Note that re-using one of the internal names gives a slight improvement in space and a corresponding one in time:
c3=: 3 : 0 a=. 2|y c=. 2+6*y c=. a } y ,: c (_1 & (33 b.)) c ) 100 ts 'c2 a' 0.0196169 2.62189e7 100 ts 'c3 a' 0.0170517 1.78303e7 Though I would normally rate these timings as basically the same since the difference is relatively small. On Thu, Aug 7, 2014 at 9:24 AM, Raul Miller <[email protected]> wrote: > That was my original impression. > > But then I looked at the right hand side of the expression: > > Why is it labelled x,y,:z and why does the text mention the case > c}x,y,...,:z? > > It might be that this was originally a more ambitious project and that > Roger got interrupted before he finished it. > > Anyways, it is interesting to me that the wiki page is silent about this > explicitly documented issue. > > -- > Raul > > > > On Thu, Aug 7, 2014 at 8:53 AM, Henry Rich <[email protected]> wrote: > > > 'boolean' here means that 3!:0 returns 1; the values are restricted to > > {0,1}. Details at > > > > http://www.jsoftware.com/jwiki/Vocabulary/SpecialCombinations# > > Assignments_In_Place_.28AIP.29 > > > > > > Henry Rich > > > > > > On 8/7/2014 8:42 AM, Raul Miller wrote: > > > >> I think http://jsoftware.com/help/release/iamend.htm might be relevant. > >> > >> Note also that in this case I'm not sure if "boolean" really means > >> "non-negative integer". (If I understand properly: in George Boole's > >> arithmetic these were equivalent, and some of the details here suggest > >> that > >> that original meaning might be relevant here. It's a confusing topic > >> though > >> because it has become popular, depending on context, to assert that > >> "boolean" can only refer to the values 0 and 1 and also that "boolean" > >> cannot be used to refer to the values 0 and 1.) > >> > >> Thanks, > >> > >> ---------------------------------------------------------------------- > > For information about J forums see http://www.jsoftware.com/forums.htm > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > -- Devon McCormick, CFA ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
