/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Copyright (C) 2003-2009

 * 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 LP and MIP solver interface.

#include <lemon/glpk.h>

#include <glpk.h>

#include <lemon/assert.h>

namespace lemon {

  // GlpkBase members

  GlpkBase::GlpkBase() : LpBase() {

    lp = glp_create_prob();

    glp_create_index(lp);

  }

  GlpkBase::GlpkBase(const GlpkBase &other) : LpBase() {

    lp = glp_create_prob();

    glp_copy_prob(lp, other.lp, GLP_ON);

    glp_create_index(lp);

    rows = other.rows;

    cols = other.cols;

  }

  GlpkBase::~GlpkBase() {

    glp_delete_prob(lp);

  }

  int GlpkBase::_addCol() {

    int i = glp_add_cols(lp, 1);

    glp_set_col_bnds(lp, i, GLP_FR, 0.0, 0.0);

    return i;

  }

  int GlpkBase::_addRow() {

    int i = glp_add_rows(lp, 1);

    glp_set_row_bnds(lp, i, GLP_FR, 0.0, 0.0);

    return i;

  }

  void GlpkBase::_eraseCol(int i) {

    int ca[2];

    ca[1] = i;

    glp_del_cols(lp, 1, ca);

  }

  void GlpkBase::_eraseRow(int i) {

    int ra[2];

    ra[1] = i;

    glp_del_rows(lp, 1, ra);

  }

  void GlpkBase::_eraseColId(int i) {

    cols.eraseIndex(i);

    cols.shiftIndices(i);

  }

  void GlpkBase::_eraseRowId(int i) {

    rows.eraseIndex(i);

    rows.shiftIndices(i);

  }

  void GlpkBase::_getColName(int c, std::string& name) const {

    const char *str = glp_get_col_name(lp, c);

    if (str) name = str;

    else name.clear();

  }

  void GlpkBase::_setColName(int c, const std::string & name) {

    glp_set_col_name(lp, c, const_cast<char*>(name.c_str()));

  }

  int GlpkBase::_colByName(const std::string& name) const {

    int k = glp_find_col(lp, const_cast<char*>(name.c_str()));

    return k > 0 ? k : -1;

  }

  void GlpkBase::_getRowName(int r, std::string& name) const {

    const char *str = glp_get_row_name(lp, r);

    if (str) name = str;

    else name.clear();

  }

  void GlpkBase::_setRowName(int r, const std::string & name) {

    glp_set_row_name(lp, r, const_cast<char*>(name.c_str()));

  }

  int GlpkBase::_rowByName(const std::string& name) const {

    int k = glp_find_row(lp, const_cast<char*>(name.c_str()));

    return k > 0 ? k : -1;

  }

  void GlpkBase::_setRowCoeffs(int i, ExprIterator b, ExprIterator e) {

    std::vector<int> indexes;

    std::vector<Value> values;

    indexes.push_back(0);

    values.push_back(0);

    for(ExprIterator it = b; it != e; ++it) {

      indexes.push_back(it->first);

      values.push_back(it->second);

    }

    glp_set_mat_row(lp, i, values.size() - 1,

                    &indexes.front(), &values.front());

  }

  void GlpkBase::_getRowCoeffs(int ix, InsertIterator b) const {

    int length = glp_get_mat_row(lp, ix, 0, 0);

    std::vector<int> indexes(length + 1);

    std::vector<Value> values(length + 1);

    glp_get_mat_row(lp, ix, &indexes.front(), &values.front());

    for (int i = 1; i <= length; ++i) {

      *b = std::make_pair(indexes[i], values[i]);

      ++b;

    }

  }

  void GlpkBase::_setColCoeffs(int ix, ExprIterator b,

                                     ExprIterator e) {

    std::vector<int> indexes;

    std::vector<Value> values;

    indexes.push_back(0);

    values.push_back(0);

    for(ExprIterator it = b; it != e; ++it) {

      indexes.push_back(it->first);

      values.push_back(it->second);

    }

    glp_set_mat_col(lp, ix, values.size() - 1,

                    &indexes.front(), &values.front());

