1 | /* $Id: CbcHeuristicDiveCoefficient.cpp 1173 2009-06-04 09:44:10Z forrest $ */ |
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2 | // Copyright (C) 2008, International Business Machines |
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3 | // Corporation and others. All Rights Reserved. |
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4 | // This code is licensed under the terms of the Eclipse Public License (EPL). |
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5 | |
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6 | #if defined(_MSC_VER) |
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7 | // Turn off compiler warning about long names |
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8 | # pragma warning(disable:4786) |
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9 | #endif |
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10 | |
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11 | //#define PRINT_DEBUG |
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12 | |
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13 | #include "CbcHeuristicDiveCoefficient.hpp" |
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14 | #include "CbcStrategy.hpp" |
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15 | |
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16 | // Default Constructor |
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17 | CbcHeuristicDiveCoefficient::CbcHeuristicDiveCoefficient() |
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18 | : CbcHeuristicDive() |
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19 | { |
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20 | } |
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21 | |
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22 | // Constructor from model |
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23 | CbcHeuristicDiveCoefficient::CbcHeuristicDiveCoefficient(CbcModel & model) |
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24 | : CbcHeuristicDive(model) |
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25 | { |
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26 | } |
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27 | |
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28 | // Destructor |
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29 | CbcHeuristicDiveCoefficient::~CbcHeuristicDiveCoefficient () |
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30 | { |
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31 | } |
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32 | |
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33 | // Clone |
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34 | CbcHeuristicDiveCoefficient * |
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35 | CbcHeuristicDiveCoefficient::clone() const |
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36 | { |
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37 | return new CbcHeuristicDiveCoefficient(*this); |
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38 | } |
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39 | |
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40 | // Create C++ lines to get to current state |
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41 | void |
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42 | CbcHeuristicDiveCoefficient::generateCpp( FILE * fp) |
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43 | { |
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44 | CbcHeuristicDiveCoefficient other; |
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45 | fprintf(fp, "0#include \"CbcHeuristicDiveCoefficient.hpp\"\n"); |
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46 | fprintf(fp, "3 CbcHeuristicDiveCoefficient heuristicDiveCoefficient(*cbcModel);\n"); |
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47 | CbcHeuristic::generateCpp(fp, "heuristicDiveCoefficient"); |
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48 | fprintf(fp, "3 cbcModel->addHeuristic(&heuristicDiveCoefficient);\n"); |
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49 | } |
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50 | |
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51 | // Copy constructor |
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52 | CbcHeuristicDiveCoefficient::CbcHeuristicDiveCoefficient(const CbcHeuristicDiveCoefficient & rhs) |
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53 | : |
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54 | CbcHeuristicDive(rhs) |
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55 | { |
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56 | } |
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57 | |
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58 | // Assignment operator |
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59 | CbcHeuristicDiveCoefficient & |
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60 | CbcHeuristicDiveCoefficient::operator=( const CbcHeuristicDiveCoefficient & rhs) |
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61 | { |
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62 | if (this != &rhs) { |
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63 | CbcHeuristicDive::operator=(rhs); |
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64 | } |
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65 | return *this; |
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66 | } |
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67 | |
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68 | bool |
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69 | CbcHeuristicDiveCoefficient::selectVariableToBranch(OsiSolverInterface* solver, |
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70 | const double* newSolution, |
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71 | int& bestColumn, |
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72 | int& bestRound) |
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73 | { |
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74 | int numberIntegers = model_->numberIntegers(); |
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75 | const int * integerVariable = model_->integerVariable(); |
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76 | double integerTolerance = model_->getDblParam(CbcModel::CbcIntegerTolerance); |
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77 | |
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78 | bestColumn = -1; |
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79 | bestRound = -1; // -1 rounds down, +1 rounds up |
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80 | double bestFraction = DBL_MAX; |
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81 | int bestLocks = COIN_INT_MAX; |
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82 | bool allTriviallyRoundableSoFar = true; |
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83 | for (int i = 0; i < numberIntegers; i++) { |
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84 | int iColumn = integerVariable[i]; |
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85 | double value = newSolution[iColumn]; |
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86 | double fraction = value - floor(value); |
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87 | int round = 0; |
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88 | if (fabs(floor(value + 0.5) - value) > integerTolerance) { |
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89 | int nDownLocks = downLocks_[i]; |
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90 | int nUpLocks = upLocks_[i]; |
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91 | if (allTriviallyRoundableSoFar || (nDownLocks > 0 && nUpLocks > 0)) { |
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92 | |
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93 | if (allTriviallyRoundableSoFar && nDownLocks > 0 && nUpLocks > 0) { |
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94 | allTriviallyRoundableSoFar = false; |
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95 | bestFraction = DBL_MAX; |
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96 | bestLocks = COIN_INT_MAX; |
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97 | } |
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98 | |
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99 | // the variable cannot be rounded |
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100 | int nLocks = nDownLocks; |
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101 | if (nDownLocks < nUpLocks) |
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102 | round = -1; |
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103 | else if (nDownLocks > nUpLocks) { |
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104 | round = 1; |
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105 | fraction = 1.0 - fraction; |
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106 | nLocks = nUpLocks; |
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107 | } else if (fraction < 0.5) |
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108 | round = -1; |
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109 | else { |
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110 | round = 1; |
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111 | fraction = 1.0 - fraction; |
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112 | nLocks = nUpLocks; |
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113 | } |
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114 | |
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115 | // if variable is not binary, penalize it |
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116 | if (!solver->isBinary(iColumn)) |
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117 | fraction *= 1000.0; |
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118 | |
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119 | if (nLocks < bestLocks || (nLocks == bestLocks && |
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120 | fraction < bestFraction)) { |
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121 | bestColumn = iColumn; |
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122 | bestLocks = nLocks; |
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123 | bestFraction = fraction; |
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124 | bestRound = round; |
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125 | } |
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126 | } |
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127 | } |
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128 | } |
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129 | return allTriviallyRoundableSoFar; |
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130 | } |
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131 | |
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