This second edition of Generalized Functions has been strengthened in many ways. The already extensive set of examples has been expanded. Since the publication of the first edition, there has been tremendous growth in the subject and I have attempted to incorporate some of these new concepts. Accordingly, almost all the chapters have been revised. The bibliography has been enlarged considerably. Some of the material has been reorganized. For example, Chapters 12 and 13 of the first edition have been consolidated into Chapter 12 of this edition by a judicious process of elimination and addition of the subject matter. The new Chapter 13 explains the interplay between the theories of moments, asymptotics, and singular perturbations. Similarly, some sections of Chapter 15 have been revised and included in earlier chapters to improve the logical flow of ideas. However, two sections are retained. The section dealing with the application of the probability theory has been revised, and I am thankful to Professor Z.L. Crvenkovic for her help. The new material included in this chapter pertains to the modern topics of periodic distributions and microlocal theory. I have demonstrated through various examples that familiarity with the generalized functions is very helpful for students in physical sciences and technology. For instance, the reader will realize from Chapter 6 how the generalized functions have revolutionized the Fourier analysis which is being used extensively in many fields of scientific activity.
The theory of generalized functions is a fundamental part of the toolkit of mathematicians, physicists, and theoretically inclined engineers. It has become increasingly clear that methods based on this theory, also known as the theory of distributions, not only help us to solve previously unsolved problems but also enalble us to recover known solutions in a very simple manner.
This book contains both the theory and applications of generalized functions with a significant feature being the quantity and variety of applications. Definitions and theorems are stated precisely, but rigor is minimized in favor of comprehension of techniques. Most of the material is easily accessible to senior undergraduate and graduate students in mathematical, physical and engineering sciences. The background required is limited to the standard courses in advanced calculus, ordinary and partial differential equations, and boundary value problems. The chapters that are suitable as a one semester course are furnished with sets of exercises.
This edition has been strengthened in many ways. Various new concepts have been added. Some of the new material has been reorganized to improve the logical flow of ideas. And the set of examples has been expanded considerably to make more of the ideas concrete in the reader's eye.
