This text is widely disparaged by underdgraduate students and with good reason. The writing is hasty, unclear, and the the author expects much of the reader. DO NOT BOTHER even cracking this book open unless you have had three semesters of calculus, a course on ordinary differential equations, and a course on real analysis. Results from all are used and expected to be known of the reader. The problems are very difficult. Luckily I had a professor who typed up detailed solutions to all the problems and made them available for borrowing and printing at the library. Go elsewhere. There are better books ( )