modelling facility location problem

GAMS
1

Hi ! I’m new on GAMs .

I try to modelling an undesirable facility location problem.

But I try to make a loop but I not.


sets

i müşteri /A,B,C,D/

j tesis /A,B,C,D/

M yakınlık derecesi /1*4/ ;


scalar

P açılacak tesis sayısı /2/ ;





parameters

h(i) i müşterisinin talebi

/

A 3
B 4
C 2
D 5

/ ;

table d(i,j) i müşterisinin j tesisine uzaklığı


A B C D
A 0 3 7 12
B 3 0 4 9
C 7 4 0 5
D 12 9 5 0 ;

table t(i,m )


1 2 3 4
A A B C D
B B A C D
C C B D A
D D C B A ;



binary variable
y(i,j)
x(j) ;




variable

z ;


equation

amac
k1
k2
k3
k4
;




amac…z=e=sum((i,j),h(i)*d(i,j)*y(i,j)) ;
k1(i)…sum(j,y(i,j))=e=1;
k2… sum(j,x(j))=e= P;
k3(i,j)…y(i,j)=l=x(j) ;
k4(i)…sum(M, y(i,t(i,m)))-x(i,m)=g=0;






model undesirable /all/;



scalar

minM /1/
maxM /4/;


for ( M=1 to 4 by 1 ;

x(i,m) =e= x(t);


solve undesirable using MIP maximizing z;
);

display z.l,x.l , y.l ;







there is error for table t(i,m) " real number expected " … how can I fix it?

2

Hi
A table, as Gams tells you, should contain numerical values, not set elements.
I suggest you have a look at the examples in the Gams library on network and facility location problems to learn how to model this kind of problems.
Cheers
Renger