Nonlinear Approximation Theory

Nonlinear Approximation Theory PDF Author: Dietrich Braess
Publisher: Springer Science & Business Media
ISBN: 3642616097
Category : Mathematics
Languages : en
Pages : 305

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Book Description
The first investigations of nonlinear approximation problems were made by P.L. Chebyshev in the last century, and the entire theory of uniform approxima tion is strongly connected with his name. By making use of his ideas, the theories of best uniform approximation by rational functions and by polynomials were developed over the years in an almost unified framework. The difference between linear and rational approximation and its implications first became apparent in the 1960's. At roughly the same time other approaches to nonlinear approximation were also developed. The use of new tools, such as nonlinear functional analysis and topological methods, showed that linearization is not sufficient for a complete treatment of nonlinear families. In particular, the application of global analysis and the consideration of flows on the family of approximating functions intro duced ideas which were previously unknown in approximation theory. These were and still are important in many branches of analysis. On the other hand, methods developed for nonlinear approximation prob lems can often be successfully applied to problems which belong to or arise from linear approximation. An important example is the solution of moment problems via rational approximation. Best quadrature formulae or the search for best linear spaces often leads to the consideration of spline functions with free nodes. The most famous problem of this kind, namely best interpolation by poly nomials, is treated in the appendix of this book.

Nonlinear Approximation Theory

Nonlinear Approximation Theory PDF Author: Dietrich Braess
Publisher: Springer Science & Business Media
ISBN: 3642616097
Category : Mathematics
Languages : en
Pages : 305

Get Book

Book Description
The first investigations of nonlinear approximation problems were made by P.L. Chebyshev in the last century, and the entire theory of uniform approxima tion is strongly connected with his name. By making use of his ideas, the theories of best uniform approximation by rational functions and by polynomials were developed over the years in an almost unified framework. The difference between linear and rational approximation and its implications first became apparent in the 1960's. At roughly the same time other approaches to nonlinear approximation were also developed. The use of new tools, such as nonlinear functional analysis and topological methods, showed that linearization is not sufficient for a complete treatment of nonlinear families. In particular, the application of global analysis and the consideration of flows on the family of approximating functions intro duced ideas which were previously unknown in approximation theory. These were and still are important in many branches of analysis. On the other hand, methods developed for nonlinear approximation prob lems can often be successfully applied to problems which belong to or arise from linear approximation. An important example is the solution of moment problems via rational approximation. Best quadrature formulae or the search for best linear spaces often leads to the consideration of spline functions with free nodes. The most famous problem of this kind, namely best interpolation by poly nomials, is treated in the appendix of this book.

Nonlinear Analysis

Nonlinear Analysis PDF Author: Qamrul Hasan Ansari
Publisher: Springer
ISBN: 8132218833
Category : Mathematics
Languages : en
Pages : 362

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Book Description
Many of our daily-life problems can be written in the form of an optimization problem. Therefore, solution methods are needed to solve such problems. Due to the complexity of the problems, it is not always easy to find the exact solution. However, approximate solutions can be found. The theory of the best approximation is applicable in a variety of problems arising in nonlinear functional analysis and optimization. This book highlights interesting aspects of nonlinear analysis and optimization together with many applications in the areas of physical and social sciences including engineering. It is immensely helpful for young graduates and researchers who are pursuing research in this field, as it provides abundant research resources for researchers and post-doctoral fellows. This will be a valuable addition to the library of anyone who works in the field of applied mathematics, economics and engineering.

Approximation Theory and Approximation Practice, Extended Edition

Approximation Theory and Approximation Practice, Extended Edition PDF Author: Lloyd N. Trefethen
Publisher: SIAM
ISBN: 1611975948
Category : Mathematics
Languages : en
Pages : 375

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Book Description
This is a textbook on classical polynomial and rational approximation theory for the twenty-first century. Aimed at advanced undergraduates and graduate students across all of applied mathematics, it uses MATLAB to teach the field’s most important ideas and results. Approximation Theory and Approximation Practice, Extended Edition differs fundamentally from other works on approximation theory in a number of ways: its emphasis is on topics close to numerical algorithms; concepts are illustrated with Chebfun; and each chapter is a PUBLISHable MATLAB M-file, available online. The book centers on theorems and methods for analytic functions, which appear so often in applications, rather than on functions at the edge of discontinuity with their seductive theoretical challenges. Original sources are cited rather than textbooks, and each item in the bibliography is accompanied by an editorial comment. In addition, each chapter has a collection of exercises, which span a wide range from mathematical theory to Chebfun-based numerical experimentation. This textbook is appropriate for advanced undergraduate or graduate students who have an understanding of numerical analysis and complex analysis. It is also appropriate for seasoned mathematicians who use MATLAB.