  }

  void GlpkBase::_getColCoeffs(int ix, InsertIterator b) const {

    int length = glp_get_mat_col(lp, ix, 0, 0);

    std::vector<int> indexes(length + 1);

    std::vector<Value> values(length + 1);

    glp_get_mat_col(lp, ix, &indexes.front(), &values.front());

    for (int i = 1; i  <= length; ++i) {

      *b = std::make_pair(indexes[i], values[i]);

      ++b;

    }

  }

  void GlpkBase::_setCoeff(int ix, int jx, Value value) {

    if (glp_get_num_cols(lp) < glp_get_num_rows(lp)) {

      int length = glp_get_mat_row(lp, ix, 0, 0);

      std::vector<int> indexes(length + 2);

      std::vector<Value> values(length + 2);

      glp_get_mat_row(lp, ix, &indexes.front(), &values.front());

      //The following code does not suppose that the elements of the

      //array indexes are sorted

      bool found = false;

      for (int i = 1; i  <= length; ++i) {

        if (indexes[i] == jx) {

          found = true;

          values[i] = value;

          break;

        }

      }

      if (!found) {

        ++length;

        indexes[length] = jx;

        values[length] = value;

      }

      glp_set_mat_row(lp, ix, length, &indexes.front(), &values.front());

    } else {

      int length = glp_get_mat_col(lp, jx, 0, 0);

      std::vector<int> indexes(length + 2);

      std::vector<Value> values(length + 2);

      glp_get_mat_col(lp, jx, &indexes.front(), &values.front());

      //The following code does not suppose that the elements of the

      //array indexes are sorted

      bool found = false;

      for (int i = 1; i <= length; ++i) {

        if (indexes[i] == ix) {

          found = true;

          values[i] = value;

          break;

        }

      }

      if (!found) {

        ++length;

        indexes[length] = ix;

        values[length] = value;

      }

      glp_set_mat_col(lp, jx, length, &indexes.front(), &values.front());

    }

  }

  GlpkBase::Value GlpkBase::_getCoeff(int ix, int jx) const {

    int length = glp_get_mat_row(lp, ix, 0, 0);

    std::vector<int> indexes(length + 1);

    std::vector<Value> values(length + 1);

    glp_get_mat_row(lp, ix, &indexes.front(), &values.front());

    for (int i = 1; i  <= length; ++i) {

      if (indexes[i] == jx) {

        return values[i];

      }

    }

    return 0;

  }

  void GlpkBase::_setColLowerBound(int i, Value lo) {

    LEMON_ASSERT(lo != INF, "Invalid bound");

    int b = glp_get_col_type(lp, i);

    double up = glp_get_col_ub(lp, i);

    if (lo == -INF) {

      switch (b) {

      case GLP_FR:

      case GLP_LO:

        glp_set_col_bnds(lp, i, GLP_FR, lo, up);

        break;

      case GLP_UP:

        break;

      case GLP_DB:

      case GLP_FX:

        glp_set_col_bnds(lp, i, GLP_UP, lo, up);

        break;

      default:

        break;

      }

    } else {

      switch (b) {

      case GLP_FR:

      case GLP_LO:

        glp_set_col_bnds(lp, i, GLP_LO, lo, up);

        break;

      case GLP_UP:

      case GLP_DB:

      case GLP_FX:

        if (lo == up)

          glp_set_col_bnds(lp, i, GLP_FX, lo, up);

        else

          glp_set_col_bnds(lp, i, GLP_DB, lo, up);

        break;

      default:

        break;

      }

    }

  }

  GlpkBase::Value GlpkBase::_getColLowerBound(int i) const {

    int b = glp_get_col_type(lp, i);

    switch (b) {

    case GLP_LO:

    case GLP_DB:

    case GLP_FX:

      return glp_get_col_lb(lp, i);

    default:

      return -INF;

