Hi there!
I am pretty new in using GAMS, so I could not find a solution to my problem, despite all my research.
I am trying to define a variable with 3 dimensionsi X(i,j,k), however, i have some data points of this variable, so I would like to enter those values in this variable also. I wonder if anyone can help me figure that out.

Hi
It is not completely clear to me what you are looking for: If you know the solution for some of the variable X, you just have to fix them to that value, e.g.

if you want to define let’s say three dimensional parameter you can do it as in the following example:

Set
i /s, n1, n2, t/
j /s, n1, n2, t/
k /1*2/;
*or you can use Alias(i,j); if in your case they're the same sets like in my example
Table c(i,j,k)
s.1 n1.1 n2.1 t.1 s.2 n1.2 n2.2 t.2
s 0 5 1 0 0 3 1 3
n1 2 1 1 2 0 1 1 1
n2 0 5 1 0 3 1 4 1
t 10 1 1 0 0 2 1 1;

Index i is used for rows; (j,k) in this order is used for columns. As you may see (j,1), where k =1 is the first half of the table and the second half of the table is for (j,2), where k=2. Hope this helps and sorry with badly shifted table.