COIN-OR::LEMON - Graph Library

source: lemon-0.x/lemon/mip_cplex.cc @ 2219:c263168e0964

Last change on this file since 2219:c263168e0964 was 2219:c263168e0964, checked in by athos, 13 years ago

Missing cplex files: sorry.

File size: 3.5 KB
Line 
1/* -*- C++ -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library
4 *
5 * Copyright (C) 2003-2006
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
8 *
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
12 *
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
15 * purpose.
16 *
17 */
18
19#ifndef LEMON_MIP_CPLEX_CC
20#define LEMON_MIP_CPLEX_CC
21
22///\file
23///\brief Implementation of the LEMON-CPLEX mip solver interface.
24
25#include <lemon/mip_cplex.h>
26
27namespace lemon {
28 
29  MipCplex::MipCplex() {
30    //This is unnecessary: setting integrality constraints on
31    //variables will set this, too
32
33    ///\todo The constant CPXPROB_MIP is
34    ///called CPXPROB_MILP in later versions
35    CPXchgprobtype( env,  lp, CPXPROB_MIP);
36  }
37
38  void MipCplex::_colType(int i, MipCplex::ColTypes col_type){
39
40    // Note If a variable is to be changed to binary, a call to CPXchgbds
41    // should also be made to change the bounds to 0 and 1.
42
43    int indices[1];
44    indices[0]=i;
45    char ctype[1];
46    switch (col_type){
47      case LEMON_INTEGER:
48        ctype[0]=CPX_INTEGER;//'I'
49        break;
50      case REAL:
51        ctype[0]=CPX_CONTINUOUS ;//'C'
52        break;
53    default:;
54        //FIXME problem
55    }
56    CPXchgctype (env, lp, 1, indices, ctype);
57  }
58 
59  MipCplex::ColTypes MipCplex::_colType(int i){
60   
61    char ctype[1];
62    status = CPXgetctype (env, lp, ctype, i, i);
63    switch (ctype[0]){
64
65    case CPX_INTEGER:
66      return LEMON_INTEGER;
67    case CPX_CONTINUOUS:
68      return REAL;
69    default:
70      return REAL;//Error!
71    }
72
73  }
74 
75  LpCplex::SolveExitStatus MipCplex::_solve(){
76
77    status = CPXmipopt (env, lp);
78    if (status==0)
79      return SOLVED;
80    else
81      return UNSOLVED;
82
83  }
84
85
86  LpCplex::SolutionStatus MipCplex::_getMipStatus(){
87
88    int stat = CPXgetstat(env, lp);
89
90    //Fortunately, MIP statuses did not change for cplex 8.0
91    switch (stat)
92    {
93      case CPXMIP_OPTIMAL:
94        return OPTIMAL;
95        //This also exists in later issues
96        //    case CPXMIP_UNBOUNDED:
97        //return INFINITE;
98      case CPXMIP_INFEASIBLE:
99        return INFEASIBLE;
100      default:
101        return UNDEFINED;
102    }
103    //Unboundedness not treated well: the following is from cplex 9.0 doc
104    // About Unboundedness
105
106    // The treatment of models that are unbounded involves a few
107    // subtleties. Specifically, a declaration of unboundedness means that
108    // ILOG CPLEX has determined that the model has an unbounded
109    // ray. Given any feasible solution x with objective z, a multiple of
110    // the unbounded ray can be added to x to give a feasible solution
111    // with objective z-1 (or z+1 for maximization models). Thus, if a
112    // feasible solution exists, then the optimal objective is
113    // unbounded. Note that ILOG CPLEX has not necessarily concluded that
114    // a feasible solution exists. Users can call the routine CPXsolninfo
115    // to determine whether ILOG CPLEX has also concluded that the model
116    // has a feasible solution.
117     
118  } 
119
120  MipCplex::Value MipCplex::_getPrimal(int i){
121    Value x;
122    CPXgetmipx(env, lp, &x, i, i);
123    return x;
124  }
125 
126  MipCplex::Value MipCplex::_getPrimalValue(){
127    Value objval;
128    status = CPXgetmipobjval(env, lp, &objval);
129    return objval;
130  }
131} //END OF NAMESPACE LEMON
132
133#endif //END OF MIP_CPLEX_CC
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