The present book is a collection of special courses in high mathematics intended for advanced engineering students, physicists and applied scientists working in academic and industrial research. It stems from lectures given by the author for a number of years and can be used both for studying under the guidance of a teacher and for self-instruction. The reader is supposed to be familiar with fundamentals of high mathematics (for this purpose we can recommend [107]). In the presentation of the material primary emphasis has been placed on the practical significance of mathematical notions and their application. This is a course of applied mathematics and not a theorem-proving book, and therefore intuitive methods take precedence over logical ones.