$title unbnd: unbounded linear program

set index_set/i1, i2/;

positive variable x(index_set);
variable profit;

equation
	objective       "define cost"
        constraint      "a single constraint"
;

objective..
	profit =e= 2*x('i1') + 3*x('i2');

constraint..
	sum(index_set, x(index_set)) =g= 5;

model unbdlp/all/;

* if we maximize, the problem is unbounded
solve unbdlp using lp maximizing profit;

* if we minimize, the problem has a solution.
solve  unbdlp using lp minimizing profit;