Originally posted by: Morianta
Hi,
I'm developing a mathematical model for my thesis, whose objective function doesn't seem to be quadratic, and generally, non-linear. However, I encounter the error related to the indefiniteness of matrix Q. Could you please guide me what the problem might be?? The following is part of my code:
using CPLEX;
int n=...;//Number of customers
int N=2*n;//Number of customer nodes
int T=...;
range Nodes=0..N+1;
range Periods=1..T;
range Linehauls=1..n;
range Backhauls=n+1..N;
float Hd[0..n]=...;//Unit delivery unit time holding cost
float Hp[n+1..N+1]=...;//Unit pichup unit time holding cost
int c[Nodes][Nodes]=...;//Unit cost of transportation from consumer i to j
dvar int+ Id[0..n][Periods];//Inventory level of serviceable product at the depot
dvar int+ Ip[n+1..N+1][Periods];//Inventory level of cores at the depot
dvar boolean x[Nodes][Nodes][Periods];
dvar boolean y[Nodes][Periods];
dexpr float DeliveryHoldingCost=sum(i in 0..n, t in Periods)(Hd[i]*Id[i][t]);
dexpr float PickupHoldingCost=sum(j in n+1..N+1, t in Periods)(Hp[j]*Ip[j][t]);
dexpr float TransportationCost=sum(i,j in Nodes:i!=j, t in Periods)(c[i][j]*x[i][j][t]);
minimize DeliveryHoldingCost+PickupHoldingCost+TransportationCost;
...
Error:
CPLEX Error 5002: Q in 'id1399' is not positive semi-definite. General Unknown OPL Problem Marker
Thank you so much.
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