Lingo 错误63

题目

Lingo 错误63
sets:
x/1..49/:a,N;
y/1..49/:S;
XY(x,y):cost,M;
endsets
min=@sum(x(j):a(j)*N(j))+@sum(y(i):S(i));
@for(xy(i,j)|a(j) #eq# 0:cost(i,j)=100000000);
@for(xy(i,j)|a(j) #ne# 0:cost(i,j)=M(i,j));
@for(y(i):S(i)=@min(XY(i,j):cost(i,j)));
@for(x(j):@bin(a));

答案

循环函数的下标不可以是未知的 你这里a是未知的所以不可以