This tutorial includes a neck-breaking review of some of the theory seen in class with an emphasis of the topics that are covered in the three numerical examples presented. One in linear mode, a second one in saturation and a third one in cut off. It is NOT a new video. It is the merging of four old videos from two years ago (when YouTube time limit was much smaller) into a more coherent unit. Less than half an hour in video, would be a 50 min tutorial session in a classroom.