1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/deps/glpk/src/glpnpp05.c	Sun Nov 06 20:59:10 2011 +0100
     1.3 @@ -0,0 +1,809 @@
     1.4 +/* glpnpp05.c */
     1.5 +
     1.6 +/***********************************************************************
     1.7 +*  This code is part of GLPK (GNU Linear Programming Kit).
     1.8 +*
     1.9 +*  Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
    1.10 +*  2009, 2010, 2011 Andrew Makhorin, Department for Applied Informatics,
    1.11 +*  Moscow Aviation Institute, Moscow, Russia. All rights reserved.
    1.12 +*  E-mail: <mao@gnu.org>.
    1.13 +*
    1.14 +*  GLPK is free software: you can redistribute it and/or modify it
    1.15 +*  under the terms of the GNU General Public License as published by
    1.16 +*  the Free Software Foundation, either version 3 of the License, or
    1.17 +*  (at your option) any later version.
    1.18 +*
    1.19 +*  GLPK is distributed in the hope that it will be useful, but WITHOUT
    1.20 +*  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    1.21 +*  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
    1.22 +*  License for more details.
    1.23 +*
    1.24 +*  You should have received a copy of the GNU General Public License
    1.25 +*  along with GLPK. If not, see <http://www.gnu.org/licenses/>.
    1.26 +***********************************************************************/
    1.27 +
    1.28 +#include "glpnpp.h"
    1.29 +
    1.30 +/***********************************************************************
    1.31 +*  NAME
    1.32 +*
    1.33 +*  npp_clean_prob - perform initial LP/MIP processing
    1.34 +*
    1.35 +*  SYNOPSIS
    1.36 +*
    1.37 +*  #include "glpnpp.h"
    1.38 +*  void npp_clean_prob(NPP *npp);
    1.39 +*
    1.40 +*  DESCRIPTION
    1.41 +*
    1.42 +*  The routine npp_clean_prob performs initial LP/MIP processing that
    1.43 +*  currently includes:
    1.44 +*
    1.45 +*  1) removing free rows;
    1.46 +*
    1.47 +*  2) replacing double-sided constraint rows with almost identical
    1.48 +*     bounds, by equality constraint rows;
    1.49 +*
    1.50 +*  3) removing fixed columns;
    1.51 +*
    1.52 +*  4) replacing double-bounded columns with almost identical bounds by
    1.53 +*     fixed columns and removing those columns;
    1.54 +*
    1.55 +*  5) initial processing constraint coefficients (not implemented);
    1.56 +*
    1.57 +*  6) initial processing objective coefficients (not implemented). */
    1.58 +
    1.59 +void npp_clean_prob(NPP *npp)
    1.60 +{     /* perform initial LP/MIP processing */
    1.61 +      NPPROW *row, *next_row;
    1.62 +      NPPCOL *col, *next_col;
    1.63 +      int ret;
    1.64 +      xassert(npp == npp);
    1.65 +      /* process rows which originally are free */
    1.66 +      for (row = npp->r_head; row != NULL; row = next_row)
    1.67 +      {  next_row = row->next;
    1.68 +         if (row->lb == -DBL_MAX && row->ub == +DBL_MAX)
    1.69 +         {  /* process free row */
    1.70 +#ifdef GLP_DEBUG
    1.71 +            xprintf("1");
    1.72 +#endif
    1.73 +            npp_free_row(npp, row);
    1.74 +            /* row was deleted */
    1.75 +         }
    1.76 +      }
    1.77 +      /* process rows which originally are double-sided inequalities */
    1.78 +      for (row = npp->r_head; row != NULL; row = next_row)
    1.79 +      {  next_row = row->next;
    1.80 +         if (row->lb != -DBL_MAX && row->ub != +DBL_MAX &&
    1.81 +             row->lb < row->ub)
    1.82 +         {  ret = npp_make_equality(npp, row);
    1.83 +            if (ret == 0)
    1.84 +               ;
    1.85 +            else if (ret == 1)
    1.86 +            {  /* row was replaced by equality constraint */
    1.87 +#ifdef GLP_DEBUG
    1.88 +               xprintf("2");
    1.89 +#endif
    1.90 +            }
    1.91 +            else
    1.92 +               xassert(ret != ret);
    1.93 +         }
    1.94 +      }
    1.95 +      /* process columns which are originally fixed */
    1.96 +      for (col = npp->c_head; col != NULL; col = next_col)
    1.97 +      {  next_col = col->next;
    1.98 +         if (col->lb == col->ub)
    1.99 +         {  /* process fixed column */
   1.100 +#ifdef GLP_DEBUG
