This book is aimed at providing a coherent, essentially self-contained, rigorous and comprehensive abstract theory of Feynman's operational calculus for noncommuting operators. Although it is inspired by Feynman's original heuristic suggestions and time-ordering rules in his seminal 1951 paper An operator calculus having applications in quantum electrodynamics, as will be made abundantly clear in the introduction (Chapter 1) and elsewhere in the text, the theory developed in this book also goes well beyond them in a number of directions which were not anticipated in Feynman's work. Hence, the second part of the main title of this book. The basic properties of the operational calculus are developed and certain algebraic and analytic properties of the operational calculus are explored. Also, the operational calculus will be seen to possess some pleasant stability properties. Furthermore, an evolution equation and a generalized integral equation obeyed by the operational calculus are discussed and connections with certain analytic Feynman integrals are noted. This volume is essentially self-contained and we only assume that the reader has a reasonable, graduate level, background in analysis, measure theory and functional analysis or operator theory. Much of the necessary remaining background is supplied in the text itself.

This book provides the most comprehensive mathematical treatment to date of the Feynman path integral and Feynman's operational calculus. It is accessible to mathematicians, mathematical physicists and theoretical physicists. Including new results and much material previously only available in the research literature, this book discusses both the mathematics and physics background that motivate the study of the Feynman path integral and Feynman's operational calculus, and also provides more detailed proofs of the central results.

Introduction to the Operational Calculus is a translation of "Einfuhrung in die Operatorenrechnung, Second Edition." This book deals with Heaviside's interpretation, on the Laplace integral, and on Jan Mikusinki's fundamental work "Operational Calculus." Throughout the book, basic algebraic concepts appear as aids to understanding some relevant points of the subject. An important field for research in analysis is asymptotic properties. This text also discusses examples to show the potentialities in applying operational calculus that run beyond ordinary differential equations with constant coefficients. In using operational calculus to solve more complicated problems than those of ordinary differential equations with constant coefficients, the concept of convergence assumes a significant role in the field of operators. This book also extends the Laplace transformation and applies it to non-transformable functions. This text also present three methods in which operational calculus can be modified and become useful in solving specific ranges of problems. These methods pertain to the finite Laplace transformation, to partial differential equations, and to the Volterra integral equations and ordinary differential equations with variable coefficients. This book can prove valuable for mathematicians, students, and professor of calculus and advanced mathematics.

Suitable for advanced undergraduates and graduate students, this brief monograph examines elementary and convergence theories of convolution quotients, differential equations involving operator functions, exponential functions of operators. Solutions. 1962 edition.

This text is about solving various types of equations using practical mathematical methods. Only the essentials of each topic are discussed. This is not about proving theorems, taking limits, or other matters important to mathematicians. "However, the emphasis should be somewhat more on how to do the mathematics quickly and easily, and what formulas are true, rather than the mathematicians' interest in methods of rigorous proof." Richard Feynman Concepts from Linear Algebra - the determinant, the finite matrix, the eigenvalue - are presented without the distractions of mathematical rigor. You learn solution methods that do not involve guesses. Methods you implement in a straightforward manner. The operational calculus can be traced back to Oliver Heaviside. Though many scientists preceded Heaviside in introducing operational methods, the systematic use of operational methods in physical problems was stimulated only by Heaviside's work. The methods he created are undoubtedly among the most important ever created. Heaviside was criticized for his lack of mathematical rigor. Yet his numerous mathematical and physical methods and results proved to be correct when mathematical rigor was incorporated. The Laplace Transform, a basis for a modern day operational calculus, is a straightforward technique for solving ordinary, partial differential, and, with a few complications, difference equations and a type of integral equation. On the other hand the Z transform solves difference equations without complications. And, Heaviside's differential operator D = d/dt augments the transform methods. The Laplace Transform transforms equations in one real variable domain, usually the time t domain, to a complex variable domain where the problem at hand is essentially solved. The inverse transform from the complex variable domain to the real variable domain completes the solution. Understanding the inverse transform requires knowledge of the theory of functions of complex variables. Our main interest in functions of a complex variable is integration, because integration of the complicated integrals of inverse transforms is amazingly simplified. The methods of the differential and integral calculus are extended to complex numbers and functions of complex variables. The results produce tremendous analytic methods. We show how ordinary differential equations. systems of ordinary differential equations, partial differential equations, and difference equations are readily solved by transform and/or differential operational methods. We show that each type of equation is solved in essentially the same way. We just define the Fourier Series, and show how to create Fourier series representing waveforms. Integral Equations - This is a hugh subject, which we limit to how the Laplace transform solves integral equations that include the convolution integral. Galois Finite Fields GF(2m) are not used to solve equations per se. They are used to implement functions such as error correcting codes, speech recognition, phase array antennas, and Doppler radar. Functions NOT implemented here.

In the end of the last century, Oliver Heaviside inaugurated an operational calculus in connection with his researches in electromagnetic theory. In his operational calculus, the operator of differentiation was denoted by the symbol "p". The explanation of this operator p as given by him was difficult to understand and to use, and the range of the valid ity of his calculus remains unclear still now, although it was widely noticed that his calculus gives correct results in general. In the 1930s, Gustav Doetsch and many other mathematicians began to strive for the mathematical foundation of Heaviside's operational calculus by virtue of the Laplace transform -pt e f(t)dt. ( However, the use of such integrals naturally confronts restrictions con cerning the growth behavior of the numerical function f(t) as t ~ ~. At about the midcentury, Jan Mikusinski invented the theory of con volution quotients, based upon the Titchmarsh convolution theorem: If f(t) and get) are continuous functions defined on [O,~) such that the convolution f~ f(t-u)g(u)du =0, then either f(t) =0 or get) =0 must hold. The convolution quotients include the operator of differentiation "s" and related operators. Mikusinski's operational calculus gives a satisfactory basis of Heaviside's operational calculus; it can be applied successfully to linear ordinary differential equations with constant coefficients as well as to the telegraph equation which includes both the wave and heat equa tions with constant coefficients.