数学建模LINGO某基金管理人的工作是,每天将现有的美元、英镑、马克、日元四种货币按当天汇率相互兑换,使在满足需求量的条

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model:
sets:
currency/1..4/:amount,demand,a;
link(currency,currency):exchange,rate;
endsets
data:
demand=6 3 1 10;
amount=8 1 8 0;
rate=
1 0.58928 1.743 138.3
1.697 1 2.9579 234.7
0.57372 0.33808 1 79.346
0.007233 0.00426 0.0126 1;
enddata
max=@sum(currency(i):a*(rate(i,1)+1/rate(1,i))/2);
@for(currency(j):a(j)=@sum(currency(i):rate(i,j)*exchange(i,j)));
@for(currency:a>=demand);
@for(currency(i):amount(i)>=@sum(currency(j):exchange(i,j)));
@for(link(i,j)|j#ne#i:exchange(i,j)*exchange(j,i)=0);
end