Hahaha! For my testing process I went through the book blindly executing every code-block in turn. I don't know how I missed a footnote for that one. I guess I felt I couldn't add anything to Eugene's preceding phrase: "...at the heart of it..."
...So a lot has gone before. I supposed readers would rumble the fact that something got lost in the extraction. :) Seriously though, please add a note to the Wiki if something non-plusses you or is otherwise worth an observation. The chapters are still there -- and can be accessed from the page: http://www.jsoftware.com/jwiki/At%20Play%20With%20J . They will stick around collecting annotations from the J community until we have enough for a 3rd edition. This must be the first printed textbook that has been crafted to turn into an on-line conference. Hitherto it's been the other way round, with the conference proceedings published after the event, and bequeathed to students to wipe the dust off. Rather wonderful when you think of it. Thank you all for making it possible. And I can genuinely say the book has taught me J from scratch. I'm now a serious J user, by my own lights. Incidentally if you've got the ebook and would like a better format for copy/pasting the code into the J session on your palmtop, I can email you a text-only version. All the diagrams and other fancy stuff is lost, but it works fine when loaded into Word Mobile. I'll have to find the time to make a "lab" out of it. It goes without saying that on anything bigger than a palmtop the best way of re-running code is from the Wiki pages and not from the PDF. Ian On Fri, Jan 15, 2010 at 9:50 PM, Devon McCormick <[email protected]> wrote: > I opened my newly-received copy of "At Play With J" today to the article on > Jacobi's method. Imagine my dismay at reading the first two lines of J code > which I am unable to run as they depend on (at least) two definitions not > given. In > > r=. ((cos,-sin),sin,cos) (ia R)} I > Q=. q ip |:r [ R=. r ip R ip |:r > > what are "ip" and "ia"? Am I missing something here in terms of a > reference? > > > -- > Devon McCormick, CFA > ^me^ at acm. > org is my > preferred e-mail > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
