1 | /* -*- C++ -*- |
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2 | * |
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3 | * This file is a part of LEMON, a generic C++ optimization library |
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4 | * |
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5 | * Copyright (C) 2003-2008 |
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6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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7 | * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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8 | * |
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9 | * Permission to use, modify and distribute this software is granted |
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10 | * provided that this copyright notice appears in all copies. For |
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11 | * precise terms see the accompanying LICENSE file. |
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12 | * |
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13 | * This software is provided "AS IS" with no warranty of any kind, |
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14 | * express or implied, and with no claim as to its suitability for any |
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15 | * purpose. |
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16 | * |
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17 | */ |
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18 | |
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19 | ///\file |
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20 | ///\brief Implementation of the LEMON-CPLEX mip solver interface. |
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21 | |
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22 | #include <lemon/mip_cplex.h> |
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23 | |
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24 | namespace lemon { |
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25 | |
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26 | MipCplex::MipCplex() { |
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27 | //This is unnecessary: setting integrality constraints on |
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28 | //variables will set this, too |
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29 | |
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30 | ///\todo The constant CPXPROB_MIP is |
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31 | ///called CPXPROB_MILP in later versions |
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32 | #if CPX_VERSION < 800 |
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33 | CPXchgprobtype( env, lp, CPXPROB_MIP); |
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34 | #else |
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35 | CPXchgprobtype( env, lp, CPXPROB_MILP); |
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36 | #endif |
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37 | |
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38 | } |
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39 | |
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40 | void MipCplex::_colType(int i, MipCplex::ColTypes col_type){ |
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41 | |
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42 | // Note If a variable is to be changed to binary, a call to CPXchgbds |
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43 | // should also be made to change the bounds to 0 and 1. |
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44 | |
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45 | int indices[1]; |
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46 | indices[0]=i; |
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47 | char ctype[1]; |
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48 | switch (col_type){ |
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49 | case INT: |
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50 | ctype[0]=CPX_INTEGER;//'I' |
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51 | break; |
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52 | case REAL: |
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53 | ctype[0]=CPX_CONTINUOUS ;//'C' |
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54 | break; |
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55 | default:; |
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56 | //FIXME problem |
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57 | } |
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58 | CPXchgctype (env, lp, 1, indices, ctype); |
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59 | } |
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60 | |
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61 | MipCplex::ColTypes MipCplex::_colType(int i) const { |
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62 | |
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63 | char ctype[1]; |
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64 | CPXgetctype (env, lp, ctype, i, i); |
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65 | switch (ctype[0]){ |
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66 | |
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67 | case CPX_INTEGER: |
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68 | return INT; |
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69 | case CPX_CONTINUOUS: |
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70 | return REAL; |
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71 | default: |
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72 | return REAL;//Error! |
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73 | } |
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74 | |
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75 | } |
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76 | |
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77 | LpCplex::SolveExitStatus MipCplex::_solve(){ |
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78 | |
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79 | status = CPXmipopt (env, lp); |
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80 | if (status==0) |
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81 | return SOLVED; |
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82 | else |
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83 | return UNSOLVED; |
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84 | |
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85 | } |
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86 | |
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87 | |
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88 | LpCplex::SolutionStatus MipCplex::_getMipStatus() const { |
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89 | |
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90 | int stat = CPXgetstat(env, lp); |
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91 | |
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92 | //Fortunately, MIP statuses did not change for cplex 8.0 |
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93 | switch (stat) |
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94 | { |
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95 | case CPXMIP_OPTIMAL: |
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96 | // Optimal integer solution has been found. |
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97 | case CPXMIP_OPTIMAL_TOL: |
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98 | // Optimal soluton with the tolerance defined by epgap or epagap has |
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99 | // been found. |
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100 | return OPTIMAL; |
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101 | //This also exists in later issues |
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102 | // case CPXMIP_UNBOUNDED: |
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103 | //return INFINITE; |
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104 | case CPXMIP_INFEASIBLE: |
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105 | return INFEASIBLE; |
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106 | default: |
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107 | return UNDEFINED; |
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108 | } |
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109 | //Unboundedness not treated well: the following is from cplex 9.0 doc |
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110 | // About Unboundedness |
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111 | |
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112 | // The treatment of models that are unbounded involves a few |
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113 | // subtleties. Specifically, a declaration of unboundedness means that |
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114 | // ILOG CPLEX has determined that the model has an unbounded |
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115 | // ray. Given any feasible solution x with objective z, a multiple of |
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116 | // the unbounded ray can be added to x to give a feasible solution |
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117 | // with objective z-1 (or z+1 for maximization models). Thus, if a |
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118 | // feasible solution exists, then the optimal objective is |
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119 | // unbounded. Note that ILOG CPLEX has not necessarily concluded that |
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120 | // a feasible solution exists. Users can call the routine CPXsolninfo |
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121 | // to determine whether ILOG CPLEX has also concluded that the model |
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122 | // has a feasible solution. |
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123 | |
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124 | } |
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125 | |
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126 | MipCplex::Value MipCplex::_getPrimal(int i) const { |
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127 | Value x; |
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128 | CPXgetmipx(env, lp, &x, i, i); |
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129 | return x; |
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130 | } |
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131 | |
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132 | MipCplex::Value MipCplex::_getPrimalValue() const { |
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133 | Value objval; |
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134 | CPXgetmipobjval(env, lp, &objval); |
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135 | return objval; |
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136 | } |
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137 | } //END OF NAMESPACE LEMON |
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