   1.101 +            xprintf("3");
   1.102 +#endif
   1.103 +            npp_fixed_col(npp, col);
   1.104 +            /* column was deleted */
   1.105 +         }
   1.106 +      }
   1.107 +      /* process columns which are originally double-bounded */
   1.108 +      for (col = npp->c_head; col != NULL; col = next_col)
   1.109 +      {  next_col = col->next;
   1.110 +         if (col->lb != -DBL_MAX && col->ub != +DBL_MAX &&
   1.111 +             col->lb < col->ub)
   1.112 +         {  ret = npp_make_fixed(npp, col);
   1.113 +            if (ret == 0)
   1.114 +               ;
   1.115 +            else if (ret == 1)
   1.116 +            {  /* column was replaced by fixed column; process it */
   1.117 +#ifdef GLP_DEBUG
   1.118 +               xprintf("4");
   1.119 +#endif
   1.120 +               npp_fixed_col(npp, col);
   1.121 +               /* column was deleted */
   1.122 +            }
   1.123 +         }
   1.124 +      }
   1.125 +      return;
   1.126 +}
   1.127 +
   1.128 +/***********************************************************************
   1.129 +*  NAME
   1.130 +*
   1.131 +*  npp_process_row - perform basic row processing
   1.132 +*
   1.133 +*  SYNOPSIS
   1.134 +*
   1.135 +*  #include "glpnpp.h"
   1.136 +*  int npp_process_row(NPP *npp, NPPROW *row, int hard);
   1.137 +*
   1.138 +*  DESCRIPTION
   1.139 +*
   1.140 +*  The routine npp_process_row performs basic row processing that
   1.141 +*  currently includes:
   1.142 +*
   1.143 +*  1) removing empty row;
   1.144 +*
   1.145 +*  2) removing equality constraint row singleton and corresponding
   1.146 +*     column;
   1.147 +*
   1.148 +*  3) removing inequality constraint row singleton and corresponding
   1.149 +*     column if it was fixed;
   1.150 +*
   1.151 +*  4) performing general row analysis;
   1.152 +*
   1.153 +*  5) removing redundant row bounds;
   1.154 +*
   1.155 +*  6) removing forcing row and corresponding columns;
   1.156 +*
   1.157 +*  7) removing row which becomes free due to redundant bounds;
   1.158 +*
   1.159 +*  8) computing implied bounds for all columns in the row and using
   1.160 +*     them to strengthen current column bounds (MIP only, optional,
   1.161 +*     performed if the flag hard is on).
   1.162 +*
   1.163 +*  Additionally the routine may activate affected rows and/or columns
   1.164 +*  for further processing.
   1.165 +*
   1.166 +*  RETURNS
   1.167 +*
   1.168 +*  0           success;
   1.169 +*
   1.170 +*  GLP_ENOPFS  primal/integer infeasibility detected;
   1.171 +*
   1.172 +*  GLP_ENODFS  dual infeasibility detected. */
   1.173 +
   1.174 +int npp_process_row(NPP *npp, NPPROW *row, int hard)
   1.175 +{     /* perform basic row processing */
   1.176 +      NPPCOL *col;
   1.177 +      NPPAIJ *aij, *next_aij, *aaa;
   1.178 +      int ret;
   1.179 +      /* row must not be free */
   1.180 +      xassert(!(row->lb == -DBL_MAX && row->ub == +DBL_MAX));
   1.181 +      /* start processing row */
   1.182 +      if (row->ptr == NULL)
   1.183 +      {  /* empty row */
   1.184 +         ret = npp_empty_row(npp, row);
   1.185 +         if (ret == 0)
   1.186 +         {  /* row was deleted */
   1.187 +#ifdef GLP_DEBUG
   1.188 +            xprintf("A");
   1.189 +#endif
   1.190 +            return 0;
   1.191 +         }
   1.192 +         else if (ret == 1)
   1.193 +         {  /* primal infeasibility */
   1.194 +            return GLP_ENOPFS;
   1.195 +         }
   1.196 +         else
   1.197 +            xassert(ret != ret);
   1.198 +      }
   1.199 +      if (row->ptr->r_next == NULL)
   1.200 +      {  /* row singleton */
   1.201 +         col = row->ptr->col;
   1.202 +         if (row->lb == row->ub)
   1.203 +         {  /* equality constraint */
   1.204 +            ret = npp_eq_singlet(npp, row);
   1.205 +            if (ret == 0)
   1.206 +            {  /* column was fixed, row was deleted */
   1.207 +#ifdef GLP_DEBUG
   1.208 +               xprintf("B");
   1.209 +#endif
   1.210 +               /* activate rows affected by column */
   1.211 +               for (aij = col->ptr; aij != NULL; aij = aij->c_next)
   1.212 +                  npp_activate_row(npp, aij->row);
   1.213 +               /* process fixed column */
