Bruce R. Kusse and Erik A . Westwig Mathematical Physics Applied Mathematics for Scientists and Engineers 2nd Edition WILEY- VCH WILEY-VCH Verlag GmbH & Co. KGaA This Page Intentionally Left Blank Bruce R. Kusse and ErikA. Westwig Mathematical Physics Related Titles Vaughn, M. T. Introduction to Mathematical Physics 2006. Approx. 650 pages with 50 figures. Softcover ISBN 3-527-40627-1 Lambourne, R., Tinker, M. Basic Mathematics for the Physical Sciences 2000.688 pages. Softcover ISBN 0-47 1-85207-4 Tinker, M., Lambourne, R. Further Mathematics for the Physical Sciences 2000.744 pages. Softcover ISBN 0-471-86723-3 Courant, R., Hilbert, D. Methods of Mathematical Physics Volume 1 1989. 575 pages with 27 figures. Softcover ISBN 0-47 1-50447-5 Volume 2 1989. 852 pages with 61 figures. Softcover ISBN 0-471-50439-4 Trigg, G. L. (ed.) Mathematical Tools for Physicists 2005.686 pages with 98 figures and 29 tables. Hardcover ISBN 3-527-40548-8 Bruce R. Kusse and Erik A. Westwig Mathematical Physics Applied Mathematics for Scientists and Engineers 2nd Edition WILEY- VCH WILEY-VCH Verlag GmbH & Co. KGaA The Authors All books published by Wiley-VCH are carefully produced. Nevertheless, authors, editors, and Bruce R. Kusse publisher do not warrant the information contained in College of Engineering these books, including this book, to be free of errors. Cornell University Readers are advised to keep in mind that statements, Ithaca, NY data, illustrations, procedural details or other items This book is the result of a sequence of two courses given in the School of Applied and Engineering Physics at Cornell University. The intent of these courses has been to cover a number of intermediate and advanced topics in applied mathematics that are needed by science and engineering majors. The courses were originally designed for junior level undergraduates enrolled in Applied Physics, but over the years they have attracted students from the other engineering departments, as well as physics, chemistry, astronomy and biophysics students. Course enrollment has also expanded to include freshman and sophomores with advanced placement and graduate students whose math background has needed some reinforcement. While teaching this course, we discovered a gap in the available textbooks we felt appropriate for Applied Physics undergraduates. There are many good introductory calculus books. One such example is Calculus andAnalytic Geometry by Thomas and Finney, which we consider to be a prerequisite for our book. There are also many good textbooks covering advanced topics in mathematical physics such as Mathematical Methods for Physicists by Arfken. Unfortunately, these advanced books are generally aimed at graduate students and do not work well for junior level undergraduates. It appeared that there was no intermediate book which could help the typical student make the transition between these two levels. Our goal was to create a book to fill this need. The material we cover includes intermediate topics in linear algebra, tensors, curvilinearc oordinate systems, complex variables, Fourier series, Fourier and Laplace transforms, differential equations, Dirac delta-functions, and solutions to Laplace’s equation. In addition, we introduce the more advanced topics of contravariance and covariance in nonorthogonal systems, multi-valued complex functions described with branch cuts and Riemann sheets, the method of steepest descent, and group theory. These topics are presented in a unique way, with a generous use of illustrations and V vi PREFACE graphs and an informal writing style, so that students at the junior level can grasp and understand them. Throughout the text we attempt to strike a healthy balance between mathematical completeness and readability by keeping the number of formal proofs and theorems to a minimum. Applications for solving real, physical problems are stressed. There are many examples throughout the text and exercises for the students at the end of each chapter. Unlike many text books that cover these topics, we have used an organization that is fundamentally pedagogical. We consider the book to be primarily a teaching tool, although we have attempted to also make it acceptable as a reference. Consistent with this intent, the chapters are arranged as they have been taught in our two course sequence, rather than by topic. Consequently, you will find a chapter on tensors and a chapter on complex variables in the first half of the book and two more chapters, covering more advanced details of these same topics, in the second half. In our first semester course, we cover chapters one through nine, which we consider more important for the early part of the undergraduate curriculum. The last six chapters are taught in the second semester and cover the more advanced material. We would like to thank the many Cornell students who have taken the AEP 3211322 course sequence for their assistance in finding errors in the text, examples, and exercises. E.A.W. would like to thank Ralph Westwig for his research help and the loan of many useful books. He is also indebted to his wife Karen and their son John for their infinite patience. BRUCER . KUSSE ERIKA . WESTWIG Ithaca, New York CONTENTS 1 A Review of Vector and Matrix Algebra Using SubscriptlSummation Conventions 1 1.1 Notation, I 1.2 Vector Operations, 5 2 Differential and Integral Operations on Vector and Scalar Fields 18 2.1 Plotting Scalar and Vector Fields, 18 2.2 Integral Operators, 20 2.3 Differential Operations, 23 2.4 Integral Definitions of the Differential Operators, 34 2.5 TheTheorems, 35 3 Curvilinear Coordinate Systems 44 3.1 The Position Vector, 44 3.2 The Cylindrical System, 45 3.3 The Spherical System, 48 3.4 General Curvilinear Systems, 49 3.5 The Gradient, Divergence, and Curl in Cylindrical and Spherical Systems, 58