AMPL语法错误“;”

Question

AMPL新手，在以下型号中选择“＆gt;＆gt;＆gt;＆gt;＆gt ;;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;＆lt;”作为问题：

set Types;
param demand {Types};
set Machines;
param prod_cost {Machines, Types};
param days_reqd {Machines, Types};
param days_avail {Machines};

var x {Machines, Types} >=0;  # amount produced

minimize  total_cost:  sum {m in Machines, t in Types} prod_cost[m,t] * x[m,t] ;

subject to  machine_capacity: sum {m in Machines, t in Types} x[m,t] * days_reqd[m,t] <= days_avail[m] ;

subject to  satisfy_demand: sum {m in Machines, t in Types} x[m,t] >= demand ;

Answer 1

demand参数在集合Types上建立索引，因此需要下标，例如

subject to  satisfy_demand{t in Types}:
  sum {m in Machines} x[m,t] >= demand[t] ;