The advent of the computer has drastically changed and widened the field of applied mathematics. The "graphical and numerical methods" taught some thirty years ago rather incoherently in small courses have given way to a broad and complex treatment from very different view-points, and the struggle for ever-in-creasing accuracy has brought forth a considerable diver sification according to the different fields of application. The mathematical theorist, striving for general theorems and unified methods, might regret this development but as long as the demands of practical problems surpass what...