    }

  }

  void GlpkBase::_setColUpperBound(int i, Value up) {

    LEMON_ASSERT(up != -INF, "Invalid bound");

    int b = glp_get_col_type(lp, i);

    double lo = glp_get_col_lb(lp, i);

    if (up == INF) {

      switch (b) {

      case GLP_FR:

      case GLP_LO:

        break;

      case GLP_UP:

        glp_set_col_bnds(lp, i, GLP_FR, lo, up);

        break;

      case GLP_DB:

      case GLP_FX:

        glp_set_col_bnds(lp, i, GLP_LO, lo, up);

        break;

      default:

        break;

      }

    } else {

      switch (b) {

      case GLP_FR:

        glp_set_col_bnds(lp, i, GLP_UP, lo, up);

        break;

      case GLP_UP:

        glp_set_col_bnds(lp, i, GLP_UP, lo, up);

        break;

      case GLP_LO:

      case GLP_DB:

      case GLP_FX:

        if (lo == up)

          glp_set_col_bnds(lp, i, GLP_FX, lo, up);

        else

          glp_set_col_bnds(lp, i, GLP_DB, lo, up);

        break;

      default:

        break;

      }

    }

  }

  GlpkBase::Value GlpkBase::_getColUpperBound(int i) const {

    int b = glp_get_col_type(lp, i);

      switch (b) {

      case GLP_UP:

      case GLP_DB:

      case GLP_FX:

        return glp_get_col_ub(lp, i);

      default:

        return INF;

      }

  }

  void GlpkBase::_setRowLowerBound(int i, Value lo) {

    LEMON_ASSERT(lo != INF, "Invalid bound");

    int b = glp_get_row_type(lp, i);

    double up = glp_get_row_ub(lp, i);

    if (lo == -INF) {

      switch (b) {

      case GLP_FR:

      case GLP_LO:

        glp_set_row_bnds(lp, i, GLP_FR, lo, up);

        break;

      case GLP_UP:

        break;

      case GLP_DB:

      case GLP_FX:

        glp_set_row_bnds(lp, i, GLP_UP, lo, up);

        break;

      default:

        break;

      }

    } else {

      switch (b) {

      case GLP_FR:

      case GLP_LO:

        glp_set_row_bnds(lp, i, GLP_LO, lo, up);

        break;

      case GLP_UP:

      case GLP_DB:

      case GLP_FX:

        if (lo == up)

          glp_set_row_bnds(lp, i, GLP_FX, lo, up);

        else

          glp_set_row_bnds(lp, i, GLP_DB, lo, up);

        break;

      default:

        break;

      }

    }

  }

  GlpkBase::Value GlpkBase::_getRowLowerBound(int i) const {

    int b = glp_get_row_type(lp, i);

    switch (b) {

    case GLP_LO:

    case GLP_DB:

    case GLP_FX:

      return glp_get_row_lb(lp, i);

    default:

      return -INF;

    }

  }

  void GlpkBase::_setRowUpperBound(int i, Value up) {

    LEMON_ASSERT(up != -INF, "Invalid bound");

    int b = glp_get_row_type(lp, i);

    double lo = glp_get_row_lb(lp, i);

    if (up == INF) {

      switch (b) {

      case GLP_FR:

      case GLP_LO:

        break;

      case GLP_UP:

        glp_set_row_bnds(lp, i, GLP_FR, lo, up);

        break;

      case GLP_DB:

      case GLP_FX:

        glp_set_row_bnds(lp, i, GLP_LO, lo, up);

        break;

      default:

        break;

      }

    } else {

      switch (b) {

      case GLP_FR:

        glp_set_row_bnds(lp, i, GLP_UP, lo, up);

        break;

      case GLP_UP:

        glp_set_row_bnds(lp, i, GLP_UP, lo, up);

        break;

      case GLP_LO:

      case GLP_DB:

      case GLP_FX:

        if (lo == up)

          glp_set_row_bnds(lp, i, GLP_FX, lo, up);

        else

          glp_set_row_bnds(lp, i, GLP_DB, lo, up);

        break;

      default:

        break;

