Hi John, The original code I'm using is a C implementation of Storn's Differential Evolution (DE) algorithm (http://www.icsi.berkeley.edu/~storn/code.html). The polynomial function was used as a demo of function fitting by the algorithm. The C-code I used was by Peter Turney (http://www.icsi.berkeley.edu/~storn/code.html#csou). It (and other versions) uses the asymmetric cost calculation.
DE lends itself quite well to J implementation - nothwithstanding my problems with the polynomial cost function :-) As someone new to J, I'd very much like feedback on the final version when I complete it. On an historical note, I used to program in APL on an IBM/360 in the 1970's. My university also had a few portable APL ttys with acoustic couplers attached with which you could dial up the system from home. I didn't encounter anything like that quality of interactivity until many years later. Ronan On 28/06/2006 15:24, "John Randall" <[EMAIL PROTECTED]> wrote: > I'm confused here. > > Should Ronan's C code really be > > if (px<-1.0 || px>1.0) result+=(1.0-px)*(1.0-px); > > or > > if (px<-1.0 || px>1.0) result+=(-1.0-px)*(1.0-px); > > The latter is more symmetrical, and is also continuous, which the first is > not. It's also easily implementable as > > f=:0 >. <:@:*: > > Best wishes, > > John > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Ronan Reilly Department of Computer Science NUI Maynooth Maynooth Co. Kildare IRELAND t: +353-1-7083847 e: [EMAIL PROTECTED] w: http://www.cs.nuim.ie; http://cortex.cs.nuim.ie ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
