Is this bug the same as 13 : 'y+y' +
? On Fri, Sep 2, 2011 at 7:07 AM, Raul Miller <[email protected]> wrote: > On Fri, Sep 2, 2011 at 3:01 AM, Joey K Tuttle <[email protected]> wrote: > > Happily, it gives the same result as oof (even though complicated and > > obscure...) My use of the temporary z was just sloppiness - but I > > didn't notice that until I was flummoxed by making a tacit form - > > > > hooft =: 13 : '+/"1 ((i.y+1) =/ +/"1 z) [ z =. #: i. 2^y' > > > > and discovering that it produces a very different result (displaying > > the shape is sufficient to show that without wasting space). > > > > $hooft 6 > > 7 64 7 > > > > So clearly, 13 : failed. This rings a bell of something similar being > > reported before, but maybe it is different. I haven't succeeded in a > > simple expression that goes wrong in the same way. I'm sure someone > > in the forum can provide a tacit form that is similar, but works > > correctly - something other than - > > You can make that long expression tacit by breaking out the expression > which finds z: > 13 : 'z =. #: i. 2^y' > [: #: [: i. 2 ^ ] > > At this point the remaining expression has two variables: y and z. > This suggests using a hook for a monadic context. So we can replace y > wiith x and z with y: > > 13 : '+/"1 ((i.x+1) =/ +/"1 y)' > [: +/"1 ([: i. 1 + [) =/ [: +/"1 ] > > And then we plug the two phrases back into the parenthesis of (() ()): > > (([: +/"1 ([: i. 1 + [) =/ [: +/"1 ])([: #: [: i. 2 ^ ])) 6 > 1 6 15 20 15 6 1 > > Also, here is a simpler expression which probably illustrates the same > problem: > > '; ((y+1) ; , z) [ z =. 2+y' > > I found this by defining: > expr=: 1 :'((3 :m),&<(13 :m))' > > And then experimenting with sentences like: > $&.> 'experiment' expr 6 > until I had found a short one and then switching to > 'experiment' expr 3 > to simplify it further. > > FYI, > > -- > Raul > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA ^me^ at acm. org is my preferred e-mail ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
