Generate data using for loop in GAMS

Question

plan is a matrix in data.

for i = 1:5
  for j = 1:3
    for k = 1:plan(j,i)
      C(i,j,k) = SUB(j,i);
    end
  end
end

How to model same in GAMS. Please help.

Answer 1

Loops are often overused by users unfamiliar with GAMS. In GAMS explicit loops are the exception: usually we want to use implicit loops. Like:

c(i,j,k)$(ord(k)<=plan(j,i)) = sub(j,i);

Answer 2

First thing is that you have to think about the final output C as a matrix with given dimensions. That is, the size of the third dimension k must be determined before hand. Probably as the maximum of all plan(j,i) values. So I am going to call the maximum value of the index k as capital K. In that case you can do that as follows:

SET i /1*5/;
SET j /1*3/;
SET k /1*K/;

Loop (i,
  Loop (j,
    Loop (k,
      If (ord(k) <= plan(j,i), C(i,j,k) = SUB(j,i););
    );
  );
);