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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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*
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* This file is a part of LEMON, a generic C++ optimization library.
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*
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* Copyright (C) 2003-2008
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* Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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* (Egervary Research Group on Combinatorial Optimization, EGRES).
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*
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* Permission to use, modify and distribute this software is granted
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* provided that this copyright notice appears in all copies. For
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* precise terms see the accompanying LICENSE file.
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*
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* This software is provided "AS IS" with no warranty of any kind,
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* express or implied, and with no claim as to its suitability for any
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* purpose.
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*
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*/
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///\file
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///\brief Implementation of the LEMON-CPLEX mip solver interface.
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#include <lemon/mip_cplex.h>
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extern "C" {
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#include <ilcplex/cplex.h>
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}
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namespace lemon {
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MipCplex::MipCplex() {
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//This is unnecessary: setting integrality constraints on
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//variables will set this, too
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///\todo The constant CPXPROB_MIP is
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///called CPXPROB_MILP in later versions
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#if CPX_VERSION < 800
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CPXchgprobtype( env, lp, CPXPROB_MIP);
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#else
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CPXchgprobtype( env, lp, CPXPROB_MILP);
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#endif
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}
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void MipCplex::_colType(int i, MipCplex::ColTypes col_type){
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// Note If a variable is to be changed to binary, a call to CPXchgbds
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// should also be made to change the bounds to 0 and 1.
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int indices[1];
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indices[0]=i;
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char ctype[1];
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switch (col_type){
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case INT:
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ctype[0]=CPX_INTEGER;//'I'
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break;
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case REAL:
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ctype[0]=CPX_CONTINUOUS ;//'C'
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break;
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default:;
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//FIXME problem
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}
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CPXchgctype (env, lp, 1, indices, ctype);
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}
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MipCplex::ColTypes MipCplex::_colType(int i) const {
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char ctype[1];
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CPXgetctype (env, lp, ctype, i, i);
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switch (ctype[0]){
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case CPX_INTEGER:
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return INT;
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case CPX_CONTINUOUS:
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return REAL;
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default:
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return REAL;//Error!
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}
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}
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LpCplex::SolveExitStatus MipCplex::_solve(){
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status = CPXmipopt (env, lp);
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if (status==0)
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return SOLVED;
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else
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return UNSOLVED;
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}
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LpCplex::SolutionStatus MipCplex::_getMipStatus() const {
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int stat = CPXgetstat(env, lp);
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//Fortunately, MIP statuses did not change for cplex 8.0
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switch (stat)
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{
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case CPXMIP_OPTIMAL:
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// Optimal integer solution has been found.
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case CPXMIP_OPTIMAL_TOL:
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// Optimal soluton with the tolerance defined by epgap or epagap has
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// been found.
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return OPTIMAL;
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//This also exists in later issues
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// case CPXMIP_UNBOUNDED:
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//return INFINITE;
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case CPXMIP_INFEASIBLE:
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return INFEASIBLE;
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default:
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return UNDEFINED;
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}
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//Unboundedness not treated well: the following is from cplex 9.0 doc
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// About Unboundedness
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// The treatment of models that are unbounded involves a few
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// subtleties. Specifically, a declaration of unboundedness means that
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// ILOG CPLEX has determined that the model has an unbounded
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// ray. Given any feasible solution x with objective z, a multiple of
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// the unbounded ray can be added to x to give a feasible solution
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// with objective z-1 (or z+1 for maximization models). Thus, if a
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// feasible solution exists, then the optimal objective is
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// unbounded. Note that ILOG CPLEX has not necessarily concluded that
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// a feasible solution exists. Users can call the routine CPXsolninfo
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// to determine whether ILOG CPLEX has also concluded that the model
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// has a feasible solution.
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}
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MipCplex::Value MipCplex::_getPrimal(int i) const {
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Value x;
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CPXgetmipx(env, lp, &x, i, i);
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return x;
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}
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MipCplex::Value MipCplex::_getPrimalValue() const {
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Value objval;
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CPXgetmipobjval(env, lp, &objval);
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return objval;
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}
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} //END OF NAMESPACE LEMON
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