I followed up:

Great job! I want to use a mesh using quadrilaterals instead of triangles, how would I do that?

To create a mesh using quadrilateral elements in MATLAB, you can use the meshgrid function to generate a grid of points, and then use the delaunayTriangulation function to create a triangulation of the points. You can then extract the quadrilateral elements from the triangulation using the freeBoundary function.

Here is an example of how you can use these functions to create a mesh of quadrilateral elements:

% Define the region to be meshed xv = [0 1 1 0]; yv = [0 0 1 1];

% Generate a grid of points [X,Y] = meshgrid(xv,yv);

% Create a triangulation of the points TRI = delaunayTriangulation(X,Y);

% Extract the quadrilateral elements from the triangulation QB = TRI.freeBoundary;

% Plot the mesh triplot(TRI)

This will create a mesh of a square region with four nodes and one quadrilateral element. The QB matrix contains the indices of the nodes for each quadrilateral element.

You can also use the quadmesh function from the PDE Toolbox to create a mesh of quadrilateral elements. This function allows you to specify the element size and shape, and includes options for refining the mesh.

For more information on these functions and other tools for creating finite element meshes in MATLAB, you can refer to the documentation for the PDE Toolbox.