1 | /* $Id: ClpDualRowPivot.hpp 1732 2011-05-31 08:09:41Z forrest $ */ |
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2 | // Copyright (C) 2002, 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 | #ifndef ClpDualRowPivot_H |
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7 | #define ClpDualRowPivot_H |
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8 | |
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9 | class ClpSimplex; |
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10 | class CoinIndexedVector; |
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11 | |
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12 | //############################################################################# |
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13 | |
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14 | /** Dual Row Pivot Abstract Base Class |
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15 | |
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16 | Abstract Base Class for describing an interface to an algorithm |
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17 | to choose row pivot in dual simplex algorithm. For some algorithms |
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18 | e.g. Dantzig choice then some functions may be null. |
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19 | |
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20 | */ |
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21 | |
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22 | class ClpDualRowPivot { |
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23 | |
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24 | public: |
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25 | |
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26 | ///@name Algorithmic methods |
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27 | //@{ |
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28 | |
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29 | /// Returns pivot row, -1 if none |
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30 | virtual int pivotRow() = 0; |
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31 | |
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32 | /** Updates weights and returns pivot alpha. |
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33 | Also does FT update */ |
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34 | virtual double updateWeights(CoinIndexedVector * input, |
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35 | CoinIndexedVector * spare, |
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36 | CoinIndexedVector * spare2, |
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37 | CoinIndexedVector * updatedColumn) = 0; |
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38 | |
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39 | /** Updates primal solution (and maybe list of candidates) |
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40 | Uses input vector which it deletes |
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41 | Computes change in objective function |
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42 | Would be faster if we kept basic regions, but on other hand it |
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43 | means everything is always in sync |
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44 | */ |
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45 | /* FIXME: this was pure virtul (=0). Why? */ |
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46 | virtual void updatePrimalSolution(CoinIndexedVector * input, |
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47 | double theta, |
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48 | double & changeInObjective) = 0; |
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49 | /** Saves any weights round factorization as pivot rows may change |
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50 | Will be empty unless steepest edge (will save model) |
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51 | May also recompute infeasibility stuff |
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52 | 1) before factorization |
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53 | 2) after good factorization (if weights empty may initialize) |
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54 | 3) after something happened but no factorization |
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55 | (e.g. check for infeasible) |
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56 | 4) as 2 but restore weights from previous snapshot |
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57 | 5) for strong branching - initialize , infeasibilities |
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58 | */ |
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59 | virtual void saveWeights(ClpSimplex * model, int mode); |
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60 | /// checks accuracy and may re-initialize (may be empty) |
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61 | virtual void checkAccuracy(); |
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62 | /// Gets rid of last update (may be empty) |
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63 | virtual void unrollWeights(); |
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64 | /// Gets rid of all arrays (may be empty) |
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65 | virtual void clearArrays(); |
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66 | /// Returns true if would not find any row |
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67 | virtual bool looksOptimal() const { |
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68 | return false; |
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69 | } |
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70 | /// Called when maximum pivots changes |
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71 | virtual void maximumPivotsChanged() {} |
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72 | //@} |
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73 | |
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74 | |
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75 | ///@name Constructors and destructors |
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76 | //@{ |
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77 | /// Default Constructor |
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78 | ClpDualRowPivot(); |
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79 | |
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80 | /// Copy constructor |
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81 | ClpDualRowPivot(const ClpDualRowPivot &); |
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82 | |
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83 | /// Assignment operator |
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84 | ClpDualRowPivot & operator=(const ClpDualRowPivot& rhs); |
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85 | |
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86 | /// Destructor |
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87 | virtual ~ClpDualRowPivot (); |
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88 | |
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89 | /// Clone |
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90 | virtual ClpDualRowPivot * clone(bool copyData = true) const = 0; |
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91 | |
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92 | //@} |
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93 | |
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94 | ///@name Other |
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95 | //@{ |
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96 | /// Returns model |
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97 | inline ClpSimplex * model() { |
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98 | return model_; |
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99 | } |
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100 | |
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101 | /// Sets model (normally to NULL) |
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102 | inline void setModel(ClpSimplex * newmodel) { |
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103 | model_ = newmodel; |
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104 | } |
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105 | |
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106 | /// Returns type (above 63 is extra information) |
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107 | inline int type() { |
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108 | return type_; |
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109 | } |
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110 | |
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111 | //@} |
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112 | |
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113 | //--------------------------------------------------------------------------- |
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114 | |
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115 | protected: |
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116 | ///@name Protected member data |
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117 | //@{ |
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118 | /// Pointer to model |
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119 | ClpSimplex * model_; |
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120 | /// Type of row pivot algorithm |
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121 | int type_; |
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122 | //@} |
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123 | }; |
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124 | #ifndef CLP_DUAL_COLUMN_MULTIPLIER |
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125 | //#define CLP_DUAL_COLUMN_MULTIPLIER 0.99999 |
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126 | #endif |
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127 | #endif |
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