[Help-glpk] Re: glpk

[Andrew Makhorin]

> I do not belong to the OR community. Anyway I need Linear Programming to
> solve a problem. I start using glpk with diffilculty.  At least I would
> have expected that just adding a display statement in one of the  simple
> example file provided with glpk would entail no problem.
> 
> I just ran glpsol --model bpp.mod with some display statement added (see
> below (111)) and obtained (222). I don't understand this behaviour since
> the glpk lang.ps documentation explicitly  shows that such statements as
> display{i in I, j in J}: i,j,x[i,j];  are allowed.

If you wish to see results of optimization, you should specify the solve
statement preceding the display statement, that is:

...
minimize obj: sum{j in J} used[j];
/* objective is to minimize the number of bins used */

solve;

/* C.S. 15/12/05 */
display '*************************';
/* display{j in J}: j, used[j]; */
display '*************************';
/* display{i in I}: i; */
/* display{j in J}: j; */
display{ii in I, jj in J}: ii,jj,x[ii,jj];
...