I found a series of blog postings by Conal Elliott on the generalization of derivatives. Others may also enjoy them, so here's the URI:
http://conal.net/blog/ Perhaps most interesting is the one entitled "Higher-dimensional, higher-order derivatives, functionally". In that posting the chain rule is given by the following expression: deriv (f . g) x = deriv f (g x) . deriv g x I'm confused by the use of composition on the right-hand side, as I expect it to involve two functions. I can't see a composition of two functions here; in J terms, I see nouns where I expect verbs. Guidance in correcting my misinterpretation is welcome. Tracy ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
