/* glpapi04.c (problem scaling routines) */

/***********************************************************************

*  This code is part of GLPK (GNU Linear Programming Kit).

*

*  Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,

*  2009, 2010 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 "glpapi.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 */