt matrix | 5-by-Nt matrix | 11-by-Nt matrix

Mesh elements, returned as a 4-by-Nt matrix (2-D with linear elements), a 7-by-Nt matrix (2-D with quadratic elements), a 5-by-Nt matrix (3-D with linear elements), or an 11-by-Nt matrix (3-D with quadratic elements). Nt is the number of triangles or tetrahedra in the mesh.

The t(i,k), with i ranging from 1 through end - 1, contain indices to the corner points and possibly edge centers of element k. For details, see Mesh Data. The last row, t(end,k), contains the subdomain number of the element.

Tips

• Use meshToPet to obtain the p and t data for interpolation using pdeInterpolant.