/* glpapi09.c (mixed integer programming 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 "glpios.h"

 #include "glpnpp.h"

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

 *  NAME

 *

 *  glp_set_col_kind - set (change) column kind

 *

 *  SYNOPSIS

 *

 *  void glp_set_col_kind(glp_prob *mip, int j, int kind);

 *

 *  DESCRIPTION

 *

 *  The routine glp_set_col_kind sets (changes) the kind of j-th column

 *  (structural variable) as specified by the parameter kind:

 *

 *  GLP_CV - continuous variable;

 *  GLP_IV - integer variable;

 *  GLP_BV - binary variable. */

 void glp_set_col_kind(glp_prob *mip, int j, int kind)

 {     GLPCOL *col;

       if (!(1 <= j && j <= mip->n))

          xerror("glp_set_col_kind: j = %d; column number out of range\n"

             , j);

       col = mip->col[j];

       switch (kind)

       {  case GLP_CV:

             col->kind = GLP_CV;

             break;

          case GLP_IV:

             col->kind = GLP_IV;

             break;

          case GLP_BV:

             col->kind = GLP_IV;

             if (!(col->type == GLP_DB && col->lb == 0.0 && col->ub ==

                1.0)) glp_set_col_bnds(mip, j, GLP_DB, 0.0, 1.0);

             break;

          default:

             xerror("glp_set_col_kind: j = %d; kind = %d; invalid column"

                " kind\n", j, kind);

       }

       return;

 }

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

 *  NAME

 *

 *  glp_get_col_kind - retrieve column kind

 *

 *  SYNOPSIS

 *

 *  int glp_get_col_kind(glp_prob *mip, int j);

 *

 *  RETURNS

 *

 *  The routine glp_get_col_kind returns the kind of j-th column, i.e.

 *  the kind of corresponding structural variable, as follows:

 *

 *  GLP_CV - continuous variable;

 *  GLP_IV - integer variable;

 *  GLP_BV - binary variable */

 int glp_get_col_kind(glp_prob *mip, int j)

 {     GLPCOL *col;

       int kind;

       if (!(1 <= j && j <= mip->n))

          xerror("glp_get_col_kind: j = %d; column number out of range\n"

             , j);

       col = mip->col[j];

       kind = col->kind;

       switch (kind)

       {  case GLP_CV:

             break;

          case GLP_IV:

             if (col->type == GLP_DB && col->lb == 0.0 && col->ub == 1.0)

                kind = GLP_BV;

             break;

          default:

             xassert(kind != kind);

       }

       return kind;

 }

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

 *  NAME

 *

 *  glp_get_num_int - retrieve number of integer columns

 *

 *  SYNOPSIS

 *

 *  int glp_get_num_int(glp_prob *mip);

 *

 *  RETURNS

 *

 *  The routine glp_get_num_int returns the current number of columns,

 *  which are marked as integer. */

 int glp_get_num_int(glp_prob *mip)

 {     GLPCOL *col;

       int j, count = 0;

       for (j = 1; j <= mip->n; j++)

       {  col = mip->col[j];

          if (col->kind == GLP_IV) count++;

       }

       return count;

 }

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

 *  NAME

 *

 *  glp_get_num_bin - retrieve number of binary columns

 *

 *  SYNOPSIS

 *

 *  int glp_get_num_bin(glp_prob *mip);

 *

 *  RETURNS

 *

 *  The routine glp_get_num_bin returns the current number of columns,

 *  which are marked as binary. */

 int glp_get_num_bin(glp_prob *mip)

 {     GLPCOL *col;

       int j, count = 0;

       for (j = 1; j <= mip->n; j++)

       {  col = mip->col[j];

          if (col->kind == GLP_IV && col->type == GLP_DB && col->lb ==

             0.0 && col->ub == 1.0) count++;

       }

       return count;

 }

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

 *  NAME

 *

 *  glp_intopt - solve MIP problem with the branch-and-bound method

 *

 *  SYNOPSIS

 *

 *  int glp_intopt(glp_prob *P, const glp_iocp *parm);

 *

 *  DESCRIPTION

 *

 *  The routine glp_intopt is a driver to the MIP solver based on the

 *  branch-and-bound method.

 *

 *  On entry the problem object should contain optimal solution to LP

 *  relaxation (which can be obtained with the routine glp_simplex).

 *

 *  The MIP solver has a set of control parameters. Values of the control

 *  parameters can be passed in a structure glp_iocp, which the parameter

 *  parm points to.

