COIN-OR::LEMON - Graph Library

source: lemon/lemon/mip_glpk.cc @ 481:7afc121e0689

Last change on this file since 481:7afc121e0689 was 481:7afc121e0689, checked in by Balazs Dezso <deba@…>, 11 years ago

Port LP and MIP solvers from SVN -r3509 (#44)

File size: 4.0 KB
Line 
1/* -*- mode: C++; indent-tabs-mode: nil; -*-
2 *
3 * This file is a part of LEMON, a generic C++ optimization library.
4 *
5 * Copyright (C) 2003-2008
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///\file
20///\brief Implementation of the LEMON-GLPK mip solver interface.
21
22#include <lemon/mip_glpk.h>
23
24extern "C" {
25#include <glpk.h>
26}
27
28#if GLP_MAJOR_VERSION > 4 || (GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION > 15)
29#define LEMON_glp(func) (glp_##func)
30#define LEMON_lpx(func) (lpx_##func)
31
32#define LEMON_GLP(def) (GLP_##def)
33#define LEMON_LPX(def) (LPX_##def)
34
35#else
36
37#define LEMON_glp(func) (lpx_##func)
38#define LEMON_lpx(func) (lpx_##func)
39
40#define LEMON_GLP(def) (LPX_##def)
41#define LEMON_LPX(def) (LPX_##def)
42
43#endif
44
45namespace lemon {
46
47  MipGlpk::MipGlpk() {
48#if !(GLP_MAJOR_VERSION > 4 || \
49      (GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION > 15))
50    LEMON_lpx(set_class)(lp,LEMON_GLP(MIP));
51#endif
52  }
53
54  void MipGlpk::_colType(int i, MipGlpk::ColTypes col_type){
55    switch (col_type){
56      case INT:
57        LEMON_glp(set_col_kind)(lp,i,LEMON_GLP(IV));
58        break;
59      case REAL:
60        LEMON_glp(set_col_kind)(lp,i,LEMON_GLP(CV));
61        break;
62    default:;
63        //FIXME problem
64    }
65  }
66
67  MipGlpk::ColTypes MipGlpk::_colType(int i) const {
68    switch (LEMON_glp(get_col_kind)(lp,i)){
69    case LEMON_GLP(IV):
70      return INT;//Or binary
71    case LEMON_GLP(CV):
72      return REAL;
73    default:
74      return REAL;//Error!
75    }
76
77  }
78
79  LpGlpk::SolveExitStatus MipGlpk::_solve() {
80    int result = LEMON_lpx(simplex)(lp);
81
82    // hack: mip does not contain integer variable
83#if GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION == 16
84    int tmp = -1;
85    if (LEMON_glp(get_num_int(lp)) == 0) {
86      tmp = LEMON_lpx(add_cols)(lp, 1);
87      LEMON_glp(set_col_bnds)(lp, tmp, LEMON_GLP(FX), 0.0, 0.0);
88      LEMON_glp(set_col_kind)(lp, tmp, LEMON_GLP(IV));
89    }
90#endif
91
92    if (LEMON_lpx(get_status)(lp)==LEMON_LPX(OPT)) {
93      //Maybe we could try the routine lpx_intopt(lp), a revised
94      //version of lpx_integer
95
96      result = LEMON_lpx(integer)(lp);
97      switch (result){
98      case LEMON_LPX(E_OK):
99        solved = true;
100        break;
101      default:
102        solved = false;
103      }
104    } else {
105      solved = false;
106    }
107#if GLP_MAJOR_VERSION == 4 && GLP_MINOR_VERSION == 16
108    if (tmp != -1) {
109      int tmpa[2];
110      tmpa[1] = tmp;
111      LEMON_lpx(del_cols)(lp, 1, tmpa);
112    }
113#endif
114    return solved ? SOLVED : UNSOLVED;
115  }
116
117
118  LpGlpk::SolutionStatus MipGlpk::_getMipStatus() const {
119
120    if (LEMON_lpx(get_status)(lp)==LEMON_LPX(OPT)){
121      //Meg kell nezni: ha az LP is infinite, akkor ez is, ha az is
122      //infeasible, akkor ez is, de ez lehet maskepp is infeasible.
123      int stat= LEMON_lpx(mip_status)(lp);
124
125      switch (stat) {
126      case LEMON_LPX(I_UNDEF)://Undefined (no solve has been run yet)
127        return UNDEFINED;
128      case LEMON_LPX(I_NOFEAS)://There is no feasible integral solution
129        return INFEASIBLE;
130        //     case LEMON_LPX(UNBND)://Unbounded
131        //       return INFINITE;
132      case LEMON_LPX(I_FEAS)://Feasible
133        return FEASIBLE;
134      case LEMON_LPX(I_OPT)://Feasible
135        return OPTIMAL;
136      default:
137        return UNDEFINED; //to avoid gcc warning
138      //FIXME error
139      }
140    }
141    else
142      return UNDEFINED; //Maybe we could refine this: what does the LP
143                        //relaxation look like
144
145  }
146
147  MipGlpk::Value MipGlpk::_getPrimal(int i) const {
148    return LEMON_glp(mip_col_val)(lp,i);
149  }
150
151  MipGlpk::Value MipGlpk::_getPrimalValue() const {
152    return LEMON_glp(mip_obj_val)(lp);
153  }
154} //END OF NAMESPACE LEMON
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