I've been running to too many situations that I uses 4$.$.y a lot to get indexes of all non zero elements to an array, I wonder if there are any alternative ways to do that in J, especially when y is a boolean array.
Also monadic I. only works for 1D array, while ⍸ from APL works for higher dimension cases, how to implement this in J? LdBeth ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
