# HG changeset patch
# User Peter Kovacs <kpeter@inf.elte.hu>
# Date 1267406784 -3600
# Node ID e99a7fb6bff536620b05d23509457ced4ec88ba5
# Parent  0f695eac7e0769c94cfb1ce6ce83d8cc8d57e1ff
Port and rework LP demo files from SVN -r3524

diff -r 0f695eac7e07 -r e99a7fb6bff5 demo/hello_lemon.cc
--- a/demo/hello_lemon.cc	Sun Feb 28 19:38:57 2010 +0100
+++ b/demo/hello_lemon.cc	Mon Mar 01 02:26:24 2010 +0100
@@ -20,6 +20,7 @@
 ///\brief Simple "Hello World!" program for LEMON.
 ///
 /// Simple "Hello World!" program for LEMON.
+///
 /// \include hello_lemon.cc
 
 #include <iostream>
diff -r 0f695eac7e07 -r e99a7fb6bff5 demo/lp_demo.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demo/lp_demo.cc	Mon Mar 01 02:26:24 2010 +0100
@@ -0,0 +1,68 @@
+/* -*- mode: C++; indent-tabs-mode: nil; -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library.
+ *
+ * Copyright (C) 2003-2010
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+///\file
+///\brief Demo program for the LP solver interface.
+///
+/// This demo program shows how the LEMON LP solver interface can be used.
+/// A simple linear programming (LP) problem is formulated and solved using
+/// the default LP solver (e.g. GLPK).
+///
+/// \include lp_demo.cc
+
+#include <iostream>
+#include <lemon/lp.h>
+
+using namespace lemon;
+
+int main()
+{
+  // Create an instance of the default LP solver class
+  // (it will represent an "empty" problem at first)
+  Lp lp;
+
+  // Add two columns (variables) to the problem
+  Lp::Col x1 = lp.addCol();
+  Lp::Col x2 = lp.addCol();
+
+  // Add rows (constraints) to the problem
+  lp.addRow(x1 - 5 <= x2);
+  lp.addRow(0 <= 2 * x1 + x2 <= 25);
+  
+  // Set lower and upper bounds for the columns (variables)
+  lp.colLowerBound(x1, 0);
+  lp.colUpperBound(x2, 10);
+  
+  // Specify the objective function
+  lp.max();
+  lp.obj(5 * x1 + 3 * x2);
+  
+  // Solve the problem using the underlying LP solver
+  lp.solve();
+
+  // Print the results
+  if (lp.primalType() == Lp::OPTIMAL) {
+    std::cout << "Objective function value: " << lp.primal() << std::endl;
+    std::cout << "x1 = " << lp.primal(x1) << std::endl;
+    std::cout << "x2 = " << lp.primal(x2) << std::endl;
+  } else {
+    std::cout << "Optimal solution not found." << std::endl;
+  }
+
+  return 0;
+}
diff -r 0f695eac7e07 -r e99a7fb6bff5 demo/lp_maxflow_demo.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demo/lp_maxflow_demo.cc	Mon Mar 01 02:26:24 2010 +0100
@@ -0,0 +1,105 @@
+/* -*- mode: C++; indent-tabs-mode: nil; -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library.
+ *
+ * Copyright (C) 2003-2010
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+///\file
+///\brief Demo program that solves maximum flow problems using the LP interface
+///
+/// This demo program shows how to solve the maximum flow problem using
+/// the LEMON LP solver interface. We would like to lay the emphasis on the
+/// simplicity of the way one can formulate LP constraints that arise in graph
+/// theory using LEMON.
