I had A=: 0&(;@:) u A y
My u raises an error if y is bad, in which case EMPTY is a reasonable result. I'd prefer not checking y in each u. What is the tacit A=: 1 : '0&(;@:u) :: empty' ? Thanks, Dave. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