   1.214 +               npp_fixed_col(npp, col);
   1.215 +               /* column was deleted */
   1.216 +               return 0;
   1.217 +            }
   1.218 +            else if (ret == 1 || ret == 2)
   1.219 +            {  /* primal/integer infeasibility */
   1.220 +               return GLP_ENOPFS;
   1.221 +            }
   1.222 +            else
   1.223 +               xassert(ret != ret);
   1.224 +         }
   1.225 +         else
   1.226 +         {  /* inequality constraint */
   1.227 +            ret = npp_ineq_singlet(npp, row);
   1.228 +            if (0 <= ret && ret <= 3)
   1.229 +            {  /* row was deleted */
   1.230 +#ifdef GLP_DEBUG
   1.231 +               xprintf("C");
   1.232 +#endif
   1.233 +               /* activate column, since its length was changed due to
   1.234 +                  row deletion */
   1.235 +               npp_activate_col(npp, col);
   1.236 +               if (ret >= 2)
   1.237 +               {  /* column bounds changed significantly or column was
   1.238 +                     fixed */
   1.239 +                  /* activate rows affected by column */
   1.240 +                  for (aij = col->ptr; aij != NULL; aij = aij->c_next)
   1.241 +                     npp_activate_row(npp, aij->row);
   1.242 +               }
   1.243 +               if (ret == 3)
   1.244 +               {  /* column was fixed; process it */
   1.245 +#ifdef GLP_DEBUG
   1.246 +                  xprintf("D");
   1.247 +#endif
   1.248 +                  npp_fixed_col(npp, col);
   1.249 +                  /* column was deleted */
   1.250 +               }
   1.251 +               return 0;
   1.252 +            }
   1.253 +            else if (ret == 4)
   1.254 +            {  /* primal infeasibility */
   1.255 +               return GLP_ENOPFS;
   1.256 +            }
   1.257 +            else
   1.258 +               xassert(ret != ret);
   1.259 +         }
   1.260 +      }
   1.261 +#if 0
   1.262 +      /* sometimes this causes too large round-off errors; probably
   1.263 +         pivot coefficient should be chosen more carefully */
   1.264 +      if (row->ptr->r_next->r_next == NULL)
   1.265 +      {  /* row doubleton */
   1.266 +         if (row->lb == row->ub)
   1.267 +         {  /* equality constraint */
   1.268 +            if (!(row->ptr->col->is_int ||
   1.269 +                  row->ptr->r_next->col->is_int))
   1.270 +            {  /* both columns are continuous */
   1.271 +               NPPCOL *q;
   1.272 +               q = npp_eq_doublet(npp, row);
   1.273 +               if (q != NULL)
   1.274 +               {  /* column q was eliminated */
   1.275 +#ifdef GLP_DEBUG
   1.276 +                  xprintf("E");
   1.277 +#endif
   1.278 +                  /* now column q is singleton of type "implied slack
   1.279 +                     variable"; we process it here to make sure that on
   1.280 +                     recovering basic solution the row is always active
   1.281 +                     equality constraint (as required by the routine
   1.282 +                     rcv_eq_doublet) */
   1.283 +                  xassert(npp_process_col(npp, q) == 0);
   1.284 +                  /* column q was deleted; note that row p also may be
   1.285 +                     deleted */
   1.286 +                  return 0;
   1.287 +               }
   1.288 +            }
   1.289 +         }
   1.290 +      }
   1.291 +#endif
   1.292 +      /* general row analysis */
   1.293 +      ret = npp_analyze_row(npp, row);
   1.294 +      xassert(0x00 <= ret && ret <= 0xFF);
   1.295 +      if (ret == 0x33)
   1.296 +      {  /* row bounds are inconsistent with column bounds */
   1.297 +         return GLP_ENOPFS;
   1.298 +      }
   1.299 +      if ((ret & 0x0F) == 0x00)
   1.300 +      {  /* row lower bound does not exist or redundant */
   1.301 +         if (row->lb != -DBL_MAX)
   1.302 +         {  /* remove redundant row lower bound */
   1.303 +#ifdef GLP_DEBUG
   1.304 +            xprintf("F");
   1.305 +#endif
   1.306 +            npp_inactive_bound(npp, row, 0);
   1.307 +         }
   1.308 +      }
   1.309 +      else if ((ret & 0x0F) == 0x01)
   1.310 +      {  /* row lower bound can be active */
   1.311 +         /* see below */
