On Fri, 01 Jun 2018 20:29:41 +0900
Jeong Dal
After inserting a line “save x, y;”, it works.
This is also defined as "clearxy ;" For those learning MetaPost, simplifying, z is defined as "(x,y)" so one can write z = (a,b) ; This is an EQUATION in MetaPost (x,y) = (a,b) ; not an assignment (as in most other languages), actually a pair of equations: x = a ; y = b ; When x and y are unknown, this can be "solved". When x and y contain values, it leads to "inconsistent equations". One *cannot* write z =: (a,b) ; ("=:" is the assignment operator), for z is just a macro, not a "pair" object or variable. This can be *very* confusing when learning MetaPost. Alan P.S. for i=0 upto n: z[i] = (i,0) ; endfor works as each element of the (pseudo)array z is unknown, at least the first time that it is used.