Hello everyone
My optimization problem is the following scenario:
1- Raw material (cotton) is needed at different locations to meet a minimum production workload
2- Production units are available at different locations.
3- Raw material costs vary every day, and are possibly different at each location.
4- Production machines consume cotton at two different rates (idle and peak).
5- Production time unit (say, shifts or days) may or may not be the same as the procurement time units. For instance, you can buy cotton once every day. You can do futures purchases based on projected future cost.
6- Our inventory may already have some cotton procured for a certain production intervals.
7- If I have excesss cotton at some unit, I can dispose of it in the market
I've implemented the model in AMPL and tried to solve it using minos solver, and I get the following error: "Unbounded or badly scaled problem." If I get rid of the selling option (point 7 above, by removing the Sell_Cotton term in the objective function, the solver finds and optimal solution.
Could you kindly take a look at the attached model and data file and suggest why this is a badly scaled problem?
Thanks and best regards
MyProblem.txtMyProblem-Data.txt
