On Wed, 2 Nov 2011, Riccardo (Jack) Lucchetti wrote: Sorry for the noise: (1) I forgot to send my previous message to the users' list; (2) there was a small glitch in func2 (corrected below); (3) I'd like to express my point more explicitly: IMO, base types such as matrices should stay as unencumbered by extra info (or metadata, call it what you want) in the interest of efficiency. If you really need to wrap up a complex set of information into one entity, that's exactly what bundles are for. <hansl> set echo off set messages off function string func1(scalar r, scalar c, matrix *m) string rl = "" loop i=1..r --quiet sprintf rl "%s,row_%d", rl, i end loop string cl = "" loop i=1..c --quiet sprintf cl "%s,col_%d", cl, i end loop m = zeros(r,c) sprintf ret "%s %s", rl, cl return ret end function function bundle func2(scalar r, scalar c) bundle ret string rl = "" loop i=1..r --quiet sprintf rl "%s row_%d", rl, i end loop ret["Rlab"] = rl string cl = "" loop i=1..c --quiet sprintf cl "%s col_%d", cl, i end loop ret["Clab"] = cl m = zeros(r,c) ret["X"] = m return ret end function # ----- using func1 ----------------------------- a = {} boo = func1(3,2,&a) rowlab = strsub(strsplit(boo, 1), ",", " ") collab = strsub(strsplit(boo, 2), ",", " ") rownames(a, rowlab) colnames(a, collab) print a # ----- using func2 ----------------------------- bundle zoo = func2(3,2) rowlab = zoo["Rlab"] collab = zoo["Clab"] a = zoo["X"] rownames(a, rowlab) colnames(a, collab) print a </hansl> Riccardo (Jack) Lucchetti Dipartimento di Economia Università Politecnica delle Marche r.lucchetti(a)univpm.it http://www.econ.univpm.it/lucchetti