You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
169 lines
5.6 KiB
169 lines
5.6 KiB
/* glpapi05.c (LP basis constructing routines) */
|
|
|
|
/***********************************************************************
|
|
* This code is part of GLPK (GNU Linear Programming Kit).
|
|
*
|
|
* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
|
|
* 2009, 2010, 2011, 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_row_stat - set (change) row status
|
|
*
|
|
* SYNOPSIS
|
|
*
|
|
* void glp_set_row_stat(glp_prob *lp, int i, int stat);
|
|
*
|
|
* DESCRIPTION
|
|
*
|
|
* The routine glp_set_row_stat sets (changes) status of the auxiliary
|
|
* variable associated with i-th row.
|
|
*
|
|
* The new status of the auxiliary variable should be specified by the
|
|
* parameter stat as follows:
|
|
*
|
|
* GLP_BS - basic variable;
|
|
* GLP_NL - non-basic variable;
|
|
* GLP_NU - non-basic variable on its upper bound; if the variable is
|
|
* not double-bounded, this means the same as GLP_NL (only in
|
|
* case of this routine);
|
|
* GLP_NF - the same as GLP_NL (only in case of this routine);
|
|
* GLP_NS - the same as GLP_NL (only in case of this routine). */
|
|
|
|
void glp_set_row_stat(glp_prob *lp, int i, int stat)
|
|
{ GLPROW *row;
|
|
if (!(1 <= i && i <= lp->m))
|
|
xerror("glp_set_row_stat: i = %d; row number out of range\n",
|
|
i);
|
|
if (!(stat == GLP_BS || stat == GLP_NL || stat == GLP_NU ||
|
|
stat == GLP_NF || stat == GLP_NS))
|
|
xerror("glp_set_row_stat: i = %d; stat = %d; invalid status\n",
|
|
i, stat);
|
|
row = lp->row[i];
|
|
if (stat != GLP_BS)
|
|
{ switch (row->type)
|
|
{ case GLP_FR: stat = GLP_NF; break;
|
|
case GLP_LO: stat = GLP_NL; break;
|
|
case GLP_UP: stat = GLP_NU; break;
|
|
case GLP_DB: if (stat != GLP_NU) stat = GLP_NL; break;
|
|
case GLP_FX: stat = GLP_NS; break;
|
|
default: xassert(row != row);
|
|
}
|
|
}
|
|
if (row->stat == GLP_BS && stat != GLP_BS ||
|
|
row->stat != GLP_BS && stat == GLP_BS)
|
|
{ /* invalidate the basis factorization */
|
|
lp->valid = 0;
|
|
}
|
|
row->stat = stat;
|
|
return;
|
|
}
|
|
|
|
/***********************************************************************
|
|
* NAME
|
|
*
|
|
* glp_set_col_stat - set (change) column status
|
|
*
|
|
* SYNOPSIS
|
|
*
|
|
* void glp_set_col_stat(glp_prob *lp, int j, int stat);
|
|
*
|
|
* DESCRIPTION
|
|
*
|
|
* The routine glp_set_col_stat sets (changes) status of the structural
|
|
* variable associated with j-th column.
|
|
*
|
|
* The new status of the structural variable should be specified by the
|
|
* parameter stat as follows:
|
|
*
|
|
* GLP_BS - basic variable;
|
|
* GLP_NL - non-basic variable;
|
|
* GLP_NU - non-basic variable on its upper bound; if the variable is
|
|
* not double-bounded, this means the same as GLP_NL (only in
|
|
* case of this routine);
|
|
* GLP_NF - the same as GLP_NL (only in case of this routine);
|
|
* GLP_NS - the same as GLP_NL (only in case of this routine). */
|
|
|
|
void glp_set_col_stat(glp_prob *lp, int j, int stat)
|
|
{ GLPCOL *col;
|
|
if (!(1 <= j && j <= lp->n))
|
|
xerror("glp_set_col_stat: j = %d; column number out of range\n"
|
|
, j);
|
|
if (!(stat == GLP_BS || stat == GLP_NL || stat == GLP_NU ||
|
|
stat == GLP_NF || stat == GLP_NS))
|
|
xerror("glp_set_col_stat: j = %d; stat = %d; invalid status\n",
|
|
j, stat);
|
|
col = lp->col[j];
|
|
if (stat != GLP_BS)
|
|
{ switch (col->type)
|
|
{ case GLP_FR: stat = GLP_NF; break;
|
|
case GLP_LO: stat = GLP_NL; break;
|
|
case GLP_UP: stat = GLP_NU; break;
|
|
case GLP_DB: if (stat != GLP_NU) stat = GLP_NL; break;
|
|
case GLP_FX: stat = GLP_NS; break;
|
|
default: xassert(col != col);
|
|
}
|
|
}
|
|
if (col->stat == GLP_BS && stat != GLP_BS ||
|
|
col->stat != GLP_BS && stat == GLP_BS)
|
|
{ /* invalidate the basis factorization */
|
|
lp->valid = 0;
|
|
}
|
|
col->stat = stat;
|
|
return;
|
|
}
|
|
|
|
/***********************************************************************
|
|
* NAME
|
|
*
|
|
* glp_std_basis - construct standard initial LP basis
|
|
*
|
|
* SYNOPSIS
|
|
*
|
|
* void glp_std_basis(glp_prob *lp);
|
|
*
|
|
* DESCRIPTION
|
|
*
|
|
* The routine glp_std_basis builds the "standard" (trivial) initial
|
|
* basis for the specified problem object.
|
|
*
|
|
* In the "standard" basis all auxiliary variables are basic, and all
|
|
* structural variables are non-basic. */
|
|
|
|
void glp_std_basis(glp_prob *lp)
|
|
{ int i, j;
|
|
/* make all auxiliary variables basic */
|
|
for (i = 1; i <= lp->m; i++)
|
|
glp_set_row_stat(lp, i, GLP_BS);
|
|
/* make all structural variables non-basic */
|
|
for (j = 1; j <= lp->n; j++)
|
|
{ GLPCOL *col = lp->col[j];
|
|
if (col->type == GLP_DB && fabs(col->lb) > fabs(col->ub))
|
|
glp_set_col_stat(lp, j, GLP_NU);
|
|
else
|
|
glp_set_col_stat(lp, j, GLP_NL);
|
|
}
|
|
return;
|
|
}
|
|
|
|
/* eof */
|