The General Algebraic Modeling System (GAMS)是一款數學規劃和優化的高級建模系統。本文簡單通過一個例子簡單介紹GAMS的用法。
GAMS官方網站:http://www.gams.com/
例子:運輸問題基本模型
代碼:
sets
i canning plants /seattle, san-diego/
j markets /new-york,chicago,topeka/;
parameters
a(i) capacity of plant i in cases
/
seattle 350
san-diego 600
/
b(j) demand at market j in cases
/
new-york 325
chicago 300
topeka 275
/;
table d(i,j) distance in thousand of miles
new-york chicago topeka
seattle 2.5 1.7 1.8
san-diego 2.5 1.8 1.4 ;
scalar f freight in dollars per case per thousand miles /90/;
parameter c(i,j) transport cost in thousand of dollars per case;
c(i,j) = f*d(i,j)/1000;
variables
x(i,j)
z;
positive variable x;
equations
cost
supply(i)
demand(j);
cost.. z =e= sum((i,j), c(i,j) * x(i,j)) ;
supply(i).. sum(j,x(i,j)) =l= a(i);
demand(j).. sum(i,x(i,j)) =g= b(j);
model transport /all/
solve transport using lp minimizing z;
display x.l,x.m;