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1 /* glpapi04.c (problem scaling routines) */ |
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2 |
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3 /*********************************************************************** |
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4 * This code is part of GLPK (GNU Linear Programming Kit). |
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5 * |
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6 * Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, |
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7 * 2009, 2010 Andrew Makhorin, Department for Applied Informatics, |
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8 * Moscow Aviation Institute, Moscow, Russia. All rights reserved. |
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9 * E-mail: <mao@gnu.org>. |
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10 * |
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11 * GLPK is free software: you can redistribute it and/or modify it |
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12 * under the terms of the GNU General Public License as published by |
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13 * the Free Software Foundation, either version 3 of the License, or |
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14 * (at your option) any later version. |
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15 * |
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16 * GLPK is distributed in the hope that it will be useful, but WITHOUT |
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17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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18 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public |
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19 * License for more details. |
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20 * |
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21 * You should have received a copy of the GNU General Public License |
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22 * along with GLPK. If not, see <http://www.gnu.org/licenses/>. |
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23 ***********************************************************************/ |
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24 |
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25 #include "glpapi.h" |
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26 |
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27 /*********************************************************************** |
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28 * NAME |
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29 * |
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30 * glp_set_rii - set (change) row scale factor |
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31 * |
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32 * SYNOPSIS |
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33 * |
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34 * void glp_set_rii(glp_prob *lp, int i, double rii); |
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35 * |
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36 * DESCRIPTION |
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37 * |
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38 * The routine glp_set_rii sets (changes) the scale factor r[i,i] for |
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39 * i-th row of the specified problem object. */ |
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40 |
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41 void glp_set_rii(glp_prob *lp, int i, double rii) |
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42 { if (!(1 <= i && i <= lp->m)) |
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43 xerror("glp_set_rii: i = %d; row number out of range\n", i); |
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44 if (rii <= 0.0) |
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45 xerror("glp_set_rii: i = %d; rii = %g; invalid scale factor\n", |
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46 i, rii); |
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47 if (lp->valid && lp->row[i]->rii != rii) |
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48 { GLPAIJ *aij; |
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49 for (aij = lp->row[i]->ptr; aij != NULL; aij = aij->r_next) |
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50 { if (aij->col->stat == GLP_BS) |
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51 { /* invalidate the basis factorization */ |
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52 lp->valid = 0; |
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53 break; |
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54 } |
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55 } |
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56 } |
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57 lp->row[i]->rii = rii; |
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58 return; |
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59 } |
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60 |
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61 /*********************************************************************** |
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62 * NAME |
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63 * |
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64 * glp_set sjj - set (change) column scale factor |
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65 * |
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66 * SYNOPSIS |
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67 * |
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68 * void glp_set_sjj(glp_prob *lp, int j, double sjj); |
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69 * |
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70 * DESCRIPTION |
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71 * |
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72 * The routine glp_set_sjj sets (changes) the scale factor s[j,j] for |
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73 * j-th column of the specified problem object. */ |
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74 |
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75 void glp_set_sjj(glp_prob *lp, int j, double sjj) |
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76 { if (!(1 <= j && j <= lp->n)) |
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77 xerror("glp_set_sjj: j = %d; column number out of range\n", j); |
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78 if (sjj <= 0.0) |
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79 xerror("glp_set_sjj: j = %d; sjj = %g; invalid scale factor\n", |
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80 j, sjj); |
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81 if (lp->valid && lp->col[j]->sjj != sjj && lp->col[j]->stat == |
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82 GLP_BS) |
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83 { /* invalidate the basis factorization */ |
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84 lp->valid = 0; |
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85 } |
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86 lp->col[j]->sjj = sjj; |
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87 return; |
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88 } |
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89 |
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90 /*********************************************************************** |
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91 * NAME |
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92 * |
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93 * glp_get_rii - retrieve row scale factor |
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94 * |
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95 * SYNOPSIS |
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96 * |
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97 * double glp_get_rii(glp_prob *lp, int i); |
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98 * |
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99 * RETURNS |
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100 * |
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101 * The routine glp_get_rii returns current scale factor r[i,i] for i-th |
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102 * row of the specified problem object. */ |
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103 |
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104 double glp_get_rii(glp_prob *lp, int i) |
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105 { if (!(1 <= i && i <= lp->m)) |
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106 xerror("glp_get_rii: i = %d; row number out of range\n", i); |
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107 return lp->row[i]->rii; |
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108 } |
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109 |
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110 /*********************************************************************** |
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111 * NAME |
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112 * |
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113 * glp_get_sjj - retrieve column scale factor |
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114 * |
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115 * SYNOPSIS |
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116 * |
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117 * double glp_get_sjj(glp_prob *lp, int j); |
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118 * |
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119 * RETURNS |
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120 * |
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121 * The routine glp_get_sjj returns current scale factor s[j,j] for j-th |
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122 * column of the specified problem object. */ |
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123 |
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124 double glp_get_sjj(glp_prob *lp, int j) |
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125 { if (!(1 <= j && j <= lp->n)) |
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126 xerror("glp_get_sjj: j = %d; column number out of range\n", j); |
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127 return lp->col[j]->sjj; |
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128 } |
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129 |
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130 /*********************************************************************** |
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131 * NAME |
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132 * |
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133 * glp_unscale_prob - unscale problem data |
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134 * |
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135 * SYNOPSIS |
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136 * |
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137 * void glp_unscale_prob(glp_prob *lp); |
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138 * |
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139 * DESCRIPTION |
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140 * |
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141 * The routine glp_unscale_prob performs unscaling of problem data for |
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142 * the specified problem object. |
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143 * |
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144 * "Unscaling" means replacing the current scaling matrices R and S by |
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145 * unity matrices that cancels the scaling effect. */ |
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146 |
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147 void glp_unscale_prob(glp_prob *lp) |
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148 { int m = glp_get_num_rows(lp); |
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149 int n = glp_get_num_cols(lp); |
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150 int i, j; |
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151 for (i = 1; i <= m; i++) glp_set_rii(lp, i, 1.0); |
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152 for (j = 1; j <= n; j++) glp_set_sjj(lp, j, 1.0); |
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153 return; |
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154 } |
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155 |
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156 /* eof */ |