Fourier Analysis and Approximation of Functions

From the reviews: "The motivation for writing this extensive monograph of over 500 pages is to compile the basic and more current results in Fourier analysis that are particularly useful for solving certain approximation problems. … This is a very well written monograph with very rich content. It is an excellent reference source for researchers in approximation theory, and is also suitable for adoption as textbook for a graduate course … ." (Charles K. Chui, Mathematical Reviews, Issue 2005 k) "Part of the book is classical approximation theory and classical Fourier analysis (series and integrals in one and more variables) with the emphasis on approximation theory. … each chapter is concluded by a rather extensive section 'Further problems and theorems' which introduces extended or related results as exercises, often suggesting methods for the solutions, and a guide to the literature. … When used as a textbook, it will be a … source of inspiration for a researcher in approximation theory or harmonic analysis." (Adhemar Bultheel, Bulletin of the Belgian Mathematical Society, Vol. 15 (1), 2008).