They shouldn't agree, and they are both correct. u@:v y is u v y
([: u v) y is u v y u@v y is u@:v"v y which differs in rank: |:@:*:"*: is not the same as |:@:": Henry Rich On 2/5/2012 11:00 PM, Linda Alvord wrote: > Shouldn't these agree? > > (|: @ *:)i. 2 2 > 0 1 > 4 9 > ([: |: *:)i. 2 2 > 0 4 > 1 9 > > And isn't the second one correct? > > Linda > > > -----Original Message----- > From: programming-boun...@jsoftware.com > [mailto:programming-boun...@jsoftware.com] On Behalf Of Brian Schott > Sent: Sunday, February 05, 2012 4:25 PM > To: Programming forum > Subject: Re: [Jprogramming] Another early morning exercise > > Kip may be onto something that at least for me shows a little of the > problem of going from an expression with @ to one without. For example > in the first 3 execution below, the first two produce the same result, > but the third, does not. > > (|: @ *:) i. 2 2 > 0 1 > 4 9 > 13 : '|: @ *: y' i. 2 2 > 0 1 > 4 9 > 13 : '|: *: y' i. 2 2 > 0 4 > 1 9 > > To me, the way to make the errant third one above conform is to > include the rank operator in the defintion as follows. > > 13 : '|:"*: *: y' i. 2 2 > 0 1 > 4 9 > > > On the other hand the third of these next 3 *does* produce the same > result because @: automatically implies the rank of the previous > example. > > (|: @: *:) i. 2 2 > 0 4 > 1 9 > 13 : '|: @: *: y' i. 2 2 > 0 4 > 1 9 > > On Sun, Feb 5, 2012 at 2:41 PM, km<k...@math.uh.edu> wrote: >> (|: @ *:) i. 2 2 >> 0 1 >> 4 9 >> >> Composition? >> >> Sent from my iPad >> >> >> On Feb 5, 2012, at 8:16 AM, Boyko Bantchev<boyk...@gmail.com> wrote: >> >>> On 5 February 2012 14:11, Linda Alvord<lindaalv...@verizon.net> wrote: >>>> My goal has been to translate from expressions with @ to ones without > it. >>> >>> You also mentioned eliminating @ in another thread. >>> Why do you consider it important? >>> @ is the composition of functions – and is composition not the most >>> natural operation on functions that one could think of? > > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
