Computational methods in power systems require significant inputs from diverse disciplines, such as data base structures, numerical analysis etc. Strategic decisions in sparsity exploitation and algorithm design influence large-scale simulation and high-speed computations. Selection of a programming paradigm shapes the design, its modularity and reusability. This has a far reaching effect on software maintenance. This book provides a unified object oriented (OO) treatment for power system analysis. Sparsity exploitation techniques in OO paradigm are emphasized to facilitate large scale and fast computing. Specific applications like large-scale load flow, short circuit analysis, state estimation and optimal power flow are discussed within this framework. A chapter on modelling and computational issues in power system dynamics is also included. Motivational examples and illustrations appear throughout the book. A library of C++ classes provided along with this book has classes for transmission lines, transformers and substation. A diskette with C++ programs is also included. It contains load flow, short circuit analysis and network topology processor applications. Power system data is provided and systems up to 150 buses can be studied.