      }

    }

  }

  GlpkBase::Value GlpkBase::_getRowUpperBound(int i) const {

    int b = glp_get_row_type(lp, i);

    switch (b) {

    case GLP_UP:

    case GLP_DB:

    case GLP_FX:

      return glp_get_row_ub(lp, i);

    default:

      return INF;

    }

  }

  void GlpkBase::_setObjCoeffs(ExprIterator b, ExprIterator e) {

    for (int i = 1; i <= glp_get_num_cols(lp); ++i) {

      glp_set_obj_coef(lp, i, 0.0);

    }

    for (ExprIterator it = b; it != e; ++it) {

      glp_set_obj_coef(lp, it->first, it->second);

    }

  }

  void GlpkBase::_getObjCoeffs(InsertIterator b) const {

    for (int i = 1; i <= glp_get_num_cols(lp); ++i) {

      Value val = glp_get_obj_coef(lp, i);

      if (val != 0.0) {

        *b = std::make_pair(i, val);

        ++b;

      }

    }

  }

  void GlpkBase::_setObjCoeff(int i, Value obj_coef) {

    //i = 0 means the constant term (shift)

    glp_set_obj_coef(lp, i, obj_coef);

  }

  GlpkBase::Value GlpkBase::_getObjCoeff(int i) const {

    //i = 0 means the constant term (shift)

    return glp_get_obj_coef(lp, i);

  }

  void GlpkBase::_setSense(GlpkBase::Sense sense) {

    switch (sense) {

    case MIN:

      glp_set_obj_dir(lp, GLP_MIN);

      break;

    case MAX:

      glp_set_obj_dir(lp, GLP_MAX);

      break;

    }

  }

  GlpkBase::Sense GlpkBase::_getSense() const {

    switch(glp_get_obj_dir(lp)) {

    case GLP_MIN:

      return MIN;

    case GLP_MAX:

      return MAX;

    default:

      LEMON_ASSERT(false, "Wrong sense");

      return GlpkBase::Sense();

    }

  }

  void GlpkBase::_clear() {

    glp_erase_prob(lp);

    rows.clear();

    cols.clear();

  }

  void GlpkBase::freeEnv() {

    glp_free_env();

  }

  GlpkBase::FreeEnvHelper GlpkBase::freeEnvHelper;

  // GlpkLp members

  GlpkLp::GlpkLp()

    : LpBase(), LpSolver(), GlpkBase() {

    messageLevel(MESSAGE_NO_OUTPUT);

  }

  GlpkLp::GlpkLp(const GlpkLp& other)

    : LpBase(other), LpSolver(other), GlpkBase(other) {

    messageLevel(MESSAGE_NO_OUTPUT);

  }

  GlpkLp* GlpkLp::newSolver() const { return new GlpkLp; }

  GlpkLp* GlpkLp::cloneSolver() const { return new GlpkLp(*this); }

  const char* GlpkLp::_solverName() const { return "GlpkLp"; }

  void GlpkLp::_clear_temporals() {

    _primal_ray.clear();

    _dual_ray.clear();

  }

  GlpkLp::SolveExitStatus GlpkLp::_solve() {

    return solvePrimal();

  }

  GlpkLp::SolveExitStatus GlpkLp::solvePrimal() {

    _clear_temporals();

    glp_smcp smcp;

    glp_init_smcp(&smcp);

    switch (_message_level) {

    case MESSAGE_NO_OUTPUT:

      smcp.msg_lev = GLP_MSG_OFF;

      break;

    case MESSAGE_ERROR_MESSAGE:

      smcp.msg_lev = GLP_MSG_ERR;

      break;

    case MESSAGE_NORMAL_OUTPUT:

      smcp.msg_lev = GLP_MSG_ON;

      break;

    case MESSAGE_FULL_OUTPUT:

      smcp.msg_lev = GLP_MSG_ALL;

      break;

    }

    if (glp_simplex(lp, &smcp) != 0) return UNSOLVED;

    return SOLVED;

