To illustrate the application of the material，problems are given at the end of some chapters. Most of the problems can be solved by using a pocket calculator，although some of them should be programmed for a digital computer.The problems are not meant for testing the student reader，but are included primarily for extending and enriching the learning process. They suggest alternative techniques and present additional material. At times，in my attempt to give a hint for the problem solution，I almost disclose the full answer. In such cases，arriving at the correct answer is not the main objective;the reader should focus on the message that the problem is designed to convey.
　　This book carries the description of the numerical method to a point where the reader could begin to write a computer program. Indeed，the reader should be able to construct computer programs that generate the kind of results presented in the final chapter of the book. A range of computer programs of varying generality can be designed depending upon the nature of the problems to be solved. Many readers might have found it helpful if a representative computer program were included in tlus book. I did consider the possibility. However，the task of providing a reasonably general computer program，its detailed description，and several examples of its use seemed so formidable that it would have considerably delayed the publication of this book. For the time being，I have included a section on the preparation and testing of a computer program（Section 7.4），where many useful procedures and practices gathered through experience are described.