 *

 *  The parameter parm can be specified as NULL, in which case the MIP

 *  solver uses default settings.

 *

 *  RETURNS

 *

 *  0  The MIP problem instance has been successfully solved. This code

 *     does not necessarily mean that the solver has found optimal

 *     solution. It only means that the solution process was successful.

 *

 *  GLP_EBOUND

 *     Unable to start the search, because some double-bounded variables

 *     have incorrect bounds or some integer variables have non-integer

 *     (fractional) bounds.

 *

 *  GLP_EROOT

 *     Unable to start the search, because optimal basis for initial LP

 *     relaxation is not provided.

 *

 *  GLP_EFAIL

 *     The search was prematurely terminated due to the solver failure.

 *

 *  GLP_EMIPGAP

 *     The search was prematurely terminated, because the relative mip

 *     gap tolerance has been reached.

 *

 *  GLP_ETMLIM

 *     The search was prematurely terminated, because the time limit has

 *     been exceeded.

 *

 *  GLP_ENOPFS

 *     The MIP problem instance has no primal feasible solution (only if

 *     the MIP presolver is used).

 *

 *  GLP_ENODFS

 *     LP relaxation of the MIP problem instance has no dual feasible

 *     solution (only if the MIP presolver is used).

 *

 *  GLP_ESTOP

 *     The search was prematurely terminated by application. */

 static int solve_mip(glp_prob *P, const glp_iocp *parm)

 {     /* solve MIP directly without using the preprocessor */

       glp_tree *T;

       int ret;

       /* optimal basis to LP relaxation must be provided */

       if (glp_get_status(P) != GLP_OPT)

       {  if (parm->msg_lev >= GLP_MSG_ERR)

             xprintf("glp_intopt: optimal basis to initial LP relaxation"

                " not provided\n");

          ret = GLP_EROOT;

          goto done;

       }

       /* it seems all is ok */

       if (parm->msg_lev >= GLP_MSG_ALL)

          xprintf("Integer optimization begins...\n");

       /* create the branch-and-bound tree */

       T = ios_create_tree(P, parm);

       /* solve the problem instance */

       ret = ios_driver(T);

       /* delete the branch-and-bound tree */

       ios_delete_tree(T);

       /* analyze exit code reported by the mip driver */

       if (ret == 0)

       {  if (P->mip_stat == GLP_FEAS)

          {  if (parm->msg_lev >= GLP_MSG_ALL)

                xprintf("INTEGER OPTIMAL SOLUTION FOUND\n");

             P->mip_stat = GLP_OPT;

          }

          else

          {  if (parm->msg_lev >= GLP_MSG_ALL)

                xprintf("PROBLEM HAS NO INTEGER FEASIBLE SOLUTION\n");

             P->mip_stat = GLP_NOFEAS;

          }

       }

       else if (ret == GLP_EMIPGAP)

       {  if (parm->msg_lev >= GLP_MSG_ALL)

             xprintf("RELATIVE MIP GAP TOLERANCE REACHED; SEARCH TERMINA"

                "TED\n");

       }

       else if (ret == GLP_ETMLIM)

       {  if (parm->msg_lev >= GLP_MSG_ALL)

             xprintf("TIME LIMIT EXCEEDED; SEARCH TERMINATED\n");

       }

       else if (ret == GLP_EFAIL)

       {  if (parm->msg_lev >= GLP_MSG_ERR)

             xprintf("glp_intopt: cannot solve current LP relaxation\n");

       }

       else if (ret == GLP_ESTOP)

       {  if (parm->msg_lev >= GLP_MSG_ALL)

             xprintf("SEARCH TERMINATED BY APPLICATION\n");

       }

       else

          xassert(ret != ret);

 done: return ret;

 }

 static int preprocess_and_solve_mip(glp_prob *P, const glp_iocp *parm)

 {     /* solve MIP using the preprocessor */

       ENV *env = get_env_ptr();

       int term_out = env->term_out;

       NPP *npp;

       glp_prob *mip = NULL;

       glp_bfcp bfcp;

       glp_smcp smcp;

       int ret;

       if (parm->msg_lev >= GLP_MSG_ALL)

          xprintf("Preprocessing...\n");

       /* create preprocessor workspace */

       npp = npp_create_wksp();

       /* load original problem into the preprocessor workspace */

       npp_load_prob(npp, P, GLP_OFF, GLP_MIP, GLP_OFF);

