Format: Full Color on White Paper, 7"x10" (256x178 mm), Paperback, 260 pages. Several other Colour and Black & White options are also avaliable. About the book: An excellent textbook established at several universities. Primarily written for students at technical universities, it is also a very useful handbook for engineers, PhD students and scientists. Now available in several forms at all continents. This textbook introduces the reader into various types of approximations of functions, which are defined either explicitly or by their values in the distinct set of points, as well as into the economisation of existing approximation formulas. Why the approximation of functions is so important? Simply, various functions (such as trigonometric functions and logarithms) cannot be calculated without approximation. Approximation formulas for some of these functions are already implemented in calculators and standard computer libraries, providing accuracy to all the bits in which a value is stored. High accuracy is usually not required and requires more numerical operations then necessary. Economised approximation formulas can provide the required accuracy with less numerical operations, and can make numerical algorithms faster, especially when such formulas are nested in loops. The other important use of approximation is in calculating functions that are defined by values at a chosen set of points. The book is divided into five chapters. The first chapter briefly explaines Maclaurin, Taylor or Padé expansion, principles of approximations with orthogonal series and principles of the least squares approximations. In the second chapter, various types of least squares polynomial approximations, particularly those using Legendre, Jacobi, Laguerre, Hermite, Zernike and Gram orthogonal polynomials are explained. The third chapter explains approximations with Fourier series, which are the base for developing approximations with Chebyshev polynomials (fourth chapter). Uniform approximation and further usage of Chebyshev polynomials in the almost uniform approximation, as well as in the economisation of the existing approximation formulas, are described in the fifth chapter. Practical application of the described approximation procedures is supported by 40 examples and 37 algorithms. In addition to its practical usage, the given text with 37 figures and 12 tables represents a valuable background for understanding, using, developing and applying various numerical methods, such as interpolation, numerical integration and solving partial differential equations, which are topics covered in the following volumes of the series Numerical Methods. Reviewed by: Prof. Maja Fosner, D.Sc., University of Maribor, Slovenia Prof. Damir Jelaska, D.Sc., University of Split, Croatia Prof. Valery Lysenko, D.Sc., Academic of the Russian Metrological Academy, Russian Research Institute for Metrological Service, Russia Prof. Iztok Potrc, D.Sc., University of Maribor. Slovenia Prof. Evgeny Pushkar, D.Sc., Member correspondent of the Russian Academy of Natural Sciences, Moscow State Industrial University, Russia Proof reading by: Jasenka Toplicanec, prof., Zagreb, Croatia

Paperback, color print on 70lb white paper. Other e- and printed color and b&w editions are or will be also available. * * * About the book: An excellent textbook established at several universities. Primarily written for students at technical universities, it is also a very useful handbook for engineers, PhD students and scientists. Now available at all continents. - - - This textbook introduces the reader into various types of approximations of functions, which are defined either explicitly or by their values in the distinct set of points, as well as into the economization of existing approximation formulas. - - - Why the approximation of functions is so important? Simply, various functions (such as trigonometric functions and logarithms) cannot be calculated without approximation. Approximation formulas for some of these functions are already implemented in calculators and standard computer libraries, providing accuracy to all the bits in which a value is stored. High accuracy is usually not required and requires more numerical operations then necessary. Economised approximation formulas can provide the required accuracy with less numerical operations, and can make numerical algorithms faster, especially when such formulas are nested in loops. The other important use of approximation is in calculating functions that are defined by values at a chosen set of points. - - - The book is divided into five chapters. The first chapter briefly explaines Maclaurin, Taylor or Pade expansion, principles of approximations with orthogonal series and principles of the least squares approximations. - - - In the second chapter, various types of least squares polynomial approximations, particularly those using Legendre, Jacobi, Laguerre, Hermite, Zernike and Gram orthogonal polynomials are explained. The third chapter explains approximations with Fourier series, which are the base for developing approximations with Chebyshev polynomials (fourth chapter). - - - Uniform approximation and further usage of Chebyshev polynomials in the almost uniform approximation, as well as in the economisation of the existing approximation formulas, are described in the fifth chapter. - - - Practical application of the described approximation procedures is supported by 40 examples and 37 algorithms. In addition to its practical usage, the given text with 37 figures and 12 tables represents a valuable background for understanding, using, developing and applying various numerical methods, such as interpolation, numerical integration and solving partial differential equations, which are topics covered in the following volumes of the series Numerical Methods. * * * Author: Boris Obsieger, D.Sc., professor at the University of Rijeka, Croatia. Head of Section for Machine Elements at the Faculty of Engineering in Rijeka. Holds lectures on Machine Elements Design, Robot Elements Design, Numerical Methods in Design and Boundary Element Method. Several invited lectures. President of CADAM Conferences. Main editor of international journal Advanced Engineering. Author of several books and a lot of scientific papers. * * * Reviewed by: Prof. Maja Fosner, D.Sc., University of Maribor, Slovenia; Prof. Damir Jelaska, D.Sc., University of Split, Croatia; Prof. Valery Lysenko, D.Sc., Academic of the Russian Metrological Academy, Russian Research Institute for Metrological Service; Prof. Iztok Potrc, D.Sc., University of Maribor. Slovenia; Prof. Evgeny Pushkar, D.Sc., Member correspondent of the Russian Academy of Natural Sciences, Moscow State Industrial University, Russia. * * * Proof reading by: Jasenka Toplicanec, prof., Rijeka, Croatia."

