athos@1577: /* -*- C++ -*-
athos@1577:  * demo/graph_to_eps.cc - Part of LEMON, a generic C++ optimization library
athos@1577:  *
athos@1577:  * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
athos@1577:  * (Egervary Research Group on Combinatorial Optimization, EGRES).
athos@1577:  *
athos@1577:  * Permission to use, modify and distribute this software is granted
athos@1577:  * provided that this copyright notice appears in all copies. For
athos@1577:  * precise terms see the accompanying LICENSE file.
athos@1577:  *
athos@1577:  * This software is provided "AS IS" with no warranty of any kind,
athos@1577:  * express or implied, and with no claim as to its suitability for any
athos@1577:  * purpose.
athos@1577:  *
athos@1577:  */
athos@1577: 
athos@1577: /// \ingroup demos
athos@1577: /// \file
athos@1577: /// \brief A program demonstrating the LEMON LP solver interface
athos@1577: ///
athos@1577: /// This program is a simple application of the LEMON LP solver
athos@1577: /// interface: we formulate a linear programming (LP) problem and then
athos@1577: /// solve it using the underlying solver (GLPK or CPLEX for
athos@1577: /// example). For the detailed documentation of the LEMON LP solver
athos@1577: /// interface read \ref lemon::LpSolverBase "this".
athos@1577: 
alpar@1610: #include <lemon/lp.h>
ladanyi@1387: 
alpar@1362: #include <iostream>
alpar@1381: 
alpar@1362: using namespace lemon;
alpar@1362: 
alpar@1362: int main()
alpar@1362: {     
alpar@1362:  //The following example is taken from the documentation of the GLPK library.
alpar@1362:  //See it in the GLPK reference manual and among the GLPK sample files (sample.c)
athos@1530: 
athos@1530:   //A default solver is taken
alpar@1610:   Lp lp;
alpar@1610:   typedef Lp::Row Row;
alpar@1610:   typedef Lp::Col Col;
athos@1513:   
alpar@1362: 
athos@1577:   std::cout<<"A program demonstrating the LEMON LP solver interface"<<std::endl; 
athos@1577:   std::cout<<"Solver used: "<<default_solver_name<<std::endl;
athos@1577: 
athos@1513:   //This will be a maximization
alpar@1362:   lp.max();
alpar@1362: 
athos@1513:   //We add coloumns (variables) to our problem
alpar@1362:   Col x1 = lp.addCol();
alpar@1362:   Col x2 = lp.addCol();
alpar@1362:   Col x3 = lp.addCol();
alpar@1362: 
alpar@1362:   //Constraints
alpar@1362:   lp.addRow(x1+x2+x3 <=100);  
alpar@1362:   lp.addRow(10*x1+4*x2+5*x3<=600);  
alpar@1362:   lp.addRow(2*x1+2*x2+6*x3<=300);  
alpar@1362:   //Nonnegativity of the variables
alpar@1362:   lp.colLowerBound(x1, 0);
alpar@1362:   lp.colLowerBound(x2, 0);
alpar@1362:   lp.colLowerBound(x3, 0);
alpar@1362:   //Objective function
alpar@1362:   lp.setObj(10*x1+6*x2+4*x3);
alpar@1362:   
athos@1513:   //Call the routine of the underlying LP solver
alpar@1362:   lp.solve();
alpar@1362: 
athos@1513:   //Print results
alpar@1362:   if (lp.primalStatus()==LpSolverBase::OPTIMAL){
