Of the various interval-based software packages that are available, we chose INTLAB for several reasons. It is fully integrated into the interactive, programmable, and highly popular MATLAB system. It is carefully written, with all basic interval computations represented. Finally, both MATLAB and INTLAB code can be written in a fashion that is clear and easy to debug. We wish to cordially thank George Corliss, Andreas Frommer, and Siegfried Rump, as well as the anonymous reviewers, for their many constructive comments. We owe Siegfried Rump additional thanks for developing INTLAB and granting us permission to use it in this book.