       /* process MIP prior to applying the branch-and-bound method */

       if (!term_out || parm->msg_lev < GLP_MSG_ALL)

          env->term_out = GLP_OFF;

       else

          env->term_out = GLP_ON;

       ret = npp_integer(npp, parm);

       env->term_out = term_out;

       if (ret == 0)

          ;

       else if (ret == GLP_ENOPFS)

       {  if (parm->msg_lev >= GLP_MSG_ALL)

             xprintf("PROBLEM HAS NO PRIMAL FEASIBLE SOLUTION\n");

       }

       else if (ret == GLP_ENODFS)

       {  if (parm->msg_lev >= GLP_MSG_ALL)

             xprintf("LP RELAXATION HAS NO DUAL FEASIBLE SOLUTION\n");

       }

       else

          xassert(ret != ret);

       if (ret != 0) goto done;

       /* build transformed MIP */

       mip = glp_create_prob();

       npp_build_prob(npp, mip);

       /* if the transformed MIP is empty, it has empty solution, which

          is optimal */

       if (mip->m == 0 && mip->n == 0)

       {  mip->mip_stat = GLP_OPT;

          mip->mip_obj = mip->c0;

          if (parm->msg_lev >= GLP_MSG_ALL)

          {  xprintf("Objective value = %17.9e\n", mip->mip_obj);

             xprintf("INTEGER OPTIMAL SOLUTION FOUND BY MIP PREPROCESSOR"

                "\n");

          }

          goto post;

       }

       /* display some statistics */

       if (parm->msg_lev >= GLP_MSG_ALL)

       {  int ni = glp_get_num_int(mip);

          int nb = glp_get_num_bin(mip);

          char s[50];

          xprintf("%d row%s, %d column%s, %d non-zero%s\n",

             mip->m, mip->m == 1 ? "" : "s", mip->n, mip->n == 1 ? "" :

             "s", mip->nnz, mip->nnz == 1 ? "" : "s");

          if (nb == 0)

             strcpy(s, "none of");

          else if (ni == 1 && nb == 1)

             strcpy(s, "");

          else if (nb == 1)

             strcpy(s, "one of");

          else if (nb == ni)

             strcpy(s, "all of");

          else

             sprintf(s, "%d of", nb);

          xprintf("%d integer variable%s, %s which %s binary\n",

             ni, ni == 1 ? "" : "s", s, nb == 1 ? "is" : "are");

       }

       /* inherit basis factorization control parameters */

       glp_get_bfcp(P, &bfcp);

       glp_set_bfcp(mip, &bfcp);

       /* scale the transformed problem */

       if (!term_out || parm->msg_lev < GLP_MSG_ALL)

          env->term_out = GLP_OFF;

       else

          env->term_out = GLP_ON;

       glp_scale_prob(mip,

          GLP_SF_GM | GLP_SF_EQ | GLP_SF_2N | GLP_SF_SKIP);

       env->term_out = term_out;

       /* build advanced initial basis */

       if (!term_out || parm->msg_lev < GLP_MSG_ALL)

          env->term_out = GLP_OFF;

       else

          env->term_out = GLP_ON;

       glp_adv_basis(mip, 0);

       env->term_out = term_out;

       /* solve initial LP relaxation */

       if (parm->msg_lev >= GLP_MSG_ALL)

          xprintf("Solving LP relaxation...\n");

       glp_init_smcp(&smcp);

       smcp.msg_lev = parm->msg_lev;

       mip->it_cnt = P->it_cnt;

       ret = glp_simplex(mip, &smcp);

       P->it_cnt = mip->it_cnt;

       if (ret != 0)

       {  if (parm->msg_lev >= GLP_MSG_ERR)

             xprintf("glp_intopt: cannot solve LP relaxation\n");

          ret = GLP_EFAIL;

          goto done;

       }

       /* check status of the basic solution */

       ret = glp_get_status(mip);

       if (ret == GLP_OPT)

          ret = 0;

       else if (ret == GLP_NOFEAS)

          ret = GLP_ENOPFS;

       else if (ret == GLP_UNBND)

          ret = GLP_ENODFS;

       else

          xassert(ret != ret);

       if (ret != 0) goto done;

       /* solve the transformed MIP */

       mip->it_cnt = P->it_cnt;

       ret = solve_mip(mip, parm);

       P->it_cnt = mip->it_cnt;

       /* only integer feasible solution can be postprocessed */

       if (!(mip->mip_stat == GLP_OPT || mip->mip_stat == GLP_FEAS))

