COIN-OR::LEMON - Graph Library

source: glpk-cmake/src/glpapi04.c @ 1:c445c931472f

Last change on this file since 1:c445c931472f was 1:c445c931472f, checked in by Alpar Juttner <alpar@…>, 10 years ago

Import glpk-4.45

  • Generated files and doc/notes are removed
File size: 4.5 KB
Line 
1/* glpapi04.c (problem scaling routines) */
2
3/***********************************************************************
4*  This code is part of GLPK (GNU Linear Programming Kit).
5*
6*  Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
7*  2009, 2010 Andrew Makhorin, Department for Applied Informatics,
8*  Moscow Aviation Institute, Moscow, Russia. All rights reserved.
9*  E-mail: <mao@gnu.org>.
10*
11*  GLPK is free software: you can redistribute it and/or modify it
12*  under the terms of the GNU General Public License as published by
13*  the Free Software Foundation, either version 3 of the License, or
14*  (at your option) any later version.
15*
16*  GLPK is distributed in the hope that it will be useful, but WITHOUT
17*  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
18*  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
19*  License for more details.
20*
21*  You should have received a copy of the GNU General Public License
22*  along with GLPK. If not, see <http://www.gnu.org/licenses/>.
23***********************************************************************/
24
25#include "glpapi.h"
26
27/***********************************************************************
28*  NAME
29*
30*  glp_set_rii - set (change) row scale factor
31*
32*  SYNOPSIS
33*
34*  void glp_set_rii(glp_prob *lp, int i, double rii);
35*
36*  DESCRIPTION
37*
38*  The routine glp_set_rii sets (changes) the scale factor r[i,i] for
39*  i-th row of the specified problem object. */
40
41void glp_set_rii(glp_prob *lp, int i, double rii)
42{     if (!(1 <= i && i <= lp->m))
43         xerror("glp_set_rii: i = %d; row number out of range\n", i);
44      if (rii <= 0.0)
45         xerror("glp_set_rii: i = %d; rii = %g; invalid scale factor\n",
46            i, rii);
47      if (lp->valid && lp->row[i]->rii != rii)
48      {  GLPAIJ *aij;
49         for (aij = lp->row[i]->ptr; aij != NULL; aij = aij->r_next)
50         {  if (aij->col->stat == GLP_BS)
51            {  /* invalidate the basis factorization */
52               lp->valid = 0;
53               break;
54            }
55         }
56      }
57      lp->row[i]->rii = rii;
58      return;
59}
60
61/***********************************************************************
62*  NAME
63*
64*  glp_set sjj - set (change) column scale factor
65*
66*  SYNOPSIS
67*
68*  void glp_set_sjj(glp_prob *lp, int j, double sjj);
69*
70*  DESCRIPTION
71*
72*  The routine glp_set_sjj sets (changes) the scale factor s[j,j] for
73*  j-th column of the specified problem object. */
74
75void glp_set_sjj(glp_prob *lp, int j, double sjj)
76{     if (!(1 <= j && j <= lp->n))
77         xerror("glp_set_sjj: j = %d; column number out of range\n", j);
78      if (sjj <= 0.0)
79         xerror("glp_set_sjj: j = %d; sjj = %g; invalid scale factor\n",
80            j, sjj);
81      if (lp->valid && lp->col[j]->sjj != sjj && lp->col[j]->stat ==
82         GLP_BS)
83      {  /* invalidate the basis factorization */
84         lp->valid = 0;
85      }
86      lp->col[j]->sjj = sjj;
87      return;
88}
89
90/***********************************************************************
91*  NAME
92*
93*  glp_get_rii - retrieve row scale factor
94*
95*  SYNOPSIS
96*
97*  double glp_get_rii(glp_prob *lp, int i);
98*
99*  RETURNS
100*
101*  The routine glp_get_rii returns current scale factor r[i,i] for i-th
102*  row of the specified problem object. */
103
104double glp_get_rii(glp_prob *lp, int i)
105{     if (!(1 <= i && i <= lp->m))
106         xerror("glp_get_rii: i = %d; row number out of range\n", i);
107      return lp->row[i]->rii;
108}
109
110/***********************************************************************
111*  NAME
112*
113*  glp_get_sjj - retrieve column scale factor
114*
115*  SYNOPSIS
116*
117*  double glp_get_sjj(glp_prob *lp, int j);
118*
119*  RETURNS
120*
121*  The routine glp_get_sjj returns current scale factor s[j,j] for j-th
122*  column of the specified problem object. */
123
124double glp_get_sjj(glp_prob *lp, int j)
125{     if (!(1 <= j && j <= lp->n))
126         xerror("glp_get_sjj: j = %d; column number out of range\n", j);
127      return lp->col[j]->sjj;
128}
129
130/***********************************************************************
131*  NAME
132*
133*  glp_unscale_prob - unscale problem data
134*
135*  SYNOPSIS
136*
137*  void glp_unscale_prob(glp_prob *lp);
138*
139*  DESCRIPTION
140*
141*  The routine glp_unscale_prob performs unscaling of problem data for
142*  the specified problem object.
143*
144*  "Unscaling" means replacing the current scaling matrices R and S by
145*  unity matrices that cancels the scaling effect. */
146
147void glp_unscale_prob(glp_prob *lp)
148{     int m = glp_get_num_rows(lp);
149      int n = glp_get_num_cols(lp);
150      int i, j;
151      for (i = 1; i <= m; i++) glp_set_rii(lp, i, 1.0);
152      for (j = 1; j <= n; j++) glp_set_sjj(lp, j, 1.0);
153      return;
154}
155
156/* eof */
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