   1.312 +      }
   1.313 +      else if ((ret & 0x0F) == 0x02)
   1.314 +      {  /* row lower bound is a forcing bound */
   1.315 +#ifdef GLP_DEBUG
   1.316 +         xprintf("G");
   1.317 +#endif
   1.318 +         /* process forcing row */
   1.319 +         if (npp_forcing_row(npp, row, 0) == 0)
   1.320 +fixup:   {  /* columns were fixed, row was made free */
   1.321 +            for (aij = row->ptr; aij != NULL; aij = next_aij)
   1.322 +            {  /* process column fixed by forcing row */
   1.323 +#ifdef GLP_DEBUG
   1.324 +               xprintf("H");
   1.325 +#endif
   1.326 +               col = aij->col;
   1.327 +               next_aij = aij->r_next;
   1.328 +               /* activate rows affected by column */
   1.329 +               for (aaa = col->ptr; aaa != NULL; aaa = aaa->c_next)
   1.330 +                  npp_activate_row(npp, aaa->row);
   1.331 +               /* process fixed column */
   1.332 +               npp_fixed_col(npp, col);
   1.333 +               /* column was deleted */
   1.334 +            }
   1.335 +            /* process free row (which now is empty due to deletion of
   1.336 +               all its columns) */
   1.337 +            npp_free_row(npp, row);
   1.338 +            /* row was deleted */
   1.339 +            return 0;
   1.340 +         }
   1.341 +      }
   1.342 +      else
   1.343 +         xassert(ret != ret);
   1.344 +      if ((ret & 0xF0) == 0x00)
   1.345 +      {  /* row upper bound does not exist or redundant */
   1.346 +         if (row->ub != +DBL_MAX)
   1.347 +         {  /* remove redundant row upper bound */
   1.348 +#ifdef GLP_DEBUG
   1.349 +            xprintf("I");
   1.350 +#endif
   1.351 +            npp_inactive_bound(npp, row, 1);
   1.352 +         }
   1.353 +      }
   1.354 +      else if ((ret & 0xF0) == 0x10)
   1.355 +      {  /* row upper bound can be active */
   1.356 +         /* see below */
   1.357 +      }
   1.358 +      else if ((ret & 0xF0) == 0x20)
   1.359 +      {  /* row upper bound is a forcing bound */
   1.360 +#ifdef GLP_DEBUG
   1.361 +         xprintf("J");
   1.362 +#endif
   1.363 +         /* process forcing row */
   1.364 +         if (npp_forcing_row(npp, row, 1) == 0) goto fixup;
   1.365 +      }
   1.366 +      else
   1.367 +         xassert(ret != ret);
   1.368 +      if (row->lb == -DBL_MAX && row->ub == +DBL_MAX)
   1.369 +      {  /* row became free due to redundant bounds removal */
   1.370 +#ifdef GLP_DEBUG
   1.371 +         xprintf("K");
   1.372 +#endif
   1.373 +         /* activate its columns, since their length will change due
   1.374 +            to row deletion */
   1.375 +         for (aij = row->ptr; aij != NULL; aij = aij->r_next)
   1.376 +            npp_activate_col(npp, aij->col);
   1.377 +         /* process free row */
   1.378 +         npp_free_row(npp, row);
   1.379 +         /* row was deleted */
   1.380 +         return 0;
   1.381 +      }
   1.382 +#if 1 /* 23/XII-2009 */
   1.383 +      /* row lower and/or upper bounds can be active */
   1.384 +      if (npp->sol == GLP_MIP && hard)
   1.385 +      {  /* improve current column bounds (optional) */
   1.386 +         if (npp_improve_bounds(npp, row, 1) < 0)
   1.387 +            return GLP_ENOPFS;
   1.388 +      }
   1.389 +#endif
   1.390 +      return 0;
   1.391 +}
   1.392 +
   1.393 +/***********************************************************************
   1.394 +*  NAME
   1.395 +*
   1.396 +*  npp_improve_bounds - improve current column bounds
   1.397 +*
   1.398 +*  SYNOPSIS
   1.399 +*
   1.400 +*  #include "glpnpp.h"
   1.401 +*  int npp_improve_bounds(NPP *npp, NPPROW *row, int flag);
   1.402 +*
   1.403 +*  DESCRIPTION
   1.404 +*
   1.405 +*  The routine npp_improve_bounds analyzes specified row (inequality
   1.406 +*  or equality constraint) to determine implied column bounds and then
   1.407 +*  uses these bounds to improve (strengthen) current column bounds.
   1.408 +*
   1.409 +*  If the flag is on and current column bounds changed significantly
   1.410 +*  or the column was fixed, the routine activate rows affected by the
   1.411 +*  column for further processing. (This feature is intended to be used
   1.412 +*  in the main loop of the routine npp_process_row.)
