Search found 6 matches

by sivudu
4 years ago
Forum: Modeling
Topic: Decomposition Methods
Replies: 0
Views: 1960

Decomposition Methods

Decompose.pdf[/attachmen Can I apply any one of the Decomposition methods (lagrangian or Benders or Dantzig-wolfe ) to the optimization Problem shown in the attachment and can I get any advantage (shorter computing time) if the indices are very large. Thank you.[attachment=0]Decompose.pdf
by sivudu
5 years ago
Forum: Modeling
Topic: Transportation problem
Replies: 1
Views: 2436

Re: Transportation problem

The following parameter is shown as negative in your code in the attachment. If you correct that parameter to positive value you may get the desired answer.

Transportation_cost("Waste","Area1") = -10;
by sivudu
5 years ago
Forum: Modeling
Topic: gradient of LPP in GAMS
Replies: 0
Views: 1709

gradient of LPP in GAMS

Can we get gradients of an objective function of the linear programming problem in GAMS. If we can get, what command is used to get it.
by sivudu
5 years ago
Forum: Modeling
Topic: rmip solver in GAMS - Reg
Replies: 1
Views: 2179

rmip solver in GAMS - Reg

I want to know what is rmip solver in GAMS. when it is used. I saw that the lagrangian relaxation example in GAMS model library used rmip solver to solve the problem. in what way the rmip solver is different from lp and mip. please elaborate.
by sivudu
6 years ago
Forum: Modeling
Topic: Lagrangian Decomposition - GAMS
Replies: 1
Views: 2559

Re: Lagrangian Decomposition - Constraint Violation - GAMS

I want to know why one constraint in the lagrangian solution is violated. The constraint in (DP2) sub-problem is violated.

The solution, i got is

Code: Select all

X1=0
X2=4
X3=8
X4=0
X5=0
X6=0
X7=2.
This solution violates the constraint

Code: Select all

X6+6X7<=9 
in (DP2) sub-problem.

please guide me.
by sivudu
6 years ago
Forum: Modeling
Topic: Lagrangian Decomposition - GAMS
Replies: 1
Views: 2559

Lagrangian Decomposition - GAMS

I wanted to solve a L.P.P using lagrangian decomposition. The problem consists of 3 sub-problems(DP1,DP2,DP3) and 3 coupling constraints. The 3 sub-problems are (DP3) Max X1+2X2+X3 s.t X1+X2<=6 X1+2X2<=8 X3<=10 X3<=2X2 X1,X2,X3>=0 (DP1) Max 5X4+2X5 s.t 2X4+X5<=9 X4,X5>=0 (DP2) Max 3X6+X7 s.t X6+6X7<...