1 | /* -*- C++ -*- |
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2 | * src/lemon/lp_base.h - Part of LEMON, a generic C++ optimization library |
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3 | * |
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4 | * Copyright (C) 2005 Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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5 | * (Egervary Combinatorial Optimization Research Group, EGRES). |
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6 | * |
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7 | * Permission to use, modify and distribute this software is granted |
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8 | * provided that this copyright notice appears in all copies. For |
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9 | * precise terms see the accompanying LICENSE file. |
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10 | * |
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11 | * This software is provided "AS IS" with no warranty of any kind, |
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12 | * express or implied, and with no claim as to its suitability for any |
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13 | * purpose. |
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14 | * |
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15 | */ |
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16 | |
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17 | #ifndef LEMON_LP_BASE_H |
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18 | #define LEMON_LP_BASE_H |
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19 | |
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20 | #include<vector> |
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21 | |
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22 | #include<lemon/error.h> |
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23 | |
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24 | #include"lin_expr.h" |
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25 | ///\file |
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26 | ///\brief The interface of the LP solver interface. |
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27 | namespace lemon { |
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28 | |
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29 | ///Internal data structure to convert floating id's to fix one's |
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30 | |
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31 | ///\todo This might by implemented to be usable in other places. |
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32 | class _FixId |
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33 | { |
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34 | std::vector<int> index; |
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35 | std::vector<int> cross; |
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36 | int first_free; |
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37 | public: |
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38 | _FixId() : first_free(-1) {}; |
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39 | ///Convert a floating id to a fix one |
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40 | |
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41 | ///\param n is a floating id |
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42 | ///\return the corresponding fix id |
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43 | int fixId(int n) {return cross[n];} |
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44 | ///Convert a fix id to a floating one |
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45 | |
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46 | ///\param n is a fix id |
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47 | ///\return the corresponding floating id |
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48 | int floatingId(int n) { return index[n];} |
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49 | ///Add a new floating id. |
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50 | |
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51 | ///\param n is a floating id |
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52 | ///\return the fix id of the new value |
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53 | ///\todo Multiple additions should also be handled. |
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54 | int insert(int n) |
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55 | { |
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56 | if(n>=int(cross.size())) { |
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57 | cross.resize(n+1); |
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58 | if(first_free==-1) { |
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59 | cross[n]=index.size(); |
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60 | index.push_back(n); |
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61 | } |
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62 | else { |
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63 | cross[n]=first_free; |
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64 | int next=index[first_free]; |
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65 | index[first_free]=n; |
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66 | first_free=next; |
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67 | } |
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68 | } |
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69 | else throw LogicError(); //floatingId-s must form a continuous range; |
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70 | } |
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71 | ///Remove a fix id. |
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72 | |
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73 | ///\param n is a fix id |
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74 | /// |
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75 | void erase(int n) |
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76 | { |
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77 | int fl=index[n]; |
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78 | index[n]=first_free; |
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79 | first_free=n; |
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80 | for(int i=fl+1;i<int(cross.size());++i) { |
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81 | cross[i-1]=cross[i]; |
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82 | index[cross[i]]--; |
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83 | } |
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84 | cross.pop_back(); |
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85 | } |
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86 | ///An upper bound on the largest fix id. |
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87 | |
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88 | ///\todo Do we need this? |
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89 | /// |
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90 | std::size_t maxFixId() { return cross.size()-1; } |
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91 | |
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92 | }; |
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93 | |
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94 | ///Common base class for LP solvers |
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95 | class LpSolverBase { |
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96 | |
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97 | public: |
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98 | |
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99 | /// \e |
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100 | typedef double Value; |
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101 | /// \e |
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102 | static const Value INF; |
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103 | |
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104 | ///\e |
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105 | class Col { protected: int id; friend class LpSolverBase; }; |
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106 | ///\e |
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107 | class Row { protected: int id; friend class LpSolverBase; }; |
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108 | |
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109 | typedef SparseLinExpr<Col, Value> Expr; |
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110 | |
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111 | protected: |
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112 | _FixId rows; |
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113 | _FixId cols; |
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114 | |
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115 | //MATRIX MANIPULATING FUNCTIONS |
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116 | |
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117 | /// \e |
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118 | virtual int _addCol() = 0; |
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119 | /// \e |
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120 | virtual int _addRow() = 0; |
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121 | /// \e |
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122 | |
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123 | /// \warning Arrays are indexed from 1 (datum at index 0 is ignored) |
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124 | /// |
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125 | virtual void _setRowCoeffs(int i, |
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126 | int length, |
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127 | int const * indices, |
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128 | Value const * values ) = 0; |
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129 | /// \e |
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130 | |
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131 | /// \warning Arrays are indexed from 1 (datum at index 0 is ignored) |
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132 | /// |
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133 | virtual void _setColCoeffs(int i, |
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134 | int length, |
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135 | int const * indices, |
