The Book of Mathematics . Special sections. Elements of the Theory of Functions of Complex Variable and Operating Calculus. Probability Theory by H. A. Kondratieff is a unique work that opens the world of complex and fascinating mathematical science to the reader. If you have ever wondered how mathematics can explain the phenomena of the world around you, this book will be a real discovery for you. In his work, Kondratiev not only outlines theoretical aspects, but also immerses the reader in the practical application of mathematical concepts. It addresses important areas such as complex variable function theory, operational calculus, and probability theory, which are fundamental to many scientific and engineering disciplines. Each section of the book is riddled with deep reflections on how mathematics can be used to solve real-world problems, making the material particularly relevant to students, graduate students, and practitioners. The book will be of interest to a wide range of readers: from students of mathematical and engineering specialties to teachers and researchers seeking to deepen their knowledge in the field of higher mathematics. If you are passionate about mathematics, physics, computer science or even economics, then “Mathematics. Special sections" will become an indispensable tool for you. Kondratiev masterfully explains complex concepts, making them understandable, which is especially valuable for those who are just starting their way in studying these topics. The topics raised in the book cover not only theoretical aspects, but also practical applications. For example, in the section on the theory of functions of a complex variable, the author considers how these functions can be used to solve problems in physics and engineering, such as the analysis of electrical circuits and mechanical systems. Operational calculus, in turn, opens the door to understanding dynamical systems and their behavior, which is a key element in modern scientific research. Probability theory, as an important tool for the analysis of random processes, is of great importance in statistics, economics and even in sociology. Kondratiev's style is distinguished by clarity and logical presentation, which allows the reader to easily follow the author's thoughts. His approach to teaching mathematics is based on the principle of gradual complication of the material, which makes the book not only informative, but also convenient for self-study. Kondratiev is also known for his other works in which he explores various aspects of mathematics and its applications, which confirms his status as an expert in the field. This book not only expands the horizons of knowledge, but also inspires further study of mathematics. It will be an excellent addition to the library of anyone interested in science and committed to a deep understanding of mathematical principles. If you are looking for a high-quality mathematics textbook that will help you understand complex topics and apply the knowledge gained in practice, "Mathematics. Special Sections" is exactly what you need. Do not miss the opportunity to immerse yourself in the world of mathematics with H. A. Kondratieff and discover new horizons of knowledge that will help you not only in your studies, but also in your professional activities