It provides a transition from elementary calculus to advanced courses in real and complex function theory and introduces the reader to some of the abstract thinking that pervades modern analysis.
Tom Apostol, who is still alive and ethusiastic about all kinds of mathematics, is well known for several textbooks on calculus at all levels. My first encounter was with his undergraduate text. I've had this book on my shelf for many years now and I regularly resort to it when I need clarification of points in analysis. Right now I'm using it as a reference for a study of what I call "Random Riemann Sums" wherein I am trying to combine my knowledge of Monte Carlo with analysis to better understand such things as sum distributions, partitions, bounded variation, etc. I find I can dip into Apostol's book more easily than other texts.
Probably the only mathematical text I have ever read cover-to-cover. A very good introduction to Analysis as long as you already have some maths background. Naturally as a pure maths text it is very dry, with some positively arid sections, even for one interested in learning the subject.
Written in 1957, it has stood the test of time. It is still very good. Good explanations and proofs. This is an advanced Calculus book. I have read and enjoyed Apostol’s two Calculus books. I have also enjoyed this advanced calculus book.