Here is a simple idiom for testing whether a number x is contained within a semi-open interval [y1,y2). The problem itself is so simple and commonplace that this solution is probably known to others, but I don't recall to have seen it on J's web pages and it occurred to me only yesterday, so here it is: </@:< . E.g.:
2.4 (</@:<) 2 3 1 (-:-:i.10) (</@:<)"0 1 (1 2) 0 0 0 0 1 1 1 1 0 0 The simplicity of the expression I attribute to the algebraic elegance characteristic for semi-open intervals. ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