   1.413 +*
   1.414 +*  NOTE: This operation can be used for MIP problem only.
   1.415 +*
   1.416 +*  RETURNS
   1.417 +*
   1.418 +*  The routine npp_improve_bounds returns the number of significantly
   1.419 +*  changed bounds plus the number of column having been fixed due to
   1.420 +*  bound improvements. However, if the routine detects primal/integer
   1.421 +*  infeasibility, it returns a negative value. */
   1.422 +
   1.423 +int npp_improve_bounds(NPP *npp, NPPROW *row, int flag)
   1.424 +{     /* improve current column bounds */
   1.425 +      NPPCOL *col;
   1.426 +      NPPAIJ *aij, *next_aij, *aaa;
   1.427 +      int kase, ret, count = 0;
   1.428 +      double lb, ub;
   1.429 +      xassert(npp->sol == GLP_MIP);
   1.430 +      /* row must not be free */
   1.431 +      xassert(!(row->lb == -DBL_MAX && row->ub == +DBL_MAX));
   1.432 +      /* determine implied column bounds */
   1.433 +      npp_implied_bounds(npp, row);
   1.434 +      /* and use these bounds to strengthen current column bounds */
   1.435 +      for (aij = row->ptr; aij != NULL; aij = next_aij)
   1.436 +      {  col = aij->col;
   1.437 +         next_aij = aij->r_next;
   1.438 +         for (kase = 0; kase <= 1; kase++)
   1.439 +         {  /* save current column bounds */
   1.440 +            lb = col->lb, ub = col->ub;
   1.441 +            if (kase == 0)
   1.442 +            {  /* process implied column lower bound */
   1.443 +               if (col->ll.ll == -DBL_MAX) continue;
   1.444 +               ret = npp_implied_lower(npp, col, col->ll.ll);
   1.445 +            }
   1.446 +            else
   1.447 +            {  /* process implied column upper bound */
   1.448 +               if (col->uu.uu == +DBL_MAX) continue;
   1.449 +               ret = npp_implied_upper(npp, col, col->uu.uu);
   1.450 +            }
   1.451 +            if (ret == 0 || ret == 1)
   1.452 +            {  /* current column bounds did not change or changed, but
   1.453 +                  not significantly; restore current column bounds */
   1.454 +               col->lb = lb, col->ub = ub;
   1.455 +            }
   1.456 +            else if (ret == 2 || ret == 3)
   1.457 +            {  /* current column bounds changed significantly or column
   1.458 +                  was fixed */
   1.459 +#ifdef GLP_DEBUG
   1.460 +               xprintf("L");
   1.461 +#endif
   1.462 +               count++;
   1.463 +               /* activate other rows affected by column, if required */
   1.464 +               if (flag)
   1.465 +               {  for (aaa = col->ptr; aaa != NULL; aaa = aaa->c_next)
   1.466 +                  {  if (aaa->row != row)
   1.467 +                        npp_activate_row(npp, aaa->row);
   1.468 +                  }
   1.469 +               }
   1.470 +               if (ret == 3)
   1.471 +               {  /* process fixed column */
   1.472 +#ifdef GLP_DEBUG
   1.473 +                  xprintf("M");
   1.474 +#endif
   1.475 +                  npp_fixed_col(npp, col);
   1.476 +                  /* column was deleted */
   1.477 +                  break; /* for kase */
   1.478 +               }
   1.479 +            }
   1.480 +            else if (ret == 4)
   1.481 +            {  /* primal/integer infeasibility */
   1.482 +               return -1;
   1.483 +            }
   1.484 +            else
   1.485 +               xassert(ret != ret);
   1.486 +         }
   1.487 +      }
   1.488 +      return count;
   1.489 +}
   1.490 +
   1.491 +/***********************************************************************
   1.492 +*  NAME
   1.493 +*
   1.494 +*  npp_process_col - perform basic column processing
   1.495 +*
   1.496 +*  SYNOPSIS
   1.497 +*
   1.498 +*  #include "glpnpp.h"
   1.499 +*  int npp_process_col(NPP *npp, NPPCOL *col);
   1.500 +*
   1.501 +*  DESCRIPTION
   1.502 +*
   1.503 +*  The routine npp_process_col performs basic column processing that
   1.504 +*  currently includes:
   1.505 +*
   1.506 +*  1) fixing and removing empty column;
   1.507 +*
   1.508 +*  2) removing column singleton, which is implied slack variable, and
   1.509 +*     corresponding row if it becomes free;
   1.510 +*
   1.511 +*  3) removing bounds of column, which is implied free variable, and
   1.512 +*     replacing corresponding row by equality constraint.
