COIN-OR::LEMON - Graph Library

source: lemon-0.x/demo/lp_demo.cc @ 1577:15098fb5275c

Last change on this file since 1577:15098fb5275c was 1577:15098fb5275c, checked in by athos, 15 years ago

Documentation (lp_demo,lp_maxflow) and slight changes (rest).

File size: 4.5 KB
Line 
1/* -*- C++ -*-
2 * demo/graph_to_eps.cc - Part of LEMON, a generic C++ optimization library
3 *
4 * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
5 * (Egervary Research Group on Combinatorial Optimization, EGRES).
6 *
7 * Permission to use, modify and distribute this software is granted
8 * provided that this copyright notice appears in all copies. For
9 * precise terms see the accompanying LICENSE file.
10 *
11 * This software is provided "AS IS" with no warranty of any kind,
12 * express or implied, and with no claim as to its suitability for any
13 * purpose.
14 *
15 */
16
17/// \ingroup demos
18/// \file
19/// \brief A program demonstrating the LEMON LP solver interface
20///
21/// This program is a simple application of the LEMON LP solver
22/// interface: we formulate a linear programming (LP) problem and then
23/// solve it using the underlying solver (GLPK or CPLEX for
24/// example). For the detailed documentation of the LEMON LP solver
25/// interface read \ref lemon::LpSolverBase "this".
26
27#ifdef HAVE_CONFIG_H
28#include <config.h>
29#endif
30
31#include <iostream>
32
33
34#ifdef HAVE_GLPK
35#include <lemon/lp_glpk.h>
36#elif HAVE_CPLEX
37#include <lemon/lp_cplex.h>
38#endif
39
40using namespace lemon;
41
42
43
44#ifdef HAVE_GLPK
45typedef LpGlpk LpDefault;
46const char default_solver_name[]="GLPK";
47#elif HAVE_CPLEX
48typedef LpCplex LpDefault;
49const char default_solver_name[]="CPLEX";
50#endif
51
52int main()
53{     
54 //The following example is taken from the documentation of the GLPK library.
55 //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
56
57  //A default solver is taken
58  LpDefault lp;
59  typedef LpDefault::Row Row;
60  typedef LpDefault::Col Col;
61 
62
63  std::cout<<"A program demonstrating the LEMON LP solver interface"<<std::endl;
64  std::cout<<"Solver used: "<<default_solver_name<<std::endl;
65
66  //This will be a maximization
67  lp.max();
68
69  //We add coloumns (variables) to our problem
70  Col x1 = lp.addCol();
71  Col x2 = lp.addCol();
72  Col x3 = lp.addCol();
73
74  //Constraints
75  lp.addRow(x1+x2+x3 <=100); 
76  lp.addRow(10*x1+4*x2+5*x3<=600); 
77  lp.addRow(2*x1+2*x2+6*x3<=300); 
78  //Nonnegativity of the variables
79  lp.colLowerBound(x1, 0);
80  lp.colLowerBound(x2, 0);
81  lp.colLowerBound(x3, 0);
82  //Objective function
83  lp.setObj(10*x1+6*x2+4*x3);
84 
85  //Call the routine of the underlying LP solver
86  lp.solve();
87
88  //Print results
89  if (lp.primalStatus()==LpSolverBase::OPTIMAL){
90    std::cout<<"Optimal solution found!"<<std::endl;
91    printf("optimum value = %g; x1 = %g; x2 = %g; x3 = %g\n",
92           lp.primalValue(),
93           lp.primal(x1), lp.primal(x2), lp.primal(x3));
94  }
95  else{
96    std::cout<<"Optimal solution not found!"<<std::endl;
97  }
98
99  //End of LEMON style code
100
101  //Here comes the same problem written in C using GLPK API routines
102
103//   LPX *lp;
104//       int ia[1+1000], ja[1+1000];
105//       double ar[1+1000], Z, x1, x2, x3;
106// s1:   lp = lpx_create_prob();
107// s2:   lpx_set_prob_name(lp, "sample");
108// s3:   lpx_set_obj_dir(lp, LPX_MAX);
109// s4:   lpx_add_rows(lp, 3);
110// s5:   lpx_set_row_name(lp, 1, "p");
111// s6:   lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
112// s7:   lpx_set_row_name(lp, 2, "q");
113// s8:   lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
114// s9:   lpx_set_row_name(lp, 3, "r");
115// s10:  lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
116// s11:  lpx_add_cols(lp, 3);
117// s12:  lpx_set_col_name(lp, 1, "x1");
118// s13:  lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
119// s14:  lpx_set_obj_coef(lp, 1, 10.0);
120// s15:  lpx_set_col_name(lp, 2, "x2");
121// s16:  lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
122// s17:  lpx_set_obj_coef(lp, 2, 6.0);
123// s18:  lpx_set_col_name(lp, 3, "x3");
124// s19:  lpx_set_col_bnds(lp, 3, LPX_LO, 0.0, 0.0);
125// s20:  lpx_set_obj_coef(lp, 3, 4.0);
126// s21:  ia[1] = 1, ja[1] = 1, ar[1] =  1.0; /* a[1,1] =  1 */
127// s22:  ia[2] = 1, ja[2] = 2, ar[2] =  1.0; /* a[1,2] =  1 */
128// s23:  ia[3] = 1, ja[3] = 3, ar[3] =  1.0; /* a[1,3] =  1 */
129// s24:  ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
130// s25:  ia[5] = 3, ja[5] = 1, ar[5] =  2.0; /* a[3,1] =  2 */
131// s26:  ia[6] = 2, ja[6] = 2, ar[6] =  4.0; /* a[2,2] =  4 */
132// s27:  ia[7] = 3, ja[7] = 2, ar[7] =  2.0; /* a[3,2] =  2 */
133// s28:  ia[8] = 2, ja[8] = 3, ar[8] =  5.0; /* a[2,3] =  5 */
134// s29:  ia[9] = 3, ja[9] = 3, ar[9] =  6.0; /* a[3,3] =  6 */
135// s30:  lpx_load_matrix(lp, 9, ia, ja, ar);
136// s31:  lpx_simplex(lp);
137// s32:  Z = lpx_get_obj_val(lp);
138// s33:  x1 = lpx_get_col_prim(lp, 1);
139// s34:  x2 = lpx_get_col_prim(lp, 2);
140// s35:  x3 = lpx_get_col_prim(lp, 3);
141// s36:  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
142// s37:  lpx_delete_prob(lp);
143//       return 0;
144
145  return 0;
146}
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