Originally posted by: bluemoon32

Hello everybody,

I am new to CPLEX and trying to code a simple balanced transportation problem. I extract the data from excel file and I have mod. and dat. file. I dont think I have any problem in dat. file. 

I get an error message in mod. file. ( Name "i" does not exist. and Name "j" does not exist.) Anyone knows what am i missing in the code? I attached the question and my code on doc. file.

Thank you.

BM

Note that there is a dedicated OPL Forum here. You may be better off asking your OPL related questions there.

In any case, I think your constraints just use the wrong indices in the right-hand sides. Consider your constraints

  forall(i in plants)

  demand_const:

  sum (j in cities) x[i][j] >= demand[j];

  forall(j in cities)

  supply_const:

  sum(i in plants) x[i][j] <= supply[i];

In the first constraint I guess you mean demand[i] and in the second I guess you mean supply[j].

Originally posted by: bluemoon32

Thank you for the answer and the link.

Best,

BM