I am working on a MILP model about aggregate planning. The problem is that at the end I defined two auxiliary variables to save the values of cost (f1) and staff layoffs (f2) and my objective function is a simple subtraction: z: f1 -f2; and the results are very weir:
z = 2129100
f1 = 2129150
f2 = 45
As is evident, z is not the subtraction of f1 and f2, there are 5 units that are missing. What’s going on here? Thank you for being so helpful.
I am using Cplex with cplex_options ‘mipgap 0’; the complete model (mod, dat and run files) is available at: https://pastebin.com/u3GMF2aw