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/* prob4.c (problem scaling routines) */
/***********************************************************************
* This code is part of GLPK (GNU Linear Programming Kit).
*
* Copyright (C) 2000-2013 Andrew Makhorin, Department for Applied
* Informatics, Moscow Aviation Institute, Moscow, Russia. All rights
* reserved. E-mail: <mao@gnu.org>.
*
* GLPK is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* GLPK is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
* License for more details.
*
* You should have received a copy of the GNU General Public License
* along with GLPK. If not, see <http://www.gnu.org/licenses/>.
***********************************************************************/
#include "env.h"
#include "prob.h"
/***********************************************************************
* NAME
*
* glp_set_rii - set (change) row scale factor
*
* SYNOPSIS
*
* void glp_set_rii(glp_prob *lp, int i, double rii);
*
* DESCRIPTION
*
* The routine glp_set_rii sets (changes) the scale factor r[i,i] for
* i-th row of the specified problem object. */
void glp_set_rii(glp_prob *lp, int i, double rii)
{ if (!(1 <= i && i <= lp->m))
xerror("glp_set_rii: i = %d; row number out of range\n", i);
if (rii <= 0.0)
xerror("glp_set_rii: i = %d; rii = %g; invalid scale factor\n",
i, rii);
if (lp->valid && lp->row[i]->rii != rii)
{ GLPAIJ *aij;
for (aij = lp->row[i]->ptr; aij != NULL; aij = aij->r_next)
{ if (aij->col->stat == GLP_BS)
{ /* invalidate the basis factorization */
lp->valid = 0;
break;
}
}
}
lp->row[i]->rii = rii;
return;
}
/***********************************************************************
* NAME
*
* glp_set sjj - set (change) column scale factor
*
* SYNOPSIS
*
* void glp_set_sjj(glp_prob *lp, int j, double sjj);
*
* DESCRIPTION
*
* The routine glp_set_sjj sets (changes) the scale factor s[j,j] for
* j-th column of the specified problem object. */
void glp_set_sjj(glp_prob *lp, int j, double sjj)
{ if (!(1 <= j && j <= lp->n))
xerror("glp_set_sjj: j = %d; column number out of range\n", j);
if (sjj <= 0.0)
xerror("glp_set_sjj: j = %d; sjj = %g; invalid scale factor\n",
j, sjj);
if (lp->valid && lp->col[j]->sjj != sjj && lp->col[j]->stat ==
GLP_BS)
{ /* invalidate the basis factorization */
lp->valid = 0;
}
lp->col[j]->sjj = sjj;
return;
}
/***********************************************************************
* NAME
*
* glp_get_rii - retrieve row scale factor
*
* SYNOPSIS
*
* double glp_get_rii(glp_prob *lp, int i);
*
* RETURNS
*
* The routine glp_get_rii returns current scale factor r[i,i] for i-th
* row of the specified problem object. */
double glp_get_rii(glp_prob *lp, int i)
{ if (!(1 <= i && i <= lp->m))
xerror("glp_get_rii: i = %d; row number out of range\n", i);
return lp->row[i]->rii;
}
/***********************************************************************
* NAME
*
* glp_get_sjj - retrieve column scale factor
*
* SYNOPSIS
*
* double glp_get_sjj(glp_prob *lp, int j);
*
* RETURNS
*
* The routine glp_get_sjj returns current scale factor s[j,j] for j-th
* column of the specified problem object. */
double glp_get_sjj(glp_prob *lp, int j)
{ if (!(1 <= j && j <= lp->n))
xerror("glp_get_sjj: j = %d; column number out of range\n", j);
return lp->col[j]->sjj;
}
/***********************************************************************
* NAME
*
* glp_unscale_prob - unscale problem data
*
* SYNOPSIS
*
* void glp_unscale_prob(glp_prob *lp);
*
* DESCRIPTION
*
* The routine glp_unscale_prob performs unscaling of problem data for
* the specified problem object.
*
* "Unscaling" means replacing the current scaling matrices R and S by
* unity matrices that cancels the scaling effect. */
void glp_unscale_prob(glp_prob *lp)
{ int m = glp_get_num_rows(lp);
int n = glp_get_num_cols(lp);
int i, j;
for (i = 1; i <= m; i++) glp_set_rii(lp, i, 1.0);
for (j = 1; j <= n; j++) glp_set_sjj(lp, j, 1.0);
return;
}
/* eof */
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