lemon-project-template-glpk
view deps/glpk/src/glpapi05.c @ 9:33de93886c88
Import GLPK 4.47
| author | Alpar Juttner <alpar@cs.elte.hu> |
|---|---|
| date | Sun, 06 Nov 2011 20:59:10 +0100 |
| parents | |
| children |
line source
1 /* glpapi05.c (LP basis constructing routines) */
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, 2011 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 ***********************************************************************/
25 #include "glpapi.h"
27 /***********************************************************************
28 * NAME
29 *
30 * glp_set_row_stat - set (change) row status
31 *
32 * SYNOPSIS
33 *
34 * void glp_set_row_stat(glp_prob *lp, int i, int stat);
35 *
36 * DESCRIPTION
37 *
38 * The routine glp_set_row_stat sets (changes) status of the auxiliary
39 * variable associated with i-th row.
40 *
41 * The new status of the auxiliary variable should be specified by the
42 * parameter stat as follows:
43 *
44 * GLP_BS - basic variable;
45 * GLP_NL - non-basic variable;
46 * GLP_NU - non-basic variable on its upper bound; if the variable is
47 * not double-bounded, this means the same as GLP_NL (only in
48 * case of this routine);
49 * GLP_NF - the same as GLP_NL (only in case of this routine);
50 * GLP_NS - the same as GLP_NL (only in case of this routine). */
52 void glp_set_row_stat(glp_prob *lp, int i, int stat)
53 { GLPROW *row;
54 if (!(1 <= i && i <= lp->m))
55 xerror("glp_set_row_stat: i = %d; row number out of range\n",
56 i);
57 if (!(stat == GLP_BS || stat == GLP_NL || stat == GLP_NU ||
58 stat == GLP_NF || stat == GLP_NS))
59 xerror("glp_set_row_stat: i = %d; stat = %d; invalid status\n",
60 i, stat);
61 row = lp->row[i];
62 if (stat != GLP_BS)
63 { switch (row->type)
64 { case GLP_FR: stat = GLP_NF; break;
65 case GLP_LO: stat = GLP_NL; break;
66 case GLP_UP: stat = GLP_NU; break;
67 case GLP_DB: if (stat != GLP_NU) stat = GLP_NL; break;
68 case GLP_FX: stat = GLP_NS; break;
69 default: xassert(row != row);
70 }
71 }
72 if (row->stat == GLP_BS && stat != GLP_BS ||
73 row->stat != GLP_BS && stat == GLP_BS)
74 { /* invalidate the basis factorization */
75 lp->valid = 0;
76 }
77 row->stat = stat;
78 return;
79 }
81 /***********************************************************************
82 * NAME
83 *
84 * glp_set_col_stat - set (change) column status
85 *
86 * SYNOPSIS
87 *
88 * void glp_set_col_stat(glp_prob *lp, int j, int stat);
89 *
90 * DESCRIPTION
91 *
92 * The routine glp_set_col_stat sets (changes) status of the structural
93 * variable associated with j-th column.
94 *
95 * The new status of the structural variable should be specified by the
96 * parameter stat as follows:
97 *
98 * GLP_BS - basic variable;
99 * GLP_NL - non-basic variable;
100 * GLP_NU - non-basic variable on its upper bound; if the variable is
101 * not double-bounded, this means the same as GLP_NL (only in
102 * case of this routine);
103 * GLP_NF - the same as GLP_NL (only in case of this routine);
104 * GLP_NS - the same as GLP_NL (only in case of this routine). */
106 void glp_set_col_stat(glp_prob *lp, int j, int stat)
107 { GLPCOL *col;
108 if (!(1 <= j && j <= lp->n))
109 xerror("glp_set_col_stat: j = %d; column number out of range\n"
110 , j);
111 if (!(stat == GLP_BS || stat == GLP_NL || stat == GLP_NU ||
112 stat == GLP_NF || stat == GLP_NS))
113 xerror("glp_set_col_stat: j = %d; stat = %d; invalid status\n",
114 j, stat);
115 col = lp->col[j];
116 if (stat != GLP_BS)
117 { switch (col->type)
118 { case GLP_FR: stat = GLP_NF; break;
119 case GLP_LO: stat = GLP_NL; break;
120 case GLP_UP: stat = GLP_NU; break;
121 case GLP_DB: if (stat != GLP_NU) stat = GLP_NL; break;
122 case GLP_FX: stat = GLP_NS; break;
123 default: xassert(col != col);
124 }
125 }
126 if (col->stat == GLP_BS && stat != GLP_BS ||
127 col->stat != GLP_BS && stat == GLP_BS)
128 { /* invalidate the basis factorization */
129 lp->valid = 0;
130 }
131 col->stat = stat;
132 return;
133 }
135 /***********************************************************************
136 * NAME
137 *
138 * glp_std_basis - construct standard initial LP basis
139 *
140 * SYNOPSIS
141 *
142 * void glp_std_basis(glp_prob *lp);
143 *
144 * DESCRIPTION
145 *
146 * The routine glp_std_basis builds the "standard" (trivial) initial
147 * basis for the specified problem object.
148 *
149 * In the "standard" basis all auxiliary variables are basic, and all
150 * structural variables are non-basic. */
152 void glp_std_basis(glp_prob *lp)
153 { int i, j;
154 /* make all auxiliary variables basic */
155 for (i = 1; i <= lp->m; i++)
156 glp_set_row_stat(lp, i, GLP_BS);
157 /* make all structural variables non-basic */
158 for (j = 1; j <= lp->n; j++)
159 { GLPCOL *col = lp->col[j];
160 if (col->type == GLP_DB && fabs(col->lb) > fabs(col->ub))
161 glp_set_col_stat(lp, j, GLP_NU);
162 else
163 glp_set_col_stat(lp, j, GLP_NL);
164 }
165 return;
166 }
168 /* eof */