Methods of Approximation Theory in Complex Analysis and Mathematical Physics

Methods of Approximation Theory in Complex Analysis and Mathematical Physics PDF Author: Andrei A. Gonchar
Publisher: Springer
ISBN: 3540477926
Category : Mathematics
Languages : en
Pages : 225

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Book Description
The book incorporates research papers and surveys written by participants ofan International Scientific Programme on Approximation Theory jointly supervised by Institute for Constructive Mathematics of University of South Florida at Tampa, USA and the Euler International Mathematical Instituteat St. Petersburg, Russia. The aim of the Programme was to present new developments in Constructive Approximation Theory. The topics of the papers are: asymptotic behaviour of orthogonal polynomials, rational approximation of classical functions, quadrature formulas, theory of n-widths, nonlinear approximation in Hardy algebras,numerical results on best polynomial approximations, wavelet analysis. FROM THE CONTENTS: E.A. Rakhmanov: Strong asymptotics for orthogonal polynomials associated with exponential weights on R.- A.L. Levin, E.B. Saff: Exact Convergence Rates for Best Lp Rational Approximation to the Signum Function and for Optimal Quadrature in Hp.- H. Stahl: Uniform Rational Approximation of x .- M. Rahman, S.K. Suslov: Classical Biorthogonal Rational Functions.- V.P. Havin, A. Presa Sague: Approximation properties of harmonic vector fields and differential forms.- O.G. Parfenov: Extremal problems for Blaschke products and N-widths.- A.J. Carpenter, R.S. Varga: Some Numerical Results on Best Uniform Polynomial Approximation of x on 0,1 .- J.S. Geronimo: Polynomials Orthogonal on the Unit Circle with Random Recurrence Coefficients.- S. Khrushchev: Parameters of orthogonal polynomials.- V.N. Temlyakov: The universality of the Fibonacci cubature formulas.

Approximation Theory and Applications

Approximation Theory and Applications PDF Author: Zvi Ziegler
Publisher:
ISBN:
Category : Mathematics
Languages : en
Pages : 384

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Book Description
Construction of elements of the relative chebyshev center. The numerical claculation of spline approximations on a binfinite. Global analysis in nonlinear approximation and its application to exponential approximation. Global analysis in nonlinear approximation and its application to exponential approximation. Simultaneous approximation and restricted chebyshev centers in function spaces. Quelques proprietes D'Une family D'operateurs positfs sur des espaces de functions relles definies presque partout sur ... Bell-Shaped basis functions for surface fitting. The n-Widhts of sets of analytic functions. Admissibility of quadrature formulas with random nodes. Convergence for operators of hyperbolic type. Explicit ... - extensions of functions of two variebles in a strip between two curves, or in a corner in IR ... Taylor interpolation of order n at the vertices of a triangle. Applications for hermite interpolation and finite elements. Jacobi projections. Oscillating monosplines of least uniform norm. Some applications and drawbacks of padé approximants. From dirac distributions to multivariate representation formulas. A new iterative method for the solution of systems nonlinear equations. Polynomials and rational functions. Quadrature formulae based on shape preserving interpolation. Optimal recovery among the polynomials. On cardinal spline interpolants. Approximation by lacunary polynomials: A converse theorem. An interpolatory rational approximation. Design problems for optimal surface interpolation. Open problems.

Fixed Point Theory and Best Approximation: The KKM-map Principle

Fixed Point Theory and Best Approximation: The KKM-map Principle PDF Author: S.P. Singh
Publisher: Springer Science & Business Media
ISBN: 9401588228
Category : Mathematics
Languages : en
Pages : 231

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Book Description
The aim of this volume is to make available to a large audience recent material in nonlinear functional analysis that has not been covered in book format before. Here, several topics of current and growing interest are systematically presented, such as fixed point theory, best approximation, the KKM-map principle, and results related to optimization theory, variational inequalities and complementarity problems. Illustrations of suitable applications are given, the links between results in various fields of research are highlighted, and an up-to-date bibliography is included to assist readers in further studies. Audience: This book will be of interest to graduate students, researchers and applied mathematicians working in nonlinear functional analysis, operator theory, approximations and expansions, convex sets and related geometric topics and game theory.