athos@1577:     std::cout<<"Optimal solution found!"<<std::endl;
athos@1577:     printf("optimum value = %g; x1 = %g; x2 = %g; x3 = %g\n", 
alpar@1362: 	   lp.primalValue(), 
alpar@1362: 	   lp.primal(x1), lp.primal(x2), lp.primal(x3));
alpar@1362:   }
alpar@1362:   else{
alpar@1362:     std::cout<<"Optimal solution not found!"<<std::endl;
alpar@1362:   }
alpar@1362: 
athos@1530:   //End of LEMON style code
alpar@1362: 
alpar@1362:   //Here comes the same problem written in C using GLPK API routines
alpar@1362: 
alpar@1362: //   LPX *lp;
alpar@1362: //       int ia[1+1000], ja[1+1000];
alpar@1362: //       double ar[1+1000], Z, x1, x2, x3;
alpar@1362: // s1:   lp = lpx_create_prob();
alpar@1362: // s2:   lpx_set_prob_name(lp, "sample");
alpar@1362: // s3:   lpx_set_obj_dir(lp, LPX_MAX);
alpar@1362: // s4:   lpx_add_rows(lp, 3);
alpar@1362: // s5:   lpx_set_row_name(lp, 1, "p");
alpar@1362: // s6:   lpx_set_row_bnds(lp, 1, LPX_UP, 0.0, 100.0);
alpar@1362: // s7:   lpx_set_row_name(lp, 2, "q");
alpar@1362: // s8:   lpx_set_row_bnds(lp, 2, LPX_UP, 0.0, 600.0);
alpar@1362: // s9:   lpx_set_row_name(lp, 3, "r");
alpar@1362: // s10:  lpx_set_row_bnds(lp, 3, LPX_UP, 0.0, 300.0);
alpar@1362: // s11:  lpx_add_cols(lp, 3);
alpar@1362: // s12:  lpx_set_col_name(lp, 1, "x1");
alpar@1362: // s13:  lpx_set_col_bnds(lp, 1, LPX_LO, 0.0, 0.0);
alpar@1362: // s14:  lpx_set_obj_coef(lp, 1, 10.0);
alpar@1362: // s15:  lpx_set_col_name(lp, 2, "x2");
alpar@1362: // s16:  lpx_set_col_bnds(lp, 2, LPX_LO, 0.0, 0.0);
alpar@1362: // s17:  lpx_set_obj_coef(lp, 2, 6.0);
alpar@1362: // s18:  lpx_set_col_name(lp, 3, "x3");
alpar@1362: // s19:  lpx_set_col_bnds(lp, 3, LPX_LO, 0.0, 0.0);
alpar@1362: // s20:  lpx_set_obj_coef(lp, 3, 4.0);
alpar@1362: // s21:  ia[1] = 1, ja[1] = 1, ar[1] =  1.0; /* a[1,1] =  1 */
alpar@1362: // s22:  ia[2] = 1, ja[2] = 2, ar[2] =  1.0; /* a[1,2] =  1 */
alpar@1362: // s23:  ia[3] = 1, ja[3] = 3, ar[3] =  1.0; /* a[1,3] =  1 */
alpar@1362: // s24:  ia[4] = 2, ja[4] = 1, ar[4] = 10.0; /* a[2,1] = 10 */
alpar@1362: // s25:  ia[5] = 3, ja[5] = 1, ar[5] =  2.0; /* a[3,1] =  2 */
alpar@1362: // s26:  ia[6] = 2, ja[6] = 2, ar[6] =  4.0; /* a[2,2] =  4 */
alpar@1362: // s27:  ia[7] = 3, ja[7] = 2, ar[7] =  2.0; /* a[3,2] =  2 */
alpar@1362: // s28:  ia[8] = 2, ja[8] = 3, ar[8] =  5.0; /* a[2,3] =  5 */
alpar@1362: // s29:  ia[9] = 3, ja[9] = 3, ar[9] =  6.0; /* a[3,3] =  6 */
alpar@1362: // s30:  lpx_load_matrix(lp, 9, ia, ja, ar);
alpar@1362: // s31:  lpx_simplex(lp);
alpar@1362: // s32:  Z = lpx_get_obj_val(lp);
alpar@1362: // s33:  x1 = lpx_get_col_prim(lp, 1);
alpar@1362: // s34:  x2 = lpx_get_col_prim(lp, 2);
alpar@1362: // s35:  x3 = lpx_get_col_prim(lp, 3);
alpar@1362: // s36:  printf("\nZ = %g; x1 = %g; x2 = %g; x3 = %g\n", Z, x1, x2, x3);
alpar@1362: // s37:  lpx_delete_prob(lp);
alpar@1362: //       return 0;
alpar@1362: 
alpar@1362:   return 0;
alpar@1362: }