1 | // Copyright (C) 2002, International Business Machines |
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2 | // Corporation and others. All Rights Reserved. |
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3 | /* |
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4 | Authors |
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5 | |
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6 | Jeremy Omer, Mehdi Towhidi |
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7 | |
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8 | Last update: april 10, 2015 |
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9 | |
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10 | */ |
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11 | |
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12 | #ifndef ClpPEPrimalColumnSteepest_H |
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13 | #define ClpPEPrimalColumnSteepest_H |
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14 | |
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15 | #include "ClpPrimalColumnSteepest.hpp" |
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16 | #include "ClpFactorization.hpp" |
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17 | #include "ClpPESimplex.hpp" |
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18 | #include <bitset> |
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19 | |
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20 | //############################################################################# |
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21 | class CoinIndexedVector; |
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22 | |
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23 | /** Primal Column Pivot Steepest Edge Algorithm Class |
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24 | |
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25 | See Forrest-Goldfarb paper for algorithm |
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26 | |
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27 | */ |
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28 | |
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29 | class ClpPEPrimalColumnSteepest : public ClpPrimalColumnSteepest { |
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30 | public: |
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31 | ///@name Constructors and destructors |
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32 | //@{ |
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33 | /** Default Constructor |
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34 | 0 is exact devex, 1 full steepest, 2 is partial exact devex |
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35 | 3 switches between 0 and 2 depending on factorization |
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36 | 4 starts as partial dantzig/devex but then may switch between 0 and 2. |
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37 | By partial exact devex is meant that the weights are updated as normal |
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38 | but only part of the nonbasic variables are scanned. |
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39 | This can be faster on very easy problems. |
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40 | */ |
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41 | ClpPEPrimalColumnSteepest(double psi = 0.5, int mode = 3); |
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42 | |
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43 | /// Copy constructor |
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44 | ClpPEPrimalColumnSteepest(const ClpPEPrimalColumnSteepest &rhs); |
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45 | |
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46 | /// Assignment operator |
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47 | ClpPEPrimalColumnSteepest &operator=(const ClpPEPrimalColumnSteepest &rhs); |
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48 | |
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49 | /// Destructor |
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50 | virtual ~ClpPEPrimalColumnSteepest(); |
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51 | |
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52 | /// Clone |
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53 | virtual ClpPrimalColumnPivot *clone(bool copyData = true) const; |
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54 | |
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55 | public: |
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56 | ///@name Algorithmic methods |
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57 | //@{ |
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58 | |
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59 | /** Returns pivot column, -1 if none. |
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60 | The Packed CoinIndexedVector updates has cost updates - for normal LP |
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61 | that is just +-weight where a feasibility changed. It also has |
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62 | reduced cost from last iteration in pivot row |
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63 | Parts of operation split out into separate functions for |
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64 | profiling and speed |
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65 | */ |
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66 | virtual int pivotColumn(CoinIndexedVector *updates, |
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67 | CoinIndexedVector *spareRow1, |
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68 | CoinIndexedVector *spareRow2, |
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69 | CoinIndexedVector *spareColumn1, |
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70 | CoinIndexedVector *spareColumn2); |
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71 | |
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72 | //@} |
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73 | /** Save weights - this may initialize weights as well |
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74 | This is as parent but may initialize ClpPESimplex |
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75 | */ |
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76 | virtual void saveWeights(ClpSimplex *model, int mode); |
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77 | /// Updates weights - as ordinary but checks for zero moves |
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78 | virtual void updateWeights(CoinIndexedVector *input); |
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79 | //--------------------------------------------------------------------------- |
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80 | // Psi |
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81 | inline double psi() const |
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82 | { |
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83 | return psi_; |
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84 | } |
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85 | |
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86 | private: |
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87 | /* this PESimplex object is used to identify the compatible variables */ |
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88 | ClpPESimplex *modelPE_; |
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89 | |
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90 | /* psi is the factor used in the bi-dimensional pricing, it is < 1 and |
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91 | 1/psi grows with the priority given to compatible variables */ |
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92 | double psi_; |
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93 | |
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94 | /* useful counters for the update of the set of compatible variables */ |
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95 | int iCurrent_; |
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96 | int iInterval_; |
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97 | |
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98 | /* record if previous iterations concluded that compatibles should not be checked */ |
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99 | int coDegenCompatibles_; |
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100 | int coConsecutiveCompatibles_; |
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101 | bool updateCompatibles_; |
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102 | }; |
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103 | |
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104 | #endif |
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105 | |
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106 | /* vi: softtabstop=2 shiftwidth=2 expandtab tabstop=2 |
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107 | */ |
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