The book is written primarily for the students on technical universities, but also as a useful handbook for engineers and PhD students. It introduces reader into various types of approximations of functions, which are defined either explicitly or by their values in the distinct set of points, as well as into economisation of existing approximation formulas. Why the approximation of functions is so important? Simply because various functions cannot be calculated without approximation. Approximation formulas for some of these functions (such as trigonometric functions and logarithms) are already implemented in the calculators and standard computer libraries, providing the precision to all bits of memory in which a value is stored. So high precision is not usually required in the engineering practice, and use more numerical operations that is really necessary. Economised approximation formulas can provide required precision with less numerical operation, and can made numerical algorithms faster, especially when such formulas are used in nested loops. The other important use of approximation is in calculating functions that are defined by values in the chosen set of points, such as in solving integral equations (usually obtained from differential equations). The book is divided into five chapters. In the first chapter are briefly explained basic principles of approximations, i.e. approximations near the chosen point (by Maclaurin, Taylor or Padé expansion), principles of approximations with orthogonal series and principles of least squares approximations. In the second chapter, various types of least squares polynomial approximations, particularly those by using orthogonal polynomials such as Legendre, Jacobi, Laguerre, Hermite, Zernike and Gram polynomials are explained. Third chapter explains approximations with Fourier series, which are the base for developing approximations with Chebyshev polynomials (fourth chapter). Uniform approximation and further usage of Chebyshev polynomials in the almost uniform approximation, as well as in economisation of existing approximation formulas, are described in fifth chapter. Practical applications of described approximation procedures are supported by 35 algorithms and 40 examples. Besides its practical usage, the given text with 36 figures and 11 tables, partially in colour, represents a valuable background for understanding, developing and applying various numerical methods, such as interpolation, numerical integration and solving partial differential equations, which are topics in the further volumes of the series Numerical Methods.

This book presents numerical and other approximation techniques for solving various types of mathematical problems that cannot be solved analytically. In addition to well known methods, it contains some non-standard approximation techniques that are now formally collected as well as original methods developed by the author that do not appear in the literature. This book contains an extensive treatment of approximate solutions to various types of integral equations, a topic that is not often discussed in detail. There are detailed analyses of ordinary and partial differential equations and descriptions of methods for estimating the values of integrals that are presented in a level of detail that will suggest techniques that will be useful for developing methods for approximating solutions to problems outside of this text. The book is intended for researchers who must approximate solutions to problems that cannot be solved analytically. It is also appropriate for students taking courses in numerical approximation techniques.

for example, the so-called Lp approximation, the Bernstein approxima tion problem (approximation on the real line by certain entire functions), and the highly interesting studies of J. L. WALSH on approximation in the complex plane. I would like to extend sincere thanks to Professor L. COLLATZ for his many encouragements for the writing of this book. Thanks are equally due to Springer-Verlag for their ready agreement to my wishes, and for the excellent and competent composition of the book. In addition, I would like to thank Dr. W. KRABS, Dr. A. -G. MEYER and D. SCHWEDT for their very careful reading of the manuscript. Hamburg, March 1964 GUNTER MEINARDUS Preface to the English Edition This English edition was translated by Dr. LARRY SCHUMAKER, Mathematics Research Center, United States Army, The University of Wisconsin, Madison, from a supplemented version of the German edition. Apart from a number of minor additions and corrections and a few new proofs (e. g. , the new proof of JACKSON'S Theorem), it differs in detail from the first edition by the inclusion of a discussion of new work on comparison theorems in the case of so-called regular Haar systems (§ 6) and on Segment Approximation (§ 11). I want to thank the many readers who provided comments and helpful suggestions. My special thanks are due to the translator, to Springer-Verlag for their ready compliance with all my wishes, to Mr.

Everything is more simple than one thinks but at the same time more complex than one can understand Johann Wolfgang von Goethe To reach the point that is unknown to you, you must take the road that is unknown to you St. John of the Cross This is a book on the numerical approximation ofpartial differential equations (PDEs). Its scope is to provide a thorough illustration of numerical methods (especially those stemming from the variational formulation of PDEs), carry out their stability and convergence analysis, derive error bounds, and discuss the algorithmic aspects relative to their implementation. A sound balancing of theoretical analysis, description of algorithms and discussion of applications is our primary concern. Many kinds of problems are addressed: linear and nonlinear, steady and time-dependent, having either smooth or non-smooth solutions. Besides model equations, we consider a number of (initial-) boundary value problems of interest in several fields of applications. Part I is devoted to the description and analysis of general numerical methods for the discretization of partial differential equations. A comprehensive theory of Galerkin methods and its variants (Petrov Galerkin and generalized Galerkin), as wellas ofcollocationmethods, is devel oped for the spatial discretization. This theory is then specified to two numer ical subspace realizations of remarkable interest: the finite element method (conforming, non-conforming, mixed, hybrid) and the spectral method (Leg endre and Chebyshev expansion).

This book presents a unified theory of the Finite Element Method and the Boundary Element Method for a numerical solution of second order elliptic boundary value problems. This includes the solvability, stability, and error analysis as well as efficient methods to solve the resulting linear systems. Applications are the potential equation, the system of linear elastostatics and the Stokes system. While there are textbooks on the finite element method, this is one of the first books on Theory of Boundary Element Methods. It is suitable for self study and exercises are included.