COIN-OR::LEMON - Graph Library

source: lemon-0.x/src/work/athos/lp/lp_sample.cc @ 1318:88edb143a87a

Last change on this file since 1318:88edb143a87a was 1318:88edb143a87a, checked in by athos, 15 years ago

Sample file completed: works correctly and the code is very beautiful. I love LEMON.

File size: 2.9 KB
Line 
1#include <iostream>
2#include <lemon/lp_glpk.h>
3using namespace lemon;
4
5int main()
6{     
7 //The following example is taken from the documentation of the GLPK library.
8 //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
9  LpGlpk lp;
10  typedef LpGlpk::Row Row;
11  typedef LpGlpk::Col Col;
12
13  lp.max();
14
15  Col x1 = lp.addCol();
16  Col x2 = lp.addCol();
17  Col x3 = lp.addCol();
18
19  //One solution
20  //   Row p = lp.addRow();
21  //   Row q = lp.addRow();
22  //   Row r = lp.addRow();
23  //   lp.setRow(p,x1+x2+x3 <=100); 
24  //   lp.setRow(q,10*x1+4*x2+5*x3<=600); 
25  //   lp.setRow(r,2*x1+2*x2+6*x3<=300); 
26
27  //A more elegant one
28  //Constraints
29  lp.addRow(x1+x2+x3 <=100); 
30  lp.addRow(10*x1+4*x2+5*x3<=600); 
31  lp.addRow(2*x1+2*x2+6*x3<=300); 
32  //Nonnegativity of the variables
33  lp.colLowerBound(x1, 0);
34  lp.colLowerBound(x2, 0);
35  lp.colLowerBound(x3, 0);
36  //Objective function
37  lp.setObj(10*x1+6*x2+4*x3);
38 
39  lp.solve();
40 
41  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n",
42         lp.primalValue(),
43         lp.primal(x1), lp.primal(x2), lp.primal(x3));
44
45  //Here comes the same problem written in C using GLPK API routines
46
47//   LPX *lp;
48//       int ia[1+1000], ja[1+1000];
49//       double ar[1+1000], Z, x1, x2, x3;
50// s1:   lp = lpx_create_prob();
51// s2:   lpx_set_prob_name(lp, "sample");
52// s3:   lpx_set_obj_dir(lp, LPX_MAX);
53// s4:   lpx_add_rows(lp, 3);
54// s5:   lpx_set_row_name(lp, 1, "p");
55// s6:   lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
56// s7:   lpx_set_row_name(lp, 2, "q");
57// s8:   lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
58// s9:   lpx_set_row_name(lp, 3, "r");
59// s10:  lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
60// s11:  lpx_add_cols(lp, 3);
61// s12:  lpx_set_col_name(lp, 1, "x1");
62// s13:  lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
63// s14:  lpx_set_obj_coef(lp, 1, 10.0);
64// s15:  lpx_set_col_name(lp, 2, "x2");
65// s16:  lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
66// s17:  lpx_set_obj_coef(lp, 2, 6.0);
67// s18:  lpx_set_col_name(lp, 3, "x3");
68// s19:  lpx_set_col_bnds(lp, 3, LPX_LO, 0.0, 0.0);
69// s20:  lpx_set_obj_coef(lp, 3, 4.0);
70// s21:  ia[1] = 1, ja[1] = 1, ar[1] =  1.0; /* a[1,1] =  1 */
71// s22:  ia[2] = 1, ja[2] = 2, ar[2] =  1.0; /* a[1,2] =  1 */
72// s23:  ia[3] = 1, ja[3] = 3, ar[3] =  1.0; /* a[1,3] =  1 */
73// s24:  ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
74// s25:  ia[5] = 3, ja[5] = 1, ar[5] =  2.0; /* a[3,1] =  2 */
75// s26:  ia[6] = 2, ja[6] = 2, ar[6] =  4.0; /* a[2,2] =  4 */
76// s27:  ia[7] = 3, ja[7] = 2, ar[7] =  2.0; /* a[3,2] =  2 */
77// s28:  ia[8] = 2, ja[8] = 3, ar[8] =  5.0; /* a[2,3] =  5 */
78// s29:  ia[9] = 3, ja[9] = 3, ar[9] =  6.0; /* a[3,3] =  6 */
79// s30:  lpx_load_matrix(lp, 9, ia, ja, ar);
80// s31:  lpx_simplex(lp);
81// s32:  Z = lpx_get_obj_val(lp);
82// s33:  x1 = lpx_get_col_prim(lp, 1);
83// s34:  x2 = lpx_get_col_prim(lp, 2);
84// s35:  x3 = lpx_get_col_prim(lp, 3);
85// s36:  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
86// s37:  lpx_delete_prob(lp);
87//       return 0;
88
89  return 0;
90}
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