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136 | Value const * values ) = 0; |
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137 | |
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138 | /// \e |
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139 | |
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140 | /// The lower bound of a variable (column) have to be given by an |
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141 | /// extended number of type Value, i.e. a finite number of type |
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142 | /// Value or -INF. |
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143 | virtual void _setColLowerBound(int i, Value value) = 0; |
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144 | /// \e |
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145 | |
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146 | /// The upper bound of a variable (column) have to be given by an |
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147 | /// extended number of type Value, i.e. a finite number of type |
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148 | /// Value or INF. |
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149 | virtual void _setColUpperBound(int i, Value value) = 0; |
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150 | /// \e |
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151 | |
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152 | /// The lower bound of a linear expression (row) have to be given by an |
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153 | /// extended number of type Value, i.e. a finite number of type |
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154 | /// Value or -INF. |
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155 | virtual void _setRowLowerBound(int i, Value value) = 0; |
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156 | /// \e |
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157 | |
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158 | /// The upper bound of a linear expression (row) have to be given by an |
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159 | /// extended number of type Value, i.e. a finite number of type |
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160 | /// Value or INF. |
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161 | virtual void _setRowUpperBound(int i, Value value) = 0; |
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162 | |
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163 | /// \e |
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164 | virtual void _setObjCoeff(int i, Value obj_coef) = 0; |
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165 | |
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166 | ///\e |
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167 | |
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168 | ///\bug unimplemented!!!! |
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169 | void clearObj() {} |
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170 | public: |
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171 | |
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172 | |
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173 | ///\e |
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174 | virtual ~LpSolverBase() {} |
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175 | |
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176 | ///Add a new empty column (i.e a new variable) to the LP |
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177 | Col addCol() { Col c; c.id=cols.insert(_addCol()); return c;} |
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178 | ///Add a new empty row (i.e a new constaint) to the LP |
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179 | Row addRow() { Row r; r.id=rows.insert(_addRow()); return r;} |
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180 | |
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181 | ///Add a new row (i.e a new constaint) to the LP |
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182 | |
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183 | ///\param l lower bound (-INF means no bound) |
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184 | ///\param e a linear expression (see \ref Expr) |
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185 | ///\param u upper bound (INF means no bound) |
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186 | ///\bug This is a temportary function. The interface will change to |
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187 | ///a better one. |
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188 | Row addRow(Value l,Expr e, Value u) { |
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189 | Row r=addRow(); |
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190 | std::vector<int> indices; |
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191 | std::vector<Value> values; |
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192 | indices.push_back(0); |
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193 | values.push_back(0); |
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194 | for(Expr::iterator i=e.begin(); i!=e.end(); ++i) { |
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195 | indices.push_back(cols.floatingId((*i).first.id)); |
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196 | values.push_back((*i).second); |
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197 | } |
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198 | _setRowCoeffs(rows.floatingId(r.id),indices.size()-1, |
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199 | &indices[0],&values[0]); |
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200 | _setRowLowerBound(rows.floatingId(r.id),l); |
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201 | _setRowUpperBound(rows.floatingId(r.id),l); |
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202 | return r; |
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203 | } |
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204 | |
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205 | /// Set the lower bound of a column (i.e a variable) |
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206 | |
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207 | /// The upper bound of a variable (column) have to be given by an |
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208 | /// extended number of type Value, i.e. a finite number of type |
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209 | /// Value or -INF. |
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210 | virtual void setColLowerBound(Col c, Value value) { |
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211 | _setColLowerBound(cols.floatingId(c.id),value); |
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212 | } |
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213 | /// Set the upper bound of a column (i.e a variable) |
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214 | |
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215 | /// The upper bound of a variable (column) have to be given by an |
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216 | /// extended number of type Value, i.e. a finite number of type |
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217 | /// Value or INF. |
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218 | virtual void setColUpperBound(Col c, Value value) { |
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219 | _setColUpperBound(cols.floatingId(c.id),value); |
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220 | }; |
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221 | /// Set the lower bound of a row (i.e a constraint) |
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222 | |
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223 | /// The lower bound of a linear expression (row) have to be given by an |
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224 | /// extended number of type Value, i.e. a finite number of type |
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225 | /// Value or -INF. |
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226 | virtual void setRowLowerBound(Row r, Value value) { |
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227 | _setRowLowerBound(rows.floatingId(r.id),value); |
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228 | }; |
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229 | /// Set the upper bound of a row (i.e a constraint) |
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230 | |
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231 | /// The upper bound of a linear expression (row) have to be given by an |
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232 | /// extended number of type Value, i.e. a finite number of type |
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233 | /// Value or INF. |
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234 | virtual void setRowUpperBound(Row r, Value value) { |
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235 | _setRowUpperBound(rows.floatingId(r.id),value); |
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236 | }; |
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237 | ///Set an element of the objective function |
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238 | void setObjCoeff(Col c, Value v) {_setObjCoeff(cols.floatingId(c.id),v); }; |
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239 | ///Set the objective function |
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240 | |
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241 | ///\param e is a linear expression of type \ref Expr. |
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242 | ///\todo What to do with the constant component? |
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243 | void setObj(Expr e) { |
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244 | clearObj(); |
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245 | for (Expr::iterator i=e.begin(); i!=e.end(); ++i) |
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246 | setObjCoeff((*i).first,(*i).second); |
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247 | } |
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248 | |
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249 | }; |
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250 | |
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251 | } //namespace lemon |
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252 | |
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253 | #endif //LEMON_LP_BASE_H |
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