This classic book covers the solution of differential equations in science and engineering in such as way as to provide an introduction for novices before progressing toward increasingly more difficult problems. Problem sets make this book ideal for self-study or as a course text. The Method of Weighted Residuals and Variational Principles:* Describes variational principles, including how to find them and how to use them to construct error bounds and create stationary principles.* Illustrates how to use simple methods to find approximate solutions and how to use the finite element method for more complex problems.* Provides detailed information on error bounds.