params_vb.vb


' Copyright 2017, Gurobi Optimization, Inc. */

' Use parameters that are associated with a model.

' A MIP is solved for a few seconds with different sets of parameters.
' The one with the smallest MIP gap is selected, and the optimization
' is resumed until the optimal solution is found.

Imports System
Imports Gurobi

Class params_vb
    Shared Sub Main(args As String())
        If args.Length < 1 Then
            Console.Out.WriteLine("Usage: params_vb filename")
            Return
        End If

        Try
            ' Read model and verify that it is a MIP
            Dim env As New GRBEnv()
            Dim m As New GRBModel(env, args(0))
            If m.IsMIP = 0 Then
                Console.WriteLine("The model is not an integer program")
                Environment.Exit(1)
            End If

            ' Set a 2 second time limit
            m.Parameters.TimeLimit = 2.0

            ' Now solve the model with different values of MIPFocus
            Dim bestModel As New GRBModel(m)
            bestModel.Optimize()
            For i As Integer = 1 To 3
                m.Reset()
                m.Parameters.MIPFocus = i
                m.Optimize()
                If bestModel.MIPGap > m.MIPGap Then
                    Dim swap As GRBModel = bestModel
                    bestModel = m
                    m = swap
                End If
            Next

            ' Finally, delete the extra model, reset the time limit and
            ' continue to solve the best model to optimality
            m.Dispose()
            bestModel.Parameters.TimeLimit = GRB.INFINITY
            bestModel.Optimize()

            Console.WriteLine("Solved with MIPFocus: " & bestModel.Parameters.MIPFocus)
        Catch e As GRBException
            Console.WriteLine("Error code: " + e.ErrorCode & ". " + e.Message)
        End Try
    End Sub
End Class

Try Gurobi for Free

Choose the evaluation license that fits you best, and start working with our Expert Team for technical guidance and support.

Evaluation License
Get a free, full-featured license of the Gurobi Optimizer to experience the performance, support, benchmarking and tuning services we provide as part of our product offering.
Academic License
Gurobi supports the teaching and use of optimization within academic institutions. We offer free, full-featured copies of Gurobi for use in class, and for research.
Cloud Trial

Request free trial hours, so you can see how quickly and easily a model can be solved on the cloud.

Search