  }

  GlpkLp::SolveExitStatus GlpkLp::solveDual() {

    _clear_temporals();

    glp_smcp smcp;

    glp_init_smcp(&smcp);

    switch (_message_level) {

    case MESSAGE_NO_OUTPUT:

      smcp.msg_lev = GLP_MSG_OFF;

      break;

    case MESSAGE_ERROR_MESSAGE:

      smcp.msg_lev = GLP_MSG_ERR;

      break;

    case MESSAGE_NORMAL_OUTPUT:

      smcp.msg_lev = GLP_MSG_ON;

      break;

    case MESSAGE_FULL_OUTPUT:

      smcp.msg_lev = GLP_MSG_ALL;

      break;

    }

    smcp.meth = GLP_DUAL;

    if (glp_simplex(lp, &smcp) != 0) return UNSOLVED;

    return SOLVED;

  }

  GlpkLp::Value GlpkLp::_getPrimal(int i) const {

    return glp_get_col_prim(lp, i);

  }

  GlpkLp::Value GlpkLp::_getDual(int i) const {

    return glp_get_row_dual(lp, i);

  }

  GlpkLp::Value GlpkLp::_getPrimalValue() const {

    return glp_get_obj_val(lp);

  }

  GlpkLp::VarStatus GlpkLp::_getColStatus(int i) const {

    switch (glp_get_col_stat(lp, i)) {

    case GLP_BS:

      return BASIC;

    case GLP_UP:

      return UPPER;

    case GLP_LO:

      return LOWER;

    case GLP_NF:

      return FREE;

    case GLP_NS:

      return FIXED;

    default:

      LEMON_ASSERT(false, "Wrong column status");

      return GlpkLp::VarStatus();

    }

  }

  GlpkLp::VarStatus GlpkLp::_getRowStatus(int i) const {

    switch (glp_get_row_stat(lp, i)) {

    case GLP_BS:

      return BASIC;

    case GLP_UP:

      return UPPER;

    case GLP_LO:

      return LOWER;

    case GLP_NF:

      return FREE;

    case GLP_NS:

      return FIXED;

    default:

      LEMON_ASSERT(false, "Wrong row status");

      return GlpkLp::VarStatus();

    }

  }

  GlpkLp::Value GlpkLp::_getPrimalRay(int i) const {

    if (_primal_ray.empty()) {

      int row_num = glp_get_num_rows(lp);

      int col_num = glp_get_num_cols(lp);

      _primal_ray.resize(col_num + 1, 0.0);

      int index = glp_get_unbnd_ray(lp);

      if (index != 0) {

        // The primal ray is found in primal simplex second phase

        LEMON_ASSERT((index <= row_num ? glp_get_row_stat(lp, index) :

                      glp_get_col_stat(lp, index - row_num)) != GLP_BS,

                     "Wrong primal ray");

        bool negate = glp_get_obj_dir(lp) == GLP_MAX;

        if (index > row_num) {

          _primal_ray[index - row_num] = 1.0;

          if (glp_get_col_dual(lp, index - row_num) > 0) {

            negate = !negate;

          }

        } else {

          if (glp_get_row_dual(lp, index) > 0) {

            negate = !negate;

          }

        }

        std::vector<int> ray_indexes(row_num + 1);

        std::vector<Value> ray_values(row_num + 1);

        int ray_length = glp_eval_tab_col(lp, index, &ray_indexes.front(),

                                          &ray_values.front());

        for (int i = 1; i <= ray_length; ++i) {

          if (ray_indexes[i] > row_num) {

            _primal_ray[ray_indexes[i] - row_num] = ray_values[i];

          }

        }

        if (negate) {

          for (int i = 1; i <= col_num; ++i) {

            _primal_ray[i] = - _primal_ray[i];

          }

        }

      } else {

        for (int i = 1; i <= col_num; ++i) {

          _primal_ray[i] = glp_get_col_prim(lp, i);

        }

      }

    }

    return _primal_ray[i];

  }

  GlpkLp::Value GlpkLp::_getDualRay(int i) const {

    if (_dual_ray.empty()) {

      int row_num = glp_get_num_rows(lp);

