package examples;

/* --------------------------------------------------------------------------

* File: LPex4.java

* Version 12.9.0

* --------------------------------------------------------------------------

* Licensed Materials - Property of IBM

* 5725-A06 5725-A29 5724-Y48 5724-Y49 5724-Y54 5724-Y55 5655-Y21

* Copyright IBM Corporation 2001, 2019. All Rights Reserved.

*

* US Government Users Restricted Rights - Use, duplication or

* disclosure restricted by GSA ADP Schedule Contract with

* IBM Corp.

* --------------------------------------------------------------------------

*

* LPex4.java - Illustrating the CPLEX callback functionality.

*

* This is a modification of LPex1.java, where we use a callback

* function to print the iteration info, rather than have CPLEX

* do it. Note that the actual LP that is solved is slightly

* different to make the output more interesting.

*/

import ilog.concert.*;

import ilog.cplex.*;

public class LPex4 {

// 会改变每一代的输出内容

// Implement the callback as an extension of class

// IloCplex.ContinuousCallback by overloading method main(). In the

// implementation use protected methods of class IloCplex.ContinuousCallback

// and its super classes, such as getNiterations64(), isFeasible(),

// getObjValue(), and getInfeasibility() used in this example.

static class MyCallback extends IloCplex.ContinuousCallback {

public void main() throws IloException {

System.out.print("Iteration " + getNiterations64() + ": ");

if (isFeasible())

System.out.println("Objective = " + getObjValue());

else

System.out.println("Infeasibility measure = " + getInfeasibility());

}

}

public static void main(String[] args) {

try {

IloCplex cplex = new IloCplex();

IloLPMatrix lp = populateByRow(cplex);

// turn off presolve to prevent it from completely solving the model

// before entering the actual LP optimizer

cplex.setParam(IloCplex.Param.Preprocessing.Presolve, false);

// turn off logging

cplex.setOut(null);

// create and instruct cplex to use callback

cplex.use(new MyCallback());

if (cplex.solve()) {

double[] x = cplex.getValues(lp);

double[] dj = cplex.getReducedCosts(lp);

double[] pi = cplex.getDuals(lp);

double[] slack = cplex.getSlacks(lp);

System.out.println("Solution status = " + cplex.getStatus());

System.out.println("Iterations = " + cplex.getNiterations64());

System.out.println("Solution value = " + cplex.getObjValue());

int nvars = x.length;

for (int j = 0; j < nvars; ++j) {

System.out.println("Variable " + j + ": Value = " + x[j] + " Reduced cost = " + dj[j]);

}

int ncons = slack.length;

for (int i = 0; i < ncons; ++i) {

System.out.println("Constraint " + i + ": Slack = " + slack[i] + " Pi = " + pi[i]);

}

}

cplex.end();

} catch (IloException e) {

System.err.println("Concert exception '" + e + "' caught");

}

}

static IloLPMatrix populateByRow(IloMPModeler model) throws IloException {

IloLPMatrix lp = model.addLPMatrix();

double[] lb = { 0.0, 0.0, 0.0 };

double[] ub = { 40.0, Double.MAX_VALUE, Double.MAX_VALUE };

IloNumVar[] x = model.numVarArray(model.columnArray(lp, 3), lb, ub);

double[] lhs = { -Double.MAX_VALUE, -Double.MAX_VALUE };

double[] rhs = { 20.0, 30.0 };

double[][] val = { { -1.0, 1.0, 1.0 }, { 1.0, -3.0, 1.0 } };

int[][] ind = { { 0, 1, 2 }, { 0, 1, 2 } };

lp.addRows(lhs, rhs, ind, val);

double[] objvals = { 1.0, 2.0, 3.0 };

model.addMaximize(model.scalProd(x, objvals));

return (lp);

}

}