June, I find (@:[)(^:]) unappealing. I prefer the dyadic invocation of a bonded monad, ie. x m&v y or x u&n y , particularly when the primary argument will be the number of iterations, and some seed data is required for the intial iteration.
See my earlier responses to this thread for an example. -Dan ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
