This book tells the intriguing and entertaining story of asymptotic analysis through a series of well-chosen examples. Some of the examples are contrived to illustrate a method, but most are interesting in themselves. Several problems are given more than one solution; these include Stirling’s formula and the problem of the iterated sine (that is, the asymptotic behavior of the sequence defined by xn+1 = sin xn). The examples are organized into chapters by the primary technique used. It is difficult to state very general theorems or methods in asymptotics; instead the book teaches you methods for particular problems that can be adapted to other problems.
The first two-thirds of the book deals with direct asymptotics, where we have an explicit but not easy-to-use expression for the function of interest and we seek a convenient approximate form; Stirling’s formula for the gamma function is a typical example. The rest of the book deals with problems where we lack the explicit form but have other information such as a functional equation or average asymptotic information; these problems include Tauberian theorems, differential equations, and recursions.
It is a concise book, and despite covering a wide variety of topics still omits several important ones: there is almost nothing on analytic number theory, a subject that is the source of many delicate and important asymptotic problems; asymptotic series occur in several spots but are never used for numerical work; and the asymptotics of differential equations get one chapter but the subject is so broad that it can only be sketched here.
The book is clearly written and is always easy to follow, even when going through intricate reasoning. The book doesn’t use the terminology “bootstrapping,” but its description of this technique is especially good (in bootstrapping we we start with a very crude estimate and use this to develop several progressively more precise estimates).
Allen Stenger is a math hobbyist and retired software developer. He is webmaster and newsletter editor for the MAA Southwestern Section and is an editor of the Missouri Journal of Mathematical Sciences. His mathematical interests are number theory and classical analysis. He volunteers in his spare time at MathNerds.org, a math help site that fosters inquiry learning.