Codes showing how to solve a boundary value problem by command lines
1. Construct geometry by geometrical matrix
2. Define boundary conditions (BCs) by a BC matrix
3. Match coefficients between the MATLAB elliptic solver and the PDE to be solved
4. Discretize PDE and BCs in the geometrical domain
5. Solve the BC problem and do post-processing
I don't have the PDE toolbox, so I can't run this to test it, but this is the kind of tutorial that you can read and learn from. It clearly explains the equations used, the boundary conditions, the geometry, and many points of interest. NICE job.