   1.513 +*
   1.514 +*  Additionally the routine may activate affected rows and/or columns
   1.515 +*  for further processing.
   1.516 +*
   1.517 +*  RETURNS
   1.518 +*
   1.519 +*  0           success;
   1.520 +*
   1.521 +*  GLP_ENOPFS  primal/integer infeasibility detected;
   1.522 +*
   1.523 +*  GLP_ENODFS  dual infeasibility detected. */
   1.524 +
   1.525 +int npp_process_col(NPP *npp, NPPCOL *col)
   1.526 +{     /* perform basic column processing */
   1.527 +      NPPROW *row;
   1.528 +      NPPAIJ *aij;
   1.529 +      int ret;
   1.530 +      /* column must not be fixed */
   1.531 +      xassert(col->lb < col->ub);
   1.532 +      /* start processing column */
   1.533 +      if (col->ptr == NULL)
   1.534 +      {  /* empty column */
   1.535 +         ret = npp_empty_col(npp, col);
   1.536 +         if (ret == 0)
   1.537 +         {  /* column was fixed and deleted */
   1.538 +#ifdef GLP_DEBUG
   1.539 +            xprintf("N");
   1.540 +#endif
   1.541 +            return 0;
   1.542 +         }
   1.543 +         else if (ret == 1)
   1.544 +         {  /* dual infeasibility */
   1.545 +            return GLP_ENODFS;
   1.546 +         }
   1.547 +         else
   1.548 +            xassert(ret != ret);
   1.549 +      }
   1.550 +      if (col->ptr->c_next == NULL)
   1.551 +      {  /* column singleton */
   1.552 +         row = col->ptr->row;
   1.553 +         if (row->lb == row->ub)
   1.554 +         {  /* equality constraint */
   1.555 +            if (!col->is_int)
   1.556 +slack:      {  /* implied slack variable */
   1.557 +#ifdef GLP_DEBUG
   1.558 +               xprintf("O");
   1.559 +#endif
   1.560 +               npp_implied_slack(npp, col);
   1.561 +               /* column was deleted */
   1.562 +               if (row->lb == -DBL_MAX && row->ub == +DBL_MAX)
   1.563 +               {  /* row became free due to implied slack variable */
   1.564 +#ifdef GLP_DEBUG
   1.565 +                  xprintf("P");
   1.566 +#endif
   1.567 +                  /* activate columns affected by row */
   1.568 +                  for (aij = row->ptr; aij != NULL; aij = aij->r_next)
   1.569 +                     npp_activate_col(npp, aij->col);
   1.570 +                  /* process free row */
   1.571 +                  npp_free_row(npp, row);
   1.572 +                  /* row was deleted */
   1.573 +               }
   1.574 +               else
   1.575 +               {  /* row became inequality constraint; activate it
   1.576 +                     since its length changed due to column deletion */
   1.577 +                  npp_activate_row(npp, row);
   1.578 +               }
   1.579 +               return 0;
   1.580 +            }
   1.581 +         }
   1.582 +         else
   1.583 +         {  /* inequality constraint */
   1.584 +            if (!col->is_int)
   1.585 +            {  ret = npp_implied_free(npp, col);
   1.586 +               if (ret == 0)
   1.587 +               {  /* implied free variable */
   1.588 +#ifdef GLP_DEBUG
   1.589 +                  xprintf("Q");
   1.590 +#endif
   1.591 +                  /* column bounds were removed, row was replaced by
   1.592 +                     equality constraint */
   1.593 +                  goto slack;
   1.594 +               }
   1.595 +               else if (ret == 1)
   1.596 +               {  /* column is not implied free variable, because its
   1.597 +                     lower and/or upper bounds can be active */
   1.598 +               }
   1.599 +               else if (ret == 2)
   1.600 +               {  /* dual infeasibility */
   1.601 +                  return GLP_ENODFS;
   1.602 +               }
   1.603 +            }
   1.604 +         }
   1.605 +      }
   1.606 +      /* column still exists */
   1.607 +      return 0;
   1.608 +}
   1.609 +
   1.610 +/***********************************************************************
   1.611 +*  NAME
   1.612 +*
   1.613 +*  npp_process_prob - perform basic LP/MIP processing
   1.614 +*
   1.615 +*  SYNOPSIS
   1.616 +*
   1.617 +*  #include "glpnpp.h"
   1.618 +*  int npp_process_prob(NPP *npp, int hard);
   1.619 +*
   1.620 +*  DESCRIPTION
   1.621 +*
   1.622 +*  The routine npp_process_prob performs basic LP/MIP processing that
   1.623 +*  currently includes:
   1.624 +*
   1.625 +*  1) initial LP/MIP processing (see the routine npp_clean_prob),
   1.626 +*
   1.627 +*  2) basic row processing (see the routine npp_process_row), and
   1.628 +*
   1.629 +*  3) basic column processing (see the routine npp_process_col).
