Hi, Just sharing a thought.
I was flicking through this old text book "The Science Of Programming" by David Gries (1981), while thinking that it was one of the few I remembered -- it made an impression on me. Here's a quote: "Wouldn't it be nice to be able to run a program backwards or, better yet, to derive from one program P a second program P-1 that computes the inverse of P? That means that running followed by P-1 would be the same as not running any program at all! Also, if we had the result of executing P, but had lost the input, we could execute P-1 to determine that input. " -Steven ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
