This reprint contains a collection of research papers on spectral theory for differential and functional differential operators. Spectral theory plays a fundamental role in mathematics and has applications in various fields of science and engineering, e.g., in quantum and classical mechanics, geophysics, acoustics, and electronics. The collection includes recent studies on a variety of topics such as analytical and numerical methods for solving direct and inverse spectral problems, new developments in the theory of partial differential equations, pseudo-differential equations with fractional derivatives, asymptotical analysis for solutions of differential equations, spectral theory for abstract operators in Hilbert spaces, and inverse nodal problems.

This book is included in DOAB.