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 */ |
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