$ondollar title River Power (ILP) Example 12.2 of Rardin (1998)

$offsymxref offsymlist offuelxref offuellist offupper
option limrow = 0, limcol = 0;

set j "generators" /1*4/;

parameter c(j) "cost of using generator j"
/1 7, 2 12, 3 5, 4 14/;

parameter p(j) "power of generator j"
/1 300, 2 600, 3 500, 4 1600/;

free variable cost "total cost";

binary variable x(j) "whether to use generator j";

equations
obj    "min total cost",
dem    "meet demand";

obj..
cost =e= sum(j, c(j)*x(j));

dem..
sum(j, p(j)*x(j)) =g= 700;

model rivpower /all/;

solve rivpower using mip minimizing cost;