\starttext \startMPcode u:=1cm ; path p, q ; p=fullsquare scaled u ; q=fullsquare scaled u shifted (4u,-2u) ; draw p ; draw q ; drawarrow center p--center q ; label(btex $5$ etex,center p) ; label(btex $-2 $ etex,center q) ; \stopMPcode \stoptext
How about something like below. I'm not sure exactly how ncline works in PStricks, but this macro takes 4 arguments, namely a point, its corresponding label, a second point, and its corresponding label. \starttext \startMPcode vardef ncline (expr A,h,B,k) = save p,q; path p,q; label(h,A); p:=fullsquare scaled u shifted A; draw p; label(k,B); q:=fullsquare scaled u shifted B; draw q; drawarrow (A--B) cutbefore p cutafter q; enddef; u:=1cm ; ncline(origin,btex $5$ etex,(4*u,-2*u),btex $-2$ etex); \stopMPcode \stoptext Troy Henderson