The specification was > Ok, I'm wondering how I might find the number 4 in a rank-2 array > using dyadic i.
in the context of novice user. --- Dan Bron <[EMAIL PROTECTED]> wrote: > Oleg asked: > > Why so complicated? > > Because it does more, and is more general. To add value to the thread, as > simple solutions had > been previously supplied. > > Concretely, if you intend this: > > OK> [EMAIL PROTECTED] #: i.&, > > to replace this: > > DB> E.&>/@:((>. - ,)&:(#@:$) ,:@:]^:[&.> ,&:<) > > You will be unhappily suprised: > > 0 1 2 dbp i. 2 2 3 > 0 0 0 > > 0 1 2 okp~ i. 2 2 3 > 0 0 0 > 0 0 1 > 0 0 2 > > 4 5 dbp i. 2 2 3 > 0 1 1 > > 4 5 okp~ i. 2 2 3 > 0 1 1 > 0 1 2 > > Otherwise if you intended to replace idx0 =. $ #: I.@:, then note that (A) > you cannot claim > the advantage of "decreased complexity", (B) idx0@:= will return ALL the > indices where x = y > whereas okp will only return the FIRST index, and (C) the verb idx0@:f > will return the > indices where the predicate f holds, for any predicate at all. Therefore > okp is less > general. > > -Dan > > PS: Plus ,:^:(difference in rank) is cool! The sentence x -: #@:$ ,:^:(x > -~ #@:$y) y is a > tautology, no matter whether x -~ #@:$ y is positive, negative, or zero! __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
