COIN-OR::LEMON - Graph Library

source: lemon-0.x/demo/lp_demo.cc @ 1523:144ab0e4b09c

Last change on this file since 1523:144ab0e4b09c was 1513:b2a79aaa6867, checked in by athos, 15 years ago

Minor changes

File size: 3.4 KB
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1#ifdef HAVE_CONFIG_H
2#include <config.h>
3#endif
4
5#include <iostream>
6
7
8#ifdef HAVE_GLPK
9#include <lemon/lp_glpk.h>
10#elif HAVE_CPLEX
11#include <lemon/lp_cplex.h>
12#endif
13
14using namespace lemon;
15
16#ifdef HAVE_GLPK
17typedef LpGlpk LpDefault;
18#elif HAVE_CPLEX
19typedef LpCplex LpDefault;
20#endif
21
22int main()
23{     
24 //The following example is taken from the documentation of the GLPK library.
25 //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
26  LpDefault lp;
27  typedef LpDefault::Row Row;
28  typedef LpDefault::Col Col;
29 
30
31  //This will be a maximization
32  lp.max();
33
34  //We add coloumns (variables) to our problem
35  Col x1 = lp.addCol();
36  Col x2 = lp.addCol();
37  Col x3 = lp.addCol();
38
39  //One solution
40  //   Row p = lp.addRow();
41  //   Row q = lp.addRow();
42  //   Row r = lp.addRow();
43  //   lp.setRow(p,x1+x2+x3 <=100); 
44  //   lp.setRow(q,10*x1+4*x2+5*x3<=600); 
45  //   lp.setRow(r,2*x1+2*x2+6*x3<=300); 
46
47  //A more elegant one
48  //Constraints
49  lp.addRow(x1+x2+x3 <=100); 
50  lp.addRow(10*x1+4*x2+5*x3<=600); 
51  lp.addRow(2*x1+2*x2+6*x3<=300); 
52  //Nonnegativity of the variables
53  lp.colLowerBound(x1, 0);
54  lp.colLowerBound(x2, 0);
55  lp.colLowerBound(x3, 0);
56  //Objective function
57  lp.setObj(10*x1+6*x2+4*x3);
58 
59  //Call the routine of the underlying LP solver
60  lp.solve();
61
62  //Print results
63  if (lp.primalStatus()==LpSolverBase::OPTIMAL){
64    printf("Z = %g; x1 = %g; x2 = %g; x3 = %g\n",
65           lp.primalValue(),
66           lp.primal(x1), lp.primal(x2), lp.primal(x3));
67  }
68  else{
69    std::cout<<"Optimal solution not found!"<<std::endl;
70  }
71
72
73  //Here comes the same problem written in C using GLPK API routines
74
75//   LPX *lp;
76//       int ia[1+1000], ja[1+1000];
77//       double ar[1+1000], Z, x1, x2, x3;
78// s1:   lp = lpx_create_prob();
79// s2:   lpx_set_prob_name(lp, "sample");
80// s3:   lpx_set_obj_dir(lp, LPX_MAX);
81// s4:   lpx_add_rows(lp, 3);
82// s5:   lpx_set_row_name(lp, 1, "p");
83// s6:   lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
84// s7:   lpx_set_row_name(lp, 2, "q");
85// s8:   lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
86// s9:   lpx_set_row_name(lp, 3, "r");
87// s10:  lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
88// s11:  lpx_add_cols(lp, 3);
89// s12:  lpx_set_col_name(lp, 1, "x1");
90// s13:  lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
91// s14:  lpx_set_obj_coef(lp, 1, 10.0);
92// s15:  lpx_set_col_name(lp, 2, "x2");
93// s16:  lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
94// s17:  lpx_set_obj_coef(lp, 2, 6.0);
95// s18:  lpx_set_col_name(lp, 3, "x3");
96// s19:  lpx_set_col_bnds(lp, 3, LPX_LO, 0.0, 0.0);
97// s20:  lpx_set_obj_coef(lp, 3, 4.0);
98// s21:  ia[1] = 1, ja[1] = 1, ar[1] =  1.0; /* a[1,1] =  1 */
99// s22:  ia[2] = 1, ja[2] = 2, ar[2] =  1.0; /* a[1,2] =  1 */
100// s23:  ia[3] = 1, ja[3] = 3, ar[3] =  1.0; /* a[1,3] =  1 */
101// s24:  ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
102// s25:  ia[5] = 3, ja[5] = 1, ar[5] =  2.0; /* a[3,1] =  2 */
103// s26:  ia[6] = 2, ja[6] = 2, ar[6] =  4.0; /* a[2,2] =  4 */
104// s27:  ia[7] = 3, ja[7] = 2, ar[7] =  2.0; /* a[3,2] =  2 */
105// s28:  ia[8] = 2, ja[8] = 3, ar[8] =  5.0; /* a[2,3] =  5 */
106// s29:  ia[9] = 3, ja[9] = 3, ar[9] =  6.0; /* a[3,3] =  6 */
107// s30:  lpx_load_matrix(lp, 9, ia, ja, ar);
108// s31:  lpx_simplex(lp);
109// s32:  Z = lpx_get_obj_val(lp);
110// s33:  x1 = lpx_get_col_prim(lp, 1);
111// s34:  x2 = lpx_get_col_prim(lp, 2);
112// s35:  x3 = lpx_get_col_prim(lp, 3);
113// s36:  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
114// s37:  lpx_delete_prob(lp);
115//       return 0;
116
117  return 0;
118}
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