That warms my heart as an open-source enthusiast, but it's slightly strange, for a couple of reasons.
Like Garrett's text, this one appears to have been done in La Te X, is licensed under the GPL, and appears to suffer from the same legal problems, because it's not available in source form.
The book is well written, and seems to have been well designed for practical classroom use.
The author may consider it a trivial task to set up a spreadsheet or write a ten-line program in Python or Mathematica, but it's not so trivial for many students, and they will need extensive guidance from elsewhere to be able to carry out such computations for themselves.
This makes the text incomplete in practical terms: any instructor wanting to use it would have to come up with extensive support materials to go with it.
This perhaps made some sense when these books were rather expensive to produce and distribute--but this time has passed.
Ben Crowell writes: "The economics of college textbooks is goofy, because the person who picks the book isn't the person who has to pay for it.This is a lively and very readable treatment of basic calculus.At 70 pages, it's a welcome antidote to the usual bloated textbooks, and the topics that are included match up pretty well with my own opinions of what it's really vital for a student to know after taking a calculus course.Although MIT's Open Courseware project gets most of the press, the movement started before that, and is going strong.In this article, I've reviewed five calculus textbooks that are either free as in speech or free as in beer." Read on for Crowell's take on each of the five books he's selected -- and pass the review on to any math teachers you know. As far as I can tell from the somewhat ambiguous notice on his web page, the book is intended to be licensed under the GPL copyleft license.The writing of textbooks and making them freely available on the web is an idea whose time has arrived.Most college mathematics textbooks attempt to be all things to all people and, as a result, are much too big and expensive.Combined with the increasing consolidation of the publishing industry, this has blown the lid off of textbook prices over the last decade.But remember what the World-Wide Web was basically about before the Dot-Com Detour?Although the very first page gives a nice clear explanation of what calculus is about, we then have to wait until about page 136 to learn any calculus.I say "about" because of the inconvenient way in which the book is split up into 54 separate PDF files, each of which has page numbers starting from 1.