   1.630 +*
   1.631 +*  If the flag hard is on, the routine attempts to improve current
   1.632 +*  column bounds multiple times within the main processing loop, in
   1.633 +*  which case this feature may take a time. Otherwise, if the flag hard
   1.634 +*  is off, improving column bounds is performed only once at the end of
   1.635 +*  the main loop. (Note that this feature is used for MIP only.)
   1.636 +*
   1.637 +*  The routine uses two sets: the set of active rows and the set of
   1.638 +*  active columns. Rows/columns are marked by a flag (the field temp in
   1.639 +*  NPPROW/NPPCOL). If the flag is non-zero, the row/column is active,
   1.640 +*  in which case it is placed in the beginning of the row/column list;
   1.641 +*  otherwise, if the flag is zero, the row/column is inactive, in which
   1.642 +*  case it is placed in the end of the row/column list. If a row/column
   1.643 +*  being currently processed may affect other rows/columns, the latters
   1.644 +*  are activated for further processing.
   1.645 +*
   1.646 +*  RETURNS
   1.647 +*
   1.648 +*  0           success;
   1.649 +*
   1.650 +*  GLP_ENOPFS  primal/integer infeasibility detected;
   1.651 +*
   1.652 +*  GLP_ENODFS  dual infeasibility detected. */
   1.653 +
   1.654 +int npp_process_prob(NPP *npp, int hard)
   1.655 +{     /* perform basic LP/MIP processing */
   1.656 +      NPPROW *row;
   1.657 +      NPPCOL *col;
   1.658 +      int processing, ret;
   1.659 +      /* perform initial LP/MIP processing */
   1.660 +      npp_clean_prob(npp);
   1.661 +      /* activate all remaining rows and columns */
   1.662 +      for (row = npp->r_head; row != NULL; row = row->next)
   1.663 +         row->temp = 1;
   1.664 +      for (col = npp->c_head; col != NULL; col = col->next)
   1.665 +         col->temp = 1;
   1.666 +      /* main processing loop */
   1.667 +      processing = 1;
   1.668 +      while (processing)
   1.669 +      {  processing = 0;
   1.670 +         /* process all active rows */
   1.671 +         for (;;)
   1.672 +         {  row = npp->r_head;
   1.673 +            if (row == NULL || !row->temp) break;
   1.674 +            npp_deactivate_row(npp, row);
   1.675 +            ret = npp_process_row(npp, row, hard);
   1.676 +            if (ret != 0) goto done;
   1.677 +            processing = 1;
   1.678 +         }
   1.679 +         /* process all active columns */
   1.680 +         for (;;)
   1.681 +         {  col = npp->c_head;
   1.682 +            if (col == NULL || !col->temp) break;
   1.683 +            npp_deactivate_col(npp, col);
   1.684 +            ret = npp_process_col(npp, col);
   1.685 +            if (ret != 0) goto done;
   1.686 +            processing = 1;
   1.687 +         }
   1.688 +      }
   1.689 +#if 1 /* 23/XII-2009 */
   1.690 +      if (npp->sol == GLP_MIP && !hard)
   1.691 +      {  /* improve current column bounds (optional) */
   1.692 +         for (row = npp->r_head; row != NULL; row = row->next)
   1.693 +         {  if (npp_improve_bounds(npp, row, 0) < 0)
   1.694 +            {  ret = GLP_ENOPFS;
   1.695 +               goto done;
   1.696 +            }
   1.697 +         }
   1.698 +      }
   1.699 +#endif
   1.700 +      /* all seems ok */
   1.701 +      ret = 0;
   1.702 +done: xassert(ret == 0 || ret == GLP_ENOPFS || ret == GLP_ENODFS);
   1.703 +#ifdef GLP_DEBUG
   1.704 +      xprintf("\n");
   1.705 +#endif
   1.706 +      return ret;
   1.707 +}
   1.708 +
   1.709 +/**********************************************************************/
   1.710 +
   1.711 +int npp_simplex(NPP *npp, const glp_smcp *parm)
   1.712 +{     /* process LP prior to applying primal/dual simplex method */
   1.713 +      int ret;
   1.714 +      xassert(npp->sol == GLP_SOL);
   1.715 +      xassert(parm == parm);
   1.716 +      ret = npp_process_prob(npp, 0);
   1.717 +      return ret;
   1.718 +}
   1.719 +
   1.720 +/**********************************************************************/
   1.721 +
   1.722 +int npp_integer(NPP *npp, const glp_iocp *parm)
   1.723 +{     /* process MIP prior to applying branch-and-bound method */
   1.724 +      NPPROW *row, *prev_row;
   1.725 +      NPPCOL *col;
   1.726 +      NPPAIJ *aij;
   1.727 +      int count, ret;
   1.728 +      xassert(npp->sol == GLP_MIP);
