Book excerpt: Circuit Simulation Methods and Algorithms provides a step-by-step theoretical consideration of methods, techniques, and algorithms in an easy-to-understand format. Many illustrations explain more difficult problems and present instructive circuits. The book works on three levels: The simulator-user level for practitioners and students who want to better understand circuit simulators. The basic theoretical level, with examples, dedicated to students and beginning researchers. The thorough level for deep insight into circuit simulation based on computer experiments using PSPICE and OPTIMA. Only basic mathematical knowledge, such as matrix algebra, derivatives, and integrals, is presumed.