loc@tmsoft.UUCP (Leigh Clayton) (01/11/91)
Another message from rbe@yrloc.ipsa.reuter.com (Bob Bernecky). >no. 4831177 filed 17.02.55 thu 10 jan 1991 >from rbe@ipsa >to loc@ipsa >cc clapl >subj merging in J > >@transferred from ipsa no. 4665548 filed 17.02.52 thu 10 jan 1991 > >One way to get the effect of x[i]?k in j is to use merge: > >x =. k i{x > >That is, merge the elements of k into positions i of x, and >assign the resulting array back into x. It is essentially a >functional form of indexed assignment, witut the side effect >which is present in APL of destroying the original array. > >The justification for making catenate work along the first axis >is that you only then need one functional form, comma, rather than >comma, comma-bar, and comma with bracket axis operator. The use >of rank reduces the number of primitives needed, simplifies the >teaching and use of the language, and unifies the treatment of >operations along other axes, by use of the rank adverb. > >Generally: > >APL J > >x,y x,"1 y >x?y x,y >x,[k]y x,"k y > >where k is origin 0. > >There is another way to do the merge, but I can't seem to make it work >in my version of J. Bob > ----------------------------------------------------------- - Men argue, Nature acts /Voltaire - ----------------------------------------------------------- loc@tmsoft.UUCP (Leigh Clayton) uunet!mnetor!tmsoft!loc