Roger Hui <[email protected]> writes: > The following was written by Ken Iverson in 1966 > http://www.jsoftware.com/papers/EvalOrder.htm > and is relevant to your example.
Thanks. I'd seen that before, when experimenting some with polynomials. It certainly demonstrates that APL-like notation is precise and concise, but (at least for now) I find it a little harder to manipulate. > For example, instead of +/(y-ym)^2 , write > +/ *: y-ym > > +/((y-f)-(ym-f))^2 > +/ *: (y-f) - (ym-f) > > (+/(y-f)^2)+(+/(f-ym)^2)+2*+/(y-f)*(f-ym) > (+/*:y-f) + (+/*:f-ym) + +: +/ (y-f) * (f-ym) That does look clearer. While I don't find the replacement of 2* with +: to help, replacing ()^2 with *:() definitely does. > Another advantage of J notation over CMN, > is that you can begin by assigning typical > values for y, ym, and f, and as you are evolving > the line you can enter each line into the > computer and verify that they give the same > results from line to line. I did this exact thing, and I definitely found it to be helpful. In addition, it gave me some rough magnitude intuition into the various components of the sums that I wouldn't have if just writing out the algebra. Regards, Johann ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
