F. G. Friedlander – författare

The large number of text books on the theory of sound deal principally with periodic disturbances such as harmonic wave trains and standing waves and give scant attention to aperiodic disturbances with clearly defined fronts, conveniently called sound pulses. This monograph attempts to fill this gap by providing an up-to-date description of the theory of sound pulses and its developments. The treatment is based on the thoery of linear partial differential equations of hyperbolic type - a method which is frequently simpler and more effective than the commoner one of resolving the pulse into harmonic components by Fourier analysis; this is especially true of any treatment of pulse fronts as wave fronts in the sense of geometrical optics. The individual chapters deal with the equations of motion, wave fronts and characteristics, geometrical acoustics and their application to reflection problems and the diffraction of a pulse by a wedge, circular cylinder, sphere and other objects. The book will also be of interest to readers concerned with other aspects of wave propagation, such as electromagnetic waves.

This book was originally published in 1975. In Einstein's General Theory of Relativity the effects of gravitation are represented by the curvature of space-time. Physical processes occurring in the presence of gravitation must then be treated mathematically in terms of their behaviour in a curved space-time. One of the most basic of these processes is wave propagation, and this book gives a rigourous discussion of the local effects of curvature on the behaviour of waves. In the course of this discussion many techniques are developed which are also needed for a study of more general problems, in which the gravitational field itself plays a dynamical role. Although much of the book deals with four-dimensional space-time, the n-dimensional case is also treated, more briefly. The subject-matter is also of interest in other branches of mathematical physics and, as a fresh account of the classical work of Hadamard and M. Riesz, in the theory of partial differential equations.

The theory of distributions is an extension of classical analysis which has acquired a particular importance in the field of linear partial differential equations, as well as having many other applications, for example in harmonic analysis. Underlying it is the theory of topological vector spaces, but it is possible to give a systematic presentation without presupposing a knowledge, or using more than a bare minimum, of this. This book, first published in 1999, adopts this course and is based on graduate lectures given over a number of years. The prerequisites are few, but a reasonable degree of mathematical maturity is expected of the reader, as the treatment is rigorous throughout. From the outset the theory is developed in several variables, unlike most elementary texts; it is taken as far as such important topics as Schwartz kernels, the Paley-Wiener-Schwartz theorem and Sobolev spaces.

The theory of distributions is an extension of classical analysis which has acquired a particular importance in the field of linear partial differential equations, as well as having many other applications, for example in harmonic analysis. Underlying it is the theory of topological vector spaces, but it is possible to give a systematic presentation without presupposing a knowledge, or using more than a bare minimum, of this. This book, first published in 1999, adopts this course and is based on graduate lectures given over a number of years. The prerequisites are few, but a reasonable degree of mathematical maturity is expected of the reader, as the treatment is rigorous throughout. From the outset the theory is developed in several variables, unlike most elementary texts; it is taken as far as such important topics as Schwartz kernels, the Paley-Wiener-Schwartz theorem and Sobolev spaces.