+///
+/// \include lp_maxflow_demo.cc
+
+#include <iostream>
+#include <lemon/smart_graph.h>
+#include <lemon/lgf_reader.h>
+#include <lemon/lp.h>
+
+using namespace lemon;
+
+template <typename GR, typename CAP>
+double maxFlow(const GR &g, const CAP &capacity,
+               typename GR::Node source, typename GR::Node target)
+{
+  TEMPLATE_DIGRAPH_TYPEDEFS(GR);
+  
+  // Create an instance of the default LP solver
+  Lp lp;
+
+  // Add a column to the problem for each arc
+  typename GR::template ArcMap<Lp::Col> f(g);
+  lp.addColSet(f);
+
+  // Capacity constraints
+  for (ArcIt a(g); a != INVALID; ++a) {
+    lp.colLowerBound(f[a], 0);
+    lp.colUpperBound(f[a], capacity[a]);
+  }
+
+  // Flow conservation constraints
+  for (NodeIt n(g); n != INVALID; ++n) {
+    if (n == source || n == target) continue;
+    Lp::Expr e;
+    for (OutArcIt a(g, n); a != INVALID; ++a) e += f[a];
+    for (InArcIt a(g, n); a != INVALID; ++a) e -= f[a];
+    lp.addRow(e == 0);
+  }
+
+  // Objective function
+  Lp::Expr o;
+  for (OutArcIt a(g, source); a != INVALID; ++a) o += f[a];
+  for (InArcIt a(g, source); a != INVALID; ++a) o -= f[a];
+  lp.max();
+  lp.obj(o);
+
+  // Solve the LP problem
+  lp.solve();
+
+  return lp.primal();
+}
+
+
+int main(int argc, char *argv[])
+{
+  // Check the arguments
+  if (argc < 2) {
+    std::cerr << "Usage:" << std::endl;
+    std::cerr << "  lp_maxflow_demo <input_file>" << std::endl;
+    std::cerr << "The given input file has to contain a maximum flow\n"
+              << "problem in LGF format (like 'maxflow.lgf')."
+              << std::endl;
+    return 0;
+  }
+  
+  // Read the input file
+  SmartDigraph g;
+  SmartDigraph::ArcMap<double> cap(g);
+  SmartDigraph::Node s, t;
+
+  digraphReader(g, argv[1])
+    .arcMap("capacity", cap)
+    .node("source", s)
+    .node("target", t)
+    .run();
+
+  // Solve the problem and print the result
+  std::cout << "Max flow value: " << maxFlow(g, cap, s, t) << std::endl;
+ 
+  return 0;
+}
diff -r 0f695eac7e07 -r e99a7fb6bff5 demo/maxflow.lgf
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demo/maxflow.lgf	Mon Mar 01 02:26:24 2010 +0100
@@ -0,0 +1,34 @@
+@nodes
+label
+0
+1
+2
+3
+4
+5
+6
+7
+8
+9
+@arcs
+    capacity
+0 1 20
+0 2 0
+1 1 3
+1 2 8
+1 3 8
+2 5 5
+3 2 5
+3 5 5
+3 6 5
+4 3 3
+5 7 3
+5 6 10
+5 8 10
+6 8 8
+8 9 20
+8 1 5
+9 5 5
+@attributes
+source 1
+target 8
diff -r 0f695eac7e07 -r e99a7fb6bff5 demo/mip_demo.cc
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/demo/mip_demo.cc	Mon Mar 01 02:26:24 2010 +0100
@@ -0,0 +1,72 @@
+/* -*- mode: C++; indent-tabs-mode: nil; -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library.
+ *
+ * Copyright (C) 2003-2010
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+///\file
+///\brief Demo program for the MIP solver interface.
+///
+/// This demo program shows how the LEMON MIP solver interface can be used.
+/// A simple mixed integer programming (MIP) problem is formulated and solved
+/// using the default MIP solver (e.g. GLPK).
+///
+/// \include mip_demo.cc
+
+#include <iostream>
+#include <lemon/lp.h>
+
+using namespace lemon;
+
+int main()
+{
+  // Create an instance of the default MIP solver class
+  // (it will represent an "empty" problem at first)
+  Mip mip;
+
+  // Add two columns (variables) to the problem
+  Mip::Col x1 = mip.addCol();
+  Mip::Col x2 = mip.addCol();
+
+  // Add rows (constraints) to the problem
+  mip.addRow(x1 - 5 <= x2);
+  mip.addRow(0 <= 2 * x1 + x2 <= 25);
+  
+  // Set lower and upper bounds for the columns (variables)
+  mip.colLowerBound(x1, 0);
+  mip.colUpperBound(x2, 10);
+  
+  // Set the type of the columns
+  mip.colType(x1, Mip::INTEGER);
+  mip.colType(x2, Mip::REAL);
+  
+  // Specify the objective function
+  mip.max();
+  mip.obj(5 * x1 + 3 * x2);
+  
+  // Solve the problem using the underlying MIP solver
+  mip.solve();
+
+  // Print the results
+  if (mip.type() == Mip::OPTIMAL) {
+    std::cout << "Objective function value: " << mip.solValue() << std::endl;
+    std::cout << "x1 = " << mip.sol(x1) << std::endl;
+    std::cout << "x2 = " << mip.sol(x2) << std::endl;
+  } else {
+    std::cout << "Optimal solution not found." << std::endl;
+  }
+
+  return 0;
+}