FICO
FICO Xpress Optimization Examples Repository
FICO Optimization Community FICO Xpress Optimization Home
Back to examples browserPrevious exampleNext example

Collecting all solutions with the MIP solution pool

Description
We take the power generation problem stored in hpw15.mps which seeks to optimise the operating pattern of a group of electricity generators. We solve the problem collecting all solutions found during the MIP search. The optimal solution's objective and solution values are printed to screen.

mipsolpool_dnet.zip[download all files]

Source Files
By clicking on a file name, a preview is opened at the bottom of this page.
MipSolPool.cs[download]
MipSolPool.csproj[download]

Data Files





MipSolPool.cs

/***********************************************************************
   Xpress Optimizer Examples
   =========================

   file MipSolPool.cs
   ``````````````````
   Generate all solutions with the MIP solution pool

   We take the power generation problem stored in hpw15.mps which seeks to
   optimise the operating pattern of a group of electricity generators. We
   solve the problem collecting all solutions found during the MIP search.
   The optimal solution's objective and solution values are printed to
   screen.

   (c) 2008,2021 Fair Isaac Corporation
********************************************************************/

using System;
using System.IO;
using Optimizer;

namespace XPRSExamples
{
    class MipSolPool
    {
        static void Main(string[] args)
        {
            XPRS.Init();

            XPRSprob prob = new XPRSprob();
            prob.AddMsgHandlerCallback(Console.Out);

            XPRSmipsolpool msp = new XPRSmipsolpool();

            msp.ProbAttach(prob);

            prob.MPSFormat = -1;
            prob.ReadProb("hpw15");

            prob.Minim("g");

            int nSols = msp.Solutions;

            if (nSols > 0)
            {
                int iSolutionId, iSolutionIdStatus;
                double dObj;
                msp.GetDblAttribProbExtreme(prob, 0, out iSolutionId, (int)XPRSattribute.Msp_SolPrb_Obj, out dObj);

                Console.WriteLine("Optimal Solution ID: " + iSolutionId);
                Console.WriteLine("Optimal Objective  : " + dObj);

                int nCols = msp.GetIntAttribSol(iSolutionId, out iSolutionIdStatus, (int)XPRSattribute.Msp_Sol_Cols);
                for (int i = 0; i < nCols; i++)
                {
                    int nValuesReturned;
                    double[] dSol = new double[1];
                    msp.GetSol(iSolutionId, out iSolutionIdStatus, dSol, i, i, out nValuesReturned);
                    Console.WriteLine(i + " = " + dSol[0]);
                }
            }

            XPRS.Free();
        }
    }
}

Back to examples browserPrevious exampleNext example