This book is a watershed in the teaching of calculus and the essential mathematical methods required by undergraduate mathematicians, physicists and engineers.It will easily become the standard reference for methods courses , if it has not done so already.It starts right at the beginning with a refresher in basic calculus etc , and then proceeds to carefully develop multi-variable calculus, linear differential equations,complex variables, calculus of variations , tensors, representations, numerical analysis and prob&stats.What I really like about this book is the way general curvilinear coordinate transformations are explained at the end of the vector calculus section, to which you can refer when reading the chapter on tensors.I know of no other methods textbook which introduces tensors like this:many lesser texts (and that means all the rest) seem to feel that it is sufficient to teach people about raising indices, and give readers some vague hand-waving about coordinate transformations.This book is one to buy for this alone, as you will then have a firm grasp of why the tensor notation is like it is.Indeed, I would say that this book makes most other methods textbooks look the half-arsed disgrace that they are.Jacobians could be more carefully introduced, and the writing style can be a little Enid Blyton (phrases like 'one can consult the many excellent textbooks on such and such' can become rather monotonous), but apart from tiny niggles like this, this really is a truly comprehensive methods book, which really starts from the beginning and takes you well into the foothills of genuinely advanced techniques, and which you will keep through your professional life.An instant classic.