## Xii >= Xij how to code in GAMS

Problems with modeling
lixlz51
User
Posts: 11
Joined: 8 months ago
Location: University of Nottingham, UK

### Xii >= Xij how to code in GAMS

Hi everyone,
I am learning GAMs to solve a NLP model. I want to specify that the local demand is prioritized before the warehouse can be used for stores in other region. so how to express Xii>=Xij in gams? I was trying to use the following

set i 'warehouse' /1*3/;
alias(i,j); *each warehouse is assigned to each local store for replenishment, so the set for warehouse and store is the same

variable
x(i,j) 'warehouse i is used to replenish demand for store j';

eq(warehouse).. X(''i,i'') =ge= X(''i,j'')\$i ne j;

how can i correct this to express Xii>=Xij while i is not equal to j? Thank you a million for your help!

Manassaldi
User
Posts: 75
Joined: 2 years ago
Location: Rosario - Argentina

### Re: Xii >= Xij how to code in GAMS

Hi, it's simple

set i warehouse /1*3/;
alias(i,j);

eq(i,j)\$(ord(i) ne ord(j)).. X(i,i) =g= X(i,j);

Bye

lixlz51
User
Posts: 11
Joined: 8 months ago
Location: University of Nottingham, UK

### Re: Xii >= Xij how to code in GAMS

Manassaldi wrote:
8 months ago
Hi, it's simple

set i warehouse /1*3/;
alias(i,j);

eq(i,j)\$(ord(i) ne ord(j)).. X(i,i) =g= X(i,j);

Bye
Hi Really appreciate your help! Have a good day