The mathematical tools used in signal analysis involve differential and difference equations, integral equations, matrix algebra and calculus, complex analysis and probability theory, and random processes. This book applies these tools to problems in various branches of physics like fluid dynamics, electromagnetism, and quantum theory. The book will be of use to research workers in signal processing, as well as to research workers in physics and applied mathematics. Partial differential equations have been introduced here as an additional tool in signal analysis since they are used to describe quantum, electromagnetic, and fluid dynamical phenomena, as well as Einstein's equations of gravitation. The book will be of use to signal processing experts who are interested in developing tools for the analysis of signals arising in real systems.