      _dual_ray.resize(row_num + 1, 0.0);

      int index = glp_get_unbnd_ray(lp);

      if (index != 0) {

        // The dual ray is found in dual simplex second phase

        LEMON_ASSERT((index <= row_num ? glp_get_row_stat(lp, index) :

                      glp_get_col_stat(lp, index - row_num)) == GLP_BS,

                     "Wrong dual ray");

        int idx;

        bool negate = false;

        if (index > row_num) {

          idx = glp_get_col_bind(lp, index - row_num);

          if (glp_get_col_prim(lp, index - row_num) >

              glp_get_col_ub(lp, index - row_num)) {

            negate = true;

          }

        } else {

          idx = glp_get_row_bind(lp, index);

          if (glp_get_row_prim(lp, index) > glp_get_row_ub(lp, index)) {

            negate = true;

          }

        }

        _dual_ray[idx] = negate ?  - 1.0 : 1.0;

        glp_btran(lp, &_dual_ray.front());

      } else {

        double eps = 1e-7;

        // The dual ray is found in primal simplex first phase

        // We assume that the glpk minimizes the slack to get feasible solution

        for (int i = 1; i <= row_num; ++i) {

          int index = glp_get_bhead(lp, i);

          if (index <= row_num) {

            double res = glp_get_row_prim(lp, index);

            if (res > glp_get_row_ub(lp, index) + eps) {

              _dual_ray[i] = -1;

            } else if (res < glp_get_row_lb(lp, index) - eps) {

              _dual_ray[i] = 1;

            } else {

              _dual_ray[i] = 0;

            }

            _dual_ray[i] *= glp_get_rii(lp, index);

          } else {

            double res = glp_get_col_prim(lp, index - row_num);

            if (res > glp_get_col_ub(lp, index - row_num) + eps) {

              _dual_ray[i] = -1;

            } else if (res < glp_get_col_lb(lp, index - row_num) - eps) {

              _dual_ray[i] = 1;

            } else {

              _dual_ray[i] = 0;

            }

            _dual_ray[i] /= glp_get_sjj(lp, index - row_num);

          }

        }

        glp_btran(lp, &_dual_ray.front());

        for (int i = 1; i <= row_num; ++i) {

          _dual_ray[i] /= glp_get_rii(lp, i);

        }

      }

    }

    return _dual_ray[i];

  }

  GlpkLp::ProblemType GlpkLp::_getPrimalType() const {

    if (glp_get_status(lp) == GLP_OPT)

      return OPTIMAL;

    switch (glp_get_prim_stat(lp)) {

    case GLP_UNDEF:

      return UNDEFINED;

    case GLP_FEAS:

    case GLP_INFEAS:

      if (glp_get_dual_stat(lp) == GLP_NOFEAS) {

        return UNBOUNDED;

      } else {

        return UNDEFINED;

      }

    case GLP_NOFEAS:

      return INFEASIBLE;

    default:

      LEMON_ASSERT(false, "Wrong primal type");

      return  GlpkLp::ProblemType();

    }

  }

  GlpkLp::ProblemType GlpkLp::_getDualType() const {

    if (glp_get_status(lp) == GLP_OPT)

      return OPTIMAL;

    switch (glp_get_dual_stat(lp)) {

    case GLP_UNDEF:

      return UNDEFINED;

    case GLP_FEAS:

    case GLP_INFEAS:

      if (glp_get_prim_stat(lp) == GLP_NOFEAS) {

        return UNBOUNDED;

      } else {

        return UNDEFINED;

      }

    case GLP_NOFEAS:

      return INFEASIBLE;

    default:

      LEMON_ASSERT(false, "Wrong primal type");

      return  GlpkLp::ProblemType();

    }

  }

  void GlpkLp::presolver(bool b) {

    lpx_set_int_parm(lp, LPX_K_PRESOL, b ? 1 : 0);

  }

  void GlpkLp::messageLevel(MessageLevel m) {

    _message_level = m;

  }

  // GlpkMip members

  GlpkMip::GlpkMip()

