This text covers numerical analysis, applied mathematics, and solution procedures for differential equations. It should be of help to nonmathematicians interested in applying these methods and techniques. The problems are intended as links between theory and application, and provide a foundation. Originally published in 1961, this "Classics" edition describes a large number of techniques still useful today. Although the primary focus is on the analytical theory, concrete cases are cited to forge the link between theory and practice. Considerable manipulative skill in the practice of differential equations is to be developed by solving the 350 problems in the text. The problems are intended as stimulating corollaries linking theory with application and providing the reader with the foundation for tackling more difficult problems.