This expression is sufficiently dense that it might merit being broken into a few more lines on which you define some meaningful auxiliary verbs to be used in the top-level routine. I'm not familiar with the algorithm, so I can't suggest what these might be.
Looking at the one that's there, I'm a bit annoyed by its use of "adverb define" which means it doesn't run if I cut and paste it into a J session unless I have those "helpers" defined. On Thu, May 10, 2012 at 4:12 PM, Raul Miller <rauldmil...@gmail.com> wrote: > On Thu, May 10, 2012 at 1:46 PM, Aai <agroeneveld...@gmail.com> wrote: >> The J contribution on Rosetta Code >> http://rosettacode.org/wiki/Runge-Kutta_method#J for subject is a loopy >> one. My goal is to change that into a more functional and J-ish one. >> >> Here's my attempt for that particular task: >> >> p4=: 1 :(':';'({:y)+6%~+/1 2 2 1*(x*[: u y+(*x&,@{:))/\.1 0.5 0.5,x*u y') >> >> rk4M=: 1 :0 >> 'Y0 a b h'=. 4{. y >> (,.[:h&(u p4)@(,{:)/\.Y0,~}.)&.|. a+i.@>:&.(%&h) b-a >> ) >> >> (fyp rk4 -: fyp rk4M) 1 0 10 0.001 >> 1 > > As a minor point, I think I would change the definition of p4 > to use the same definition format as rk4M > > p4=: 1 :0 > : > ({:y)+6%~+/1 2 2 1*(x*[: u y+(*x&,@{:))/\.1 0.5 0.5,x*u y > ) > > But I do not have the time to focus on this one. > > I hope I'm not overlooking anything important. > (I wonder if the parenthesized expressions deserve names?) > > Thanks for tackling this! > > -- > Raul > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm -- Devon McCormick, CFA ^me^ at acm. org is my preferred e-mail ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
