Sure, ... The , , ,: approach is cleaner than the > ; ; ; approach (and it's generically useful both for symmetric numeric matrices and for constructing constant matrices).
Meanwhile, the -: trick is clever and concise (but not generic). Thanks, -- Raul On Wed, Oct 23, 2019 at 5:23 AM 'Mike Day' via Programming <[email protected]> wrote: > > Or: > > (+|:)-:0,3 0,4 3,:5 4 3 0 > > ? > > This generalises the lean but ad hoc expression: > -:@(+|:)@:(|.@(,\.))@:({. 3+i.@-@<: ) 5. NB. eg for 5 x 5 > 0 1.5 2 2.5 3 > 1.5 0 1.5 2 2.5 > 2 1.5 0 1.5 2 > 2.5 2 1.5 0 1.5 > 3 2.5 2 1.5 0 > ... the 3+ bit could be generalised with a bit more work... > > Mike > Sent from my iPad > > > On 23 Oct 2019, at 04:38, 'Jim Russell' via Programming > > <[email protected]> wrote: > > > > D=: (+|:)>'';1.5;2 1.5;2.5 2 1.5 0 > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