   1.729 +      xassert(parm == parm);
   1.730 +      /*==============================================================*/
   1.731 +      /* perform basic MIP processing */
   1.732 +      ret = npp_process_prob(npp, 1);
   1.733 +      if (ret != 0) goto done;
   1.734 +      /*==============================================================*/
   1.735 +      /* binarize problem, if required */
   1.736 +      if (parm->binarize)
   1.737 +         npp_binarize_prob(npp);
   1.738 +      /*==============================================================*/
   1.739 +      /* identify hidden packing inequalities */
   1.740 +      count = 0;
   1.741 +      /* new rows will be added to the end of the row list, so we go
   1.742 +         from the end to beginning of the row list */
   1.743 +      for (row = npp->r_tail; row != NULL; row = prev_row)
   1.744 +      {  prev_row = row->prev;
   1.745 +         /* skip free row */
   1.746 +         if (row->lb == -DBL_MAX && row->ub == +DBL_MAX) continue;
   1.747 +         /* skip equality constraint */
   1.748 +         if (row->lb == row->ub) continue;
   1.749 +         /* skip row having less than two variables */
   1.750 +         if (row->ptr == NULL || row->ptr->r_next == NULL) continue;
   1.751 +         /* skip row having non-binary variables */
   1.752 +         for (aij = row->ptr; aij != NULL; aij = aij->r_next)
   1.753 +         {  col = aij->col;
   1.754 +            if (!(col->is_int && col->lb == 0.0 && col->ub == 1.0))
   1.755 +               break;
   1.756 +         }
   1.757 +         if (aij != NULL) continue;
   1.758 +         count += npp_hidden_packing(npp, row);
   1.759 +      }
   1.760 +      if (count > 0)
   1.761 +         xprintf("%d hidden packing inequaliti(es) were detected\n",
   1.762 +            count);
   1.763 +      /*==============================================================*/
   1.764 +      /* identify hidden covering inequalities */
   1.765 +      count = 0;
   1.766 +      /* new rows will be added to the end of the row list, so we go
   1.767 +         from the end to beginning of the row list */
   1.768 +      for (row = npp->r_tail; row != NULL; row = prev_row)
   1.769 +      {  prev_row = row->prev;
   1.770 +         /* skip free row */
   1.771 +         if (row->lb == -DBL_MAX && row->ub == +DBL_MAX) continue;
   1.772 +         /* skip equality constraint */
   1.773 +         if (row->lb == row->ub) continue;
   1.774 +         /* skip row having less than three variables */
   1.775 +         if (row->ptr == NULL || row->ptr->r_next == NULL ||
   1.776 +             row->ptr->r_next->r_next == NULL) continue;
   1.777 +         /* skip row having non-binary variables */
   1.778 +         for (aij = row->ptr; aij != NULL; aij = aij->r_next)
   1.779 +         {  col = aij->col;
   1.780 +            if (!(col->is_int && col->lb == 0.0 && col->ub == 1.0))
   1.781 +               break;
   1.782 +         }
   1.783 +         if (aij != NULL) continue;
   1.784 +         count += npp_hidden_covering(npp, row);
   1.785 +      }
   1.786 +      if (count > 0)
   1.787 +         xprintf("%d hidden covering inequaliti(es) were detected\n",
   1.788 +            count);
   1.789 +      /*==============================================================*/
   1.790 +      /* reduce inequality constraint coefficients */
   1.791 +      count = 0;
   1.792 +      /* new rows will be added to the end of the row list, so we go
   1.793 +         from the end to beginning of the row list */
   1.794 +      for (row = npp->r_tail; row != NULL; row = prev_row)
   1.795 +      {  prev_row = row->prev;
   1.796 +         /* skip equality constraint */
   1.797 +         if (row->lb == row->ub) continue;
   1.798 +         count += npp_reduce_ineq_coef(npp, row);
   1.799 +      }
   1.800 +      if (count > 0)
   1.801 +         xprintf("%d constraint coefficient(s) were reduced\n", count);
   1.802 +      /*==============================================================*/
   1.803 +#ifdef GLP_DEBUG
   1.804 +      routine(npp);
   1.805 +#endif
   1.806 +      /*==============================================================*/
   1.807 +      /* all seems ok */
   1.808 +      ret = 0;
   1.809 +done: return ret;
   1.810 +}
   1.811 +
   1.812 +/* eof */