> From: Brian Schott > I have become more and more comfortable with the permutation > vectors associated with grade up and grade down.
Grade and iota (diadic) are two very powerful operations. In good old days of flat APL 90% (*) of a job now done by cut conjunction, key adverb, boxing and each was done by clever applications of diadic iota and grade. Sure, cut and key are very straightforward and easy to use and it was a wise choice to add them to the language to make it more practical, but the downside is that if you do not excersize your grade muscle you will never know true value of it and will not be able to use it in nontrivial cases. To illustrate try to write grp +//. values b >./;.1 values ; b <@/:~;.1 values (all very natural for writing reports operations) without cut, key and boxing (which were not available in APL) ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
