COIN-OR::LEMON - Graph Library

source: lemon-tutorial/demo/mip_demo.cc

Last change on this file was 54:e99a7fb6bff5, checked in by Peter Kovacs <kpeter@…>, 11 years ago

Port and rework LP demo files from SVN -r3524

File size: 2.0 KB
Line 
1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2010
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19///\file
20///\brief Demo program for the MIP solver interface.
21///
22/// This demo program shows how the LEMON MIP solver interface can be used.
23/// A simple mixed integer programming (MIP) problem is formulated and solved
24/// using the default MIP solver (e.g. GLPK).
25///
26/// \include mip_demo.cc
27
28#include <iostream>
29#include <lemon/lp.h>
30
31using namespace lemon;
32
33int main()
34{
35  // Create an instance of the default MIP solver class
36  // (it will represent an "empty" problem at first)
37  Mip mip;
38
39  // Add two columns (variables) to the problem
40  Mip::Col x1 = mip.addCol();
41  Mip::Col x2 = mip.addCol();
42
43  // Add rows (constraints) to the problem
44  mip.addRow(x1 - 5 <= x2);
45  mip.addRow(0 <= 2 * x1 + x2 <= 25);
46 
47  // Set lower and upper bounds for the columns (variables)
48  mip.colLowerBound(x1, 0);
49  mip.colUpperBound(x2, 10);
50 
51  // Set the type of the columns
52  mip.colType(x1, Mip::INTEGER);
53  mip.colType(x2, Mip::REAL);
54 
55  // Specify the objective function
56  mip.max();
57  mip.obj(5 * x1 + 3 * x2);
58 
59  // Solve the problem using the underlying MIP solver
60  mip.solve();
61
62  // Print the results
63  if (mip.type() == Mip::OPTIMAL) {
64    std::cout << "Objective function value: " << mip.solValue() << std::endl;
65    std::cout << "x1 = " << mip.sol(x1) << std::endl;
66    std::cout << "x2 = " << mip.sol(x2) << std::endl;
67  } else {
68    std::cout << "Optimal solution not found." << std::endl;
69  }
70
71  return 0;
72}
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