I've been playing with the expression at http://en.wikipedia.org/wiki/Correlation c=.(*&s-~#@[*s@:*)%*&(s(-~(#*s=.+/))&.:*:]) 1 3 2 4 c 2 4 3 3.5 0.831522 c is as short as I can get. Could you come up with a verb for correlation, shorter than c?