package examples;

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

* File: Transport.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.

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

*/

import ilog.cplex.*;

import ilog.concert.*;

public class Transport {

public static void main(String[] args) {

if (args.length < 1) {

System.err.println("Usage: java Transport <type>");

System.err.println(" type = 0 -> convex piecewise linear model");

System.err.println(" type = 1 -> concave piecewise linear model");

return;

}

try {

IloCplex cplex = new IloCplex();

int nbDemand = 4;

int nbSupply = 3;

double[] supply = { 1000.0, 850.0, 1250.0 };

double[] demand = { 900.0, 1200.0, 600.0, 400.0 };

IloNumVar[][] x = new IloNumVar[nbSupply][];

IloNumVar[][] y = new IloNumVar[nbSupply][];

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

x[i] = cplex.numVarArray(nbDemand, 0., Double.MAX_VALUE);

y[i] = cplex.numVarArray(nbDemand, 0., Double.MAX_VALUE);

}

for (int i = 0; i < nbSupply; i++) // supply must meet demand

cplex.addEq(cplex.sum(x[i]), supply[i]);

for (int j = 0; j < nbDemand; j++) { // demand must meet supply

IloLinearNumExpr v = cplex.linearNumExpr();

for (int i = 0; i < nbSupply; i++)

v.addTerm(1., x[i][j]);

cplex.addEq(v, demand[j]);

}

double[] points;

double[] slopes;

if (args[0].charAt(0) == '0') { // convex case

points = new double[] { 200.0, 400.0 };

slopes = new double[] { 30.0, 80.0, 130.0 };

} else { // concave case

points = new double[] { 200.0, 400.0 };

slopes = new double[] { 120.0, 80.0, 50.0 };

}

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

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

// 定义中间变量y[i][j]，使用piecewiseLinear进行分段线性函数的处理

cplex.addEq(y[i][j], cplex.piecewiseLinear(x[i][j], points, slopes, 0.0, 0.0));

}

}

// 添加构造好的分段线性目标函数

IloLinearNumExpr expr = cplex.linearNumExpr();

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

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

expr.addTerm(y[i][j], 1.);

}

}

cplex.addMinimize(expr);

if (cplex.solve()) {

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

System.out.println(" - Solution: ");

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

System.out.print(" " + i + ": ");

for (int j = 0; j < nbDemand; ++j)

System.out.print("" + cplex.getValue(x[i][j]) + "\t");

System.out.println();

}

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

}

cplex.end();

} catch (IloException exc) {

System.out.println(exc);

}

}

}