source: lemon-0.x/lemon/mip_glpk.cc @ 2253:1645f6cc9667

/* -*- C++ -*-
 *
 * This file is a part of LEMON, a generic C++ optimization library
 *
 * Copyright (C) 2003-2006
 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
 * (Egervary Research Group on Combinatorial Optimization, EGRES).
 *
 * Permission to use, modify and distribute this software is granted
 * provided that this copyright notice appears in all copies. For
 * precise terms see the accompanying LICENSE file.
 *
 * This software is provided "AS IS" with no warranty of any kind,
 * express or implied, and with no claim as to its suitability for any
 * purpose.
 *
 */

///\file
///\brief Implementation of the LEMON-GLPK mip solver interface.

#include <lemon/mip_glpk.h>

namespace lemon {
  
  MipGlpk::MipGlpk() {
    lpx_set_class(lp,LPX_MIP);
  }

  void MipGlpk::_colType(int i, MipGlpk::ColTypes col_type){
    switch (col_type){
      case LEMON_INTEGER:
        lpx_set_col_kind(lp,i,LPX_IV);
        break;
      case REAL:
        lpx_set_col_kind(lp,i,LPX_CV);
        break;
    default:;
        //FIXME problem
    }
  }
  
  MipGlpk::ColTypes MipGlpk::_colType(int i){
    switch (lpx_get_col_kind(lp,i)){
    case LPX_IV:
      return LEMON_INTEGER;//Or binary
    case LPX_CV:
      return REAL;
    default:
      return REAL;//Error!
    }
    
  }
  
  LpGlpk::SolveExitStatus MipGlpk::_solve(){
    int result = lpx_simplex(lp);
    //
    if (lpx_get_status(lp)==LPX_OPT){
      //Maybe we could try the routine lpx_intopt(lp), a revised
      //version of lpx_integer
      result = lpx_integer(lp);
      switch (result){
      case LPX_E_OK:
        return SOLVED;
      default:
        return UNSOLVED;
      }
      
    }
    return UNSOLVED;
  }


  LpGlpk::SolutionStatus MipGlpk::_getMipStatus(){

    if (lpx_get_status(lp)==LPX_OPT){
      //Meg kell nezni: ha az LP is infinite, akkor ez is, ha az is
      //infeasible, akkor ez is, de ez lehet maskepp is infeasible.
      int stat=  lpx_mip_status(lp);
      
      switch (stat) {
      case LPX_I_UNDEF://Undefined (no solve has been run yet)
        return UNDEFINED;
      case LPX_I_NOFEAS://There is no feasible integral solution
        return INFEASIBLE;
        //     case LPX_UNBND://Unbounded
        //       return INFINITE;
      case LPX_I_FEAS://Feasible
        return FEASIBLE;
      case LPX_I_OPT://Feasible
        return OPTIMAL;
      default:
      return UNDEFINED; //to avoid gcc warning
      //FIXME error
      }
    }
    else 
      return UNDEFINED; //Maybe we could refine this: what does the LP
                        //relaxation look like
      
  }  

  MipGlpk::Value MipGlpk::_getPrimal(int i){
    return lpx_mip_col_val(lp,i);
  }
  
  MipGlpk::Value MipGlpk::_getPrimalValue(){
    return lpx_mip_obj_val(lp);
  }
} //END OF NAMESPACE LEMON