    : LpBase(), MipSolver(), GlpkBase() {

    messageLevel(MESSAGE_NO_OUTPUT);

  }

  GlpkMip::GlpkMip(const GlpkMip& other)

    : LpBase(), MipSolver(), GlpkBase(other) {

    messageLevel(MESSAGE_NO_OUTPUT);

  }

  void GlpkMip::_setColType(int i, GlpkMip::ColTypes col_type) {

    switch (col_type) {

    case INTEGER:

      glp_set_col_kind(lp, i, GLP_IV);

      break;

    case REAL:

      glp_set_col_kind(lp, i, GLP_CV);

      break;

    }

  }

  GlpkMip::ColTypes GlpkMip::_getColType(int i) const {

    switch (glp_get_col_kind(lp, i)) {

    case GLP_IV:

    case GLP_BV:

      return INTEGER;

    default:

      return REAL;

    }

  }

  GlpkMip::SolveExitStatus GlpkMip::_solve() {

    glp_smcp smcp;

    glp_init_smcp(&smcp);

    switch (_message_level) {

    case MESSAGE_NO_OUTPUT:

      smcp.msg_lev = GLP_MSG_OFF;

      break;

    case MESSAGE_ERROR_MESSAGE:

      smcp.msg_lev = GLP_MSG_ERR;

      break;

    case MESSAGE_NORMAL_OUTPUT:

      smcp.msg_lev = GLP_MSG_ON;

      break;

    case MESSAGE_FULL_OUTPUT:

      smcp.msg_lev = GLP_MSG_ALL;

      break;

    }

    smcp.meth = GLP_DUAL;

    if (glp_simplex(lp, &smcp) != 0) return UNSOLVED;

    if (glp_get_status(lp) != GLP_OPT) return SOLVED;

    glp_iocp iocp;

    glp_init_iocp(&iocp);

    switch (_message_level) {

    case MESSAGE_NO_OUTPUT:

      iocp.msg_lev = GLP_MSG_OFF;

      break;

    case MESSAGE_ERROR_MESSAGE:

      iocp.msg_lev = GLP_MSG_ERR;

      break;

    case MESSAGE_NORMAL_OUTPUT:

      iocp.msg_lev = GLP_MSG_ON;

      break;

    case MESSAGE_FULL_OUTPUT:

      iocp.msg_lev = GLP_MSG_ALL;

      break;

    }

    if (glp_intopt(lp, &iocp) != 0) return UNSOLVED;

    return SOLVED;

  }

  GlpkMip::ProblemType GlpkMip::_getType() const {

    switch (glp_get_status(lp)) {

    case GLP_OPT:

      switch (glp_mip_status(lp)) {

      case GLP_UNDEF:

        return UNDEFINED;

      case GLP_NOFEAS:

        return INFEASIBLE;

      case GLP_FEAS:

        return FEASIBLE;

      case GLP_OPT:

        return OPTIMAL;

      default:

        LEMON_ASSERT(false, "Wrong problem type.");

        return GlpkMip::ProblemType();

      }

    case GLP_NOFEAS:

      return INFEASIBLE;

    case GLP_INFEAS:

    case GLP_FEAS:

      if (glp_get_dual_stat(lp) == GLP_NOFEAS) {

        return UNBOUNDED;

      } else {

        return UNDEFINED;

      }

    default:

      LEMON_ASSERT(false, "Wrong problem type.");

      return GlpkMip::ProblemType();

    }

  }

  GlpkMip::Value GlpkMip::_getSol(int i) const {

    return glp_mip_col_val(lp, i);

  }

  GlpkMip::Value GlpkMip::_getSolValue() const {

    return glp_mip_obj_val(lp);

  }

  GlpkMip* GlpkMip::newSolver() const { return new GlpkMip; }

  GlpkMip* GlpkMip::cloneSolver() const {return new GlpkMip(*this); }

  const char* GlpkMip::_solverName() const { return "GlpkMip"; }

  void GlpkMip::messageLevel(MessageLevel m) {

    _message_level = m;

  }

} //END OF NAMESPACE LEMON