Theory of Functions by Joseph Fels Ritt is a comprehensive reference book on the theory of functions. The book covers a wide range of topics, including complex variables, real variables, and the theory of functions of a real variable. It also includes discussions on algebraic and transcendental functions, differential equations, and the theory of functions of several variables. The book is written in a clear and concise style, making it accessible to both students and professionals in the field. It contains numerous examples and exercises to aid in understanding the material. Overall, Theory of Functions is an essential resource for anyone interested in the theory of functions.This scarce antiquarian book is a facsimile reprint of the old original and may contain some imperfections such as library marks and notations. Because we believe this work is culturally important, we have made it available as part of our commitment for protecting, preserving, and promoting the world's literature in affordable, high quality, modern editions, that are true to their original work.