私はC++でcplexを使用しています。最近、私は次の例を見ていました。それから私は populate 関数に混乱しています。値渡しですよね？しかし、populate 関数を実行した後、main 関数で作成されたモデルが更新されたのはなぜですか? それはまだ空のモデルであるべきではありませんか？
// -------------------------------------------------------------- -*- C++ -*-
// File: ilolpex1.cpp
// Version 12.5
// --------------------------------------------------------------------------
// Licensed Materials - Property of IBM
// 5725-A06 5725-A29 5724-Y48 5724-Y49 5724-Y54 5724-Y55 5655-Y21
// Copyright IBM Corporation 2000, 2012. All Rights Reserved.
//
// US Government Users Restricted Rights - Use, duplication or
// disclosure restricted by GSA ADP Schedule Contract with
// IBM Corp.
// --------------------------------------------------------------------------
//
// ilolpex1.cpp - Entering and optimizing a problem. Demonstrates different
// methods for creating a problem. The user has to choose the method
// on the command line:
//
// ilolpex1 -r generates the problem by adding rows
// ilolpex1 -c generates the problem by adding columns
// ilolpex1 -n generates the problem by adding a list of coefficients
#include <ilcplex/ilocplex.h>
ILOSTLBEGIN
static void
usage (const char *progname),
populatebyrow (IloModel model, IloNumVarArray var, IloRangeArray con),
populatebycolumn (IloModel model, IloNumVarArray var, IloRangeArray con),
populatebynonzero (IloModel model, IloNumVarArray var, IloRangeArray con);
int
main (int argc, char **argv)
{
IloEnv env;
try {
IloModel model(env);
if (( argc != 2 ) ||
( argv[1][0] != '-' ) ||
( strchr ("rcn", argv[1][1]) == NULL ) ) {
usage (argv[0]);
throw(-1);
}
IloNumVarArray var(env);
IloRangeArray con(env);
switch (argv[1][1]) {
case 'r':
populatebyrow (model, var, con);
break;
case 'c':
populatebycolumn (model, var, con);
break;
case 'n':
populatebynonzero (model, var, con);
break;
}
IloCplex cplex(model);
cplex.exportModel("lpex1.lp");
// Optimize the problem and obtain solution.
if ( !cplex.solve() ) {
env.error() << "Failed to optimize LP" << endl;
throw(-1);
}
IloNumArray vals(env);
env.out() << "Solution status = " << cplex.getStatus() << endl;
env.out() << "Solution value = " << cplex.getObjValue() << endl;
cplex.getValues(vals, var);
env.out() << "Values = " << vals << endl;
cplex.getSlacks(vals, con);
env.out() << "Slacks = " << vals << endl;
cplex.getDuals(vals, con);
env.out() << "Duals = " << vals << endl;
cplex.getReducedCosts(vals, var);
env.out() << "Reduced Costs = " << vals << endl;
}
catch (IloException& e) {
cerr << "Concert exception caught: " << e << endl;
}
catch (...) {
cerr << "Unknown exception caught" << endl;
}
env.end();
return 0;
} // END main
static void usage (const char *progname)
{
cerr << "Usage: " << progname << " -X" << endl;
cerr << " where X is one of the following options:" << endl;
cerr << " r generate problem by row" << endl;
cerr << " c generate problem by column" << endl;
cerr << " n generate problem by nonzero" << endl;
cerr << " Exiting..." << endl;
} // END usage
// To populate by row, we first create the variables, and then use them to
// create the range constraints and objective.
static void
populatebyrow (IloModel model, IloNumVarArray x, IloRangeArray c)
{
IloEnv env = model.getEnv();
x.add(IloNumVar(env, 0.0, 40.0));
x.add(IloNumVar(env));
x.add(IloNumVar(env));
model.add(IloMaximize(env, x[0] + 2 * x[1] + 3 * x[2]));
c.add( - x[0] + x[1] + x[2] <= 20);
c.add( x[0] - 3 * x[1] + x[2] <= 30);
x[0].setName("x1");
x[1].setName("x2");
x[2].setName("x3");
c[0].setName("c1");
c[1].setName("c2");
model.add(c);
} // END populatebyrow
// To populate by column, we first create the range constraints and the
// objective, and then create the variables and add them to the ranges and
// objective using column expressions.
static void
populatebycolumn (IloModel model, IloNumVarArray x, IloRangeArray c)
{
IloEnv env = model.getEnv();
IloObjective obj = IloMaximize(env);
c.add(IloRange(env, -IloInfinity, 20.0, "c1"));
c.add(IloRange(env, -IloInfinity, 30.0, "c2"));
x.add(IloNumVar(obj(1.0) + c[0](-1.0) + c[1]( 1.0), 0.0, 40.0));
x.add(IloNumVar(obj(2.0) + c[0]( 1.0) + c[1](-3.0)));
x.add(IloNumVar(obj(3.0) + c[0]( 1.0) + c[1]( 1.0)));
x[0].setName("x1");
x[1].setName("x2");
x[2].setName("x3");
model.add(obj);
model.add(c);
} // END populatebycolumn
// To populate by nonzero, we first create the rows, then create the
// columns, and then change the nonzeros of the matrix 1 at a time.
static void
populatebynonzero (IloModel model, IloNumVarArray x, IloRangeArray c)
{
IloEnv env = model.getEnv();
IloObjective obj = IloMaximize(env);
c.add(IloRange(env, -IloInfinity, 20.0));
c.add(IloRange(env, -IloInfinity, 30.0));
x.add(IloNumVar(env, 0.0, 40.0));
x.add(IloNumVar(env));
x.add(IloNumVar(env));
obj.setLinearCoef(x[0], 1.0);
obj.setLinearCoef(x[1], 2.0);
obj.setLinearCoef(x[2], 3.0);
c[0].setLinearCoef(x[0], -1.0);
c[0].setLinearCoef(x[1], 1.0);
c[0].setLinearCoef(x[2], 1.0);
c[1].setLinearCoef(x[0], 1.0);
c[1].setLinearCoef(x[1], -3.0);
c[1].setLinearCoef(x[2], 1.0);
c[0].setName("c1");
c[1].setName("c2");
x[0].setName("x1");
x[1].setName("x2");
x[2].setName("x3");
model.add(obj);
model.add(c);
} // END populatebynonzero