src/demo/lp_demo.cc
author marci
Sat, 23 Apr 2005 16:59:49 +0000
changeset 1383 79b68a337f9f
parent 1362 b4330c52caeb
child 1387 37d1b20cd9ef
permissions -rw-r--r--
A new implementation of UndirGraphWrapper, accordig to the undirected concepts
     1 #include <iostream>
     2 
     3 
     4 #ifdef HAVE_GLPK
     5 #include <lemon/lp_glpk.h>
     6 #elif HAVE_CPLEX
     7 #include <lemon/lp_cplex.h>
     8 #endif
     9 
    10 using namespace lemon;
    11 
    12 #ifdef HAVE_GLPK
    13 typedef LpGlpk LpDefault;
    14 #elif HAVE_CPLEX
    15 typedef LpCplex LpDefault;
    16 #endif
    17 
    18 int main()
    19 {     
    20  //The following example is taken from the documentation of the GLPK library.
    21  //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
    22   LpDefault lp;
    23   typedef LpDefault::Row Row;
    24   typedef LpDefault::Col Col;
    25 
    26   lp.max();
    27 
    28   Col x1 = lp.addCol();
    29   Col x2 = lp.addCol();
    30   Col x3 = lp.addCol();
    31 
    32   //One solution
    33   //   Row p = lp.addRow();
    34   //   Row q = lp.addRow();
    35   //   Row r = lp.addRow();
    36   //   lp.setRow(p,x1+x2+x3 <=100);  
    37   //   lp.setRow(q,10*x1+4*x2+5*x3<=600);  
    38   //   lp.setRow(r,2*x1+2*x2+6*x3<=300);  
    39 
    40   //A more elegant one
    41   //Constraints
    42   lp.addRow(x1+x2+x3 <=100);  
    43   lp.addRow(10*x1+4*x2+5*x3<=600);  
    44   lp.addRow(2*x1+2*x2+6*x3<=300);  
    45   //Nonnegativity of the variables
    46   lp.colLowerBound(x1, 0);
    47   lp.colLowerBound(x2, 0);
    48   lp.colLowerBound(x3, 0);
    49   //Objective function
    50   lp.setObj(10*x1+6*x2+4*x3);
    51   
    52   lp.solve();
    53 
    54   if (lp.primalStatus()==LpSolverBase::OPTIMAL){
    55     printf("Z = %g; x1 = %g; x2 = %g; x3 = %g\n", 
    56 	   lp.primalValue(), 
    57 	   lp.primal(x1), lp.primal(x2), lp.primal(x3));
    58   }
    59   else{
    60     std::cout<<"Optimal solution not found!"<<std::endl;
    61   }
    62 
    63 
    64   //Here comes the same problem written in C using GLPK API routines
    65 
    66 //   LPX *lp;
    67 //       int ia[1+1000], ja[1+1000];
    68 //       double ar[1+1000], Z, x1, x2, x3;
    69 // s1:   lp = lpx_create_prob();
    70 // s2:   lpx_set_prob_name(lp, "sample");
    71 // s3:   lpx_set_obj_dir(lp, LPX_MAX);
    72 // s4:   lpx_add_rows(lp, 3);
    73 // s5:   lpx_set_row_name(lp, 1, "p");
    74 // s6:   lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
    75 // s7:   lpx_set_row_name(lp, 2, "q");
    76 // s8:   lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
    77 // s9:   lpx_set_row_name(lp, 3, "r");
    78 // s10:  lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
    79 // s11:  lpx_add_cols(lp, 3);
    80 // s12:  lpx_set_col_name(lp, 1, "x1");
    81 // s13:  lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
    82 // s14:  lpx_set_obj_coef(lp, 1, 10.0);
    83 // s15:  lpx_set_col_name(lp, 2, "x2");
    84 // s16:  lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
    85 // s17:  lpx_set_obj_coef(lp, 2, 6.0);
    86 // s18:  lpx_set_col_name(lp, 3, "x3");
    87 // s19:  lpx_set_col_bnds(lp, 3, LPX_LO, 0.0, 0.0);
    88 // s20:  lpx_set_obj_coef(lp, 3, 4.0);
    89 // s21:  ia[1] = 1, ja[1] = 1, ar[1] =  1.0; /* a[1,1] =  1 */
    90 // s22:  ia[2] = 1, ja[2] = 2, ar[2] =  1.0; /* a[1,2] =  1 */
    91 // s23:  ia[3] = 1, ja[3] = 3, ar[3] =  1.0; /* a[1,3] =  1 */
    92 // s24:  ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
    93 // s25:  ia[5] = 3, ja[5] = 1, ar[5] =  2.0; /* a[3,1] =  2 */
    94 // s26:  ia[6] = 2, ja[6] = 2, ar[6] =  4.0; /* a[2,2] =  4 */
    95 // s27:  ia[7] = 3, ja[7] = 2, ar[7] =  2.0; /* a[3,2] =  2 */
    96 // s28:  ia[8] = 2, ja[8] = 3, ar[8] =  5.0; /* a[2,3] =  5 */
    97 // s29:  ia[9] = 3, ja[9] = 3, ar[9] =  6.0; /* a[3,3] =  6 */
    98 // s30:  lpx_load_matrix(lp, 9, ia, ja, ar);
    99 // s31:  lpx_simplex(lp);
   100 // s32:  Z = lpx_get_obj_val(lp);
   101 // s33:  x1 = lpx_get_col_prim(lp, 1);
   102 // s34:  x2 = lpx_get_col_prim(lp, 2);
   103 // s35:  x3 = lpx_get_col_prim(lp, 3);
   104 // s36:  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
   105 // s37:  lpx_delete_prob(lp);
   106 //       return 0;
   107 
   108   return 0;
   109 }