The text concentrates on solving Laplace equation applying three dimensional finite difference in Cartesian system with emphasis in MATLAB, a popular computer simulation platform for technical problems. Had we had close form solutions to all 3D problems, we would not have thought about the FD candidly owing to the complexity involved and higher dimensionality of electromagnetics, realistic systems of which are 3D to a large extent. Although laser sharp focus is on the solution, application of the 3D FD is well demonstrated to electromagnetic systems. Analyzing convenience by 3D FD reveals one...