Linear, Time-varying Approximations to Nonlinear Dynamical Systems

Linear, Time-varying Approximations to Nonlinear Dynamical Systems PDF Author: Maria Tomas-Rodriguez
Publisher: Springer Science & Business Media
ISBN: 184996100X
Category : Mathematics
Languages : en
Pages : 303

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Book Description
Linear, Time-varying Approximations to Nonlinear Dynamical Systems introduces a new technique for analysing and controlling nonlinear systems. This method is general and requires only very mild conditions on the system nonlinearities, setting it apart from other techniques such as those – well-known – based on differential geometry. The authors cover many aspects of nonlinear systems including stability theory, control design and extensions to distributed parameter systems. Many of the classical and modern control design methods which can be applied to linear, time-varying systems can be extended to nonlinear systems by this technique. The implementation of the control is therefore simple and can be done with well-established classical methods. Many aspects of nonlinear systems, such as spectral theory which is important for the generalisation of frequency domain methods, can be approached by this method.

Progress in Approximation Theory

Progress in Approximation Theory PDF Author: A.A. Gonchar
Publisher: Springer Science & Business Media
ISBN: 1461229669
Category : Mathematics
Languages : en
Pages : 463

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Book Description
Designed to give a contemporary international survey of research activities in approximation theory and special functions, this book brings together the work of approximation theorists from North America, Western Europe, Asia, Russia, the Ukraine, and several other former Soviet countries. Contents include: results dealing with q-hypergeometric functions, differencehypergeometric functions and basic hypergeometric series with Schur function argument; the theory of orthogonal polynomials and expansions, including generalizations of Szegö type asymptotics and connections with Jacobi matrices; the convergence theory for Padé and Hermite-Padé approximants, with emphasis on techniques from potential theory; material on wavelets and fractals and their relationship to invariant measures and nonlinear approximation; generalizations of de Brange's in equality for univalent functions in a quasi-orthogonal Hilbert space setting; applications of results concerning approximation by entire functions and the problem of analytic continuation; and other topics.

Nonlinear Integral Operators and Applications

Nonlinear Integral Operators and Applications PDF Author: Carlo Bardaro
Publisher: Walter de Gruyter
ISBN: 3110199270
Category : Mathematics
Languages : en
Pages : 214

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Book Description
In 1903 Fredholm published his famous paper on integral equations. Since then linear integral operators have become an important tool in many areas, including the theory of Fourier series and Fourier integrals, approximation theory and summability theory, and the theory of integral and differential equations. As regards the latter, applications were soon extended beyond linear operators. In approximation theory, however, applications were limited to linear operators mainly by the fact that the notion of singularity of an integral operator was closely connected with its linearity. This book represents the first attempt at a comprehensive treatment of approximation theory by means of nonlinear integral operators in function spaces. In particular, the fundamental notions of approximate identity for kernels of nonlinear operators and a general concept of modulus of continuity are developed in order to obtain consistent approximation results. Applications to nonlinear summability, nonlinear integral equations and nonlinear sampling theory are given. In particular, the study of nonlinear sampling operators is important since the results permit the reconstruction of several classes of signals. In a wider context, the material of this book represents a starting point for new areas of research in nonlinear analysis. For this reason the text is written in a style accessible not only to researchers but to advanced students as well.

Nonlinear Potential Theory and Weighted Sobolev Spaces

Nonlinear Potential Theory and Weighted Sobolev Spaces PDF Author: Bengt O. Turesson
Publisher: Springer
ISBN: 3540451684
Category : Mathematics
Languages : en
Pages : 188

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Book Description
The book systematically develops the nonlinear potential theory connected with the weighted Sobolev spaces, where the weight usually belongs to Muckenhoupt's class of Ap weights. These spaces occur as solutions spaces for degenerate elliptic partial differential equations. The Sobolev space theory covers results concerning approximation, extension, and interpolation, Sobolev and Poincaré inequalities, Maz'ya type embedding theorems, and isoperimetric inequalities. In the chapter devoted to potential theory, several weighted capacities are investigated. Moreover, "Kellogg lemmas" are established for various concepts of thinness. Applications of potential theory to weighted Sobolev spaces include quasi continuity of Sobolev functions, Poincaré inequalities, and spectral synthesis theorems.