The book contains a detailed account of the first non-Newtonian calculus. In this system, the exponential functions play the role that the linear functions play in the classical calculus of Newton and Leibniz. This nonlinear system provides mathematical tools for use in science, engineering, and mathematics. It appears to have considerable potential for use as an alternative to the classical calculus. It may well be that this non-Newtonian calculus can be used to define new concepts, to yield new or simpler laws, or to formulate or solve problems.