I am writing a code for a simple transportation problem in IBM ILOG CPLEX Optimization Studio. Here is the code trans.mod (File)
{string} Sources = ...;
{string} Destination = ...;
float Demand[Destination]= ...;
float Output[Sources]= ...;
float Shipcost[Sources][Destination]= ...;
assert sum(s in Sources) Output[s] == sum(d in Destination) Demand[d];
dvar int Ship[Sources][Destination] in 1..50;
minimize
sum(s in Sources, d in Destination)
Shipcost[s][d]*Ship[s][d];
subject to
{
forall( s in Sources , d in Destination )
sum(d in Destination)
Ship[s][d]<=Output[s];
forall( s in Sources , d in Destination )
sum(s in Sources)
Ship[s][d]>=Demand[d];
forall( s in Sources , d in Destination )
Ship[s][d]>=0;
}
execute DISPLAY
{
writeln("Ship=",Ship)
}
The data file of it is as trans.data
Sources = {Source1 Source2 Source3};
Destination = {mumbai delhi vadodra kolkata};
Demand = #[
mumbai: 80
delhi: 65
vadodra: 70
kolkata: 85
]#;
Output = #[
Source1: 75
Source2: 125
Source3: 100
]#;
Shipcost = #[
Source1: #[
mumbai: 464
delhi: 513
vadodra: 654
kolkata: 867
]#
Source2 : #[
mumbai: 352
delhi: 416
vadodra: 690
kolkata: 791
]#
Source3 : #[
mumbai: 995
delhi: 682
vadodra: 388
kolkata: 685
]#
]#;
The problem is that when I run this simple transportation problem on TORA it gives me Optimal Solution as 152535 But when I run this code on cplex it gives me optimal solution as 156366 Please let me know where I am going wrong or why i am getting the difference of 3831. Thank you in advance.