Bug fixes.
3 * This file is a part of LEMON, a generic C++ optimization library
5 * Copyright (C) 2003-2007
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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.
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
21 /// \brief A program demonstrating the LEMON LP solver interface
23 /// This program is a simple application of the LEMON LP solver
24 /// interface: we formulate a linear programming (LP) problem and then
25 /// solve it using the underlying solver (GLPK or CPLEX for
26 /// example). For the detailed documentation of the LEMON LP solver
27 /// interface read \ref lemon::LpSolverBase "this".
29 /// \include lp_demo.cc
35 using namespace lemon;
39 //The following example is taken from the documentation of the GLPK library.
40 //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
42 //A default solver is taken
48 std::cout<<"A program demonstrating the LEMON LP solver interface"<<std::endl;
49 std::cout<<"Solver used: "<<default_solver_name<<std::endl;
51 //This will be a maximization
54 //We add coloumns (variables) to our problem
60 lp.addRow(x1+x2+x3 <=100);
61 lp.addRow(10*x1+4*x2+5*x3<=600);
62 lp.addRow(2*x1+2*x2+6*x3<=300);
63 //Nonnegativity of the variables
64 lp.colLowerBound(x1, 0);
65 lp.colLowerBound(x2, 0);
66 lp.colLowerBound(x3, 0);
68 lp.obj(10*x1+6*x2+4*x3);
70 //Call the routine of the underlying LP solver
74 if (lp.primalStatus()==LpSolverBase::OPTIMAL){
75 std::cout<<"Optimal solution found!"<<std::endl;
76 printf("optimum value = %g; x1 = %g; x2 = %g; x3 = %g\n",
78 lp.primal(x1), lp.primal(x2), lp.primal(x3));
81 std::cout<<"Optimal solution not found!"<<std::endl;
84 //End of LEMON style code
86 //Here comes the same problem written in C using GLPK API routines
89 // int ia[1+1000], ja[1+1000];
90 // double ar[1+1000], Z, x1, x2, x3;
91 // s1: lp = lpx_create_prob();
92 // s2: lpx_set_prob_name(lp, "sample");
93 // s3: lpx_set_obj_dir(lp, LPX_MAX);
94 // s4: lpx_add_rows(lp, 3);
95 // s5: lpx_set_row_name(lp, 1, "p");
96 // s6: lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
97 // s7: lpx_set_row_name(lp, 2, "q");
98 // s8: lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
99 // s9: lpx_set_row_name(lp, 3, "r");
100 // s10: lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
101 // s11: lpx_add_cols(lp, 3);
102 // s12: lpx_set_col_name(lp, 1, "x1");
103 // s13: lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
104 // s14: lpx_set_obj_coef(lp, 1, 10.0);
105 // s15: lpx_set_col_name(lp, 2, "x2");
106 // s16: lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
107 // s17: lpx_set_obj_coef(lp, 2, 6.0);
108 // s18: lpx_set_col_name(lp, 3, "x3");
109 // s19: lpx_set_col_bnds(lp, 3, LPX_LO, 0.0, 0.0);
110 // s20: lpx_set_obj_coef(lp, 3, 4.0);
111 // s21: ia[1] = 1, ja[1] = 1, ar[1] = 1.0; /* a[1,1] = 1 */
112 // s22: ia[2] = 1, ja[2] = 2, ar[2] = 1.0; /* a[1,2] = 1 */
113 // s23: ia[3] = 1, ja[3] = 3, ar[3] = 1.0; /* a[1,3] = 1 */
114 // s24: ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
115 // s25: ia[5] = 3, ja[5] = 1, ar[5] = 2.0; /* a[3,1] = 2 */
116 // s26: ia[6] = 2, ja[6] = 2, ar[6] = 4.0; /* a[2,2] = 4 */
117 // s27: ia[7] = 3, ja[7] = 2, ar[7] = 2.0; /* a[3,2] = 2 */
118 // s28: ia[8] = 2, ja[8] = 3, ar[8] = 5.0; /* a[2,3] = 5 */
119 // s29: ia[9] = 3, ja[9] = 3, ar[9] = 6.0; /* a[3,3] = 6 */
120 // s30: lpx_load_matrix(lp, 9, ia, ja, ar);
121 // s31: lpx_simplex(lp);
122 // s32: Z = lpx_get_obj_val(lp);
123 // s33: x1 = lpx_get_col_prim(lp, 1);
124 // s34: x2 = lpx_get_col_prim(lp, 2);
125 // s35: x3 = lpx_get_col_prim(lp, 3);
126 // s36: printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
127 // s37: lpx_delete_prob(lp);