       {  P->mip_stat = mip->mip_stat;

          goto done;

       }

       /* postprocess solution from the transformed MIP */

 post: npp_postprocess(npp, mip);

       /* the transformed MIP is no longer needed */

       glp_delete_prob(mip), mip = NULL;

       /* store solution to the original problem */

       npp_unload_sol(npp, P);

 done: /* delete the transformed MIP, if it exists */

       if (mip != NULL) glp_delete_prob(mip);

       /* delete preprocessor workspace */

       npp_delete_wksp(npp);

       return ret;

 }

 #ifndef HAVE_ALIEN_SOLVER /* 28/V-2010 */

 int _glp_intopt1(glp_prob *P, const glp_iocp *parm)

 {     xassert(P == P);

       xassert(parm == parm);

       xprintf("glp_intopt: no alien solver is available\n");

       return GLP_EFAIL;

 }

 #endif

 int glp_intopt(glp_prob *P, const glp_iocp *parm)

 {     /* solve MIP problem with the branch-and-bound method */

       glp_iocp _parm;

       int i, j, ret;

       /* check problem object */

       if (P == NULL || P->magic != GLP_PROB_MAGIC)

          xerror("glp_intopt: P = %p; invalid problem object\n", P);

       if (P->tree != NULL)

          xerror("glp_intopt: operation not allowed\n");

       /* check control parameters */

       if (parm == NULL)

          parm = &_parm, glp_init_iocp((glp_iocp *)parm);

       if (!(parm->msg_lev == GLP_MSG_OFF ||

             parm->msg_lev == GLP_MSG_ERR ||

             parm->msg_lev == GLP_MSG_ON  ||

             parm->msg_lev == GLP_MSG_ALL ||

             parm->msg_lev == GLP_MSG_DBG))

          xerror("glp_intopt: msg_lev = %d; invalid parameter\n",

             parm->msg_lev);

       if (!(parm->br_tech == GLP_BR_FFV ||

             parm->br_tech == GLP_BR_LFV ||

             parm->br_tech == GLP_BR_MFV ||

             parm->br_tech == GLP_BR_DTH ||

             parm->br_tech == GLP_BR_PCH))

          xerror("glp_intopt: br_tech = %d; invalid parameter\n",

             parm->br_tech);

       if (!(parm->bt_tech == GLP_BT_DFS ||

             parm->bt_tech == GLP_BT_BFS ||

             parm->bt_tech == GLP_BT_BLB ||

             parm->bt_tech == GLP_BT_BPH))

          xerror("glp_intopt: bt_tech = %d; invalid parameter\n",

             parm->bt_tech);

       if (!(0.0 < parm->tol_int && parm->tol_int < 1.0))

          xerror("glp_intopt: tol_int = %g; invalid parameter\n",

             parm->tol_int);

       if (!(0.0 < parm->tol_obj && parm->tol_obj < 1.0))

          xerror("glp_intopt: tol_obj = %g; invalid parameter\n",

             parm->tol_obj);

       if (parm->tm_lim < 0)

          xerror("glp_intopt: tm_lim = %d; invalid parameter\n",

             parm->tm_lim);

       if (parm->out_frq < 0)

          xerror("glp_intopt: out_frq = %d; invalid parameter\n",

             parm->out_frq);

       if (parm->out_dly < 0)

          xerror("glp_intopt: out_dly = %d; invalid parameter\n",

             parm->out_dly);

       if (!(0 <= parm->cb_size && parm->cb_size <= 256))

          xerror("glp_intopt: cb_size = %d; invalid parameter\n",

             parm->cb_size);

       if (!(parm->pp_tech == GLP_PP_NONE ||

             parm->pp_tech == GLP_PP_ROOT ||

             parm->pp_tech == GLP_PP_ALL))

          xerror("glp_intopt: pp_tech = %d; invalid parameter\n",

             parm->pp_tech);

       if (parm->mip_gap < 0.0)

          xerror("glp_intopt: mip_gap = %g; invalid parameter\n",

             parm->mip_gap);

       if (!(parm->mir_cuts == GLP_ON || parm->mir_cuts == GLP_OFF))

          xerror("glp_intopt: mir_cuts = %d; invalid parameter\n",

             parm->mir_cuts);

       if (!(parm->gmi_cuts == GLP_ON || parm->gmi_cuts == GLP_OFF))

          xerror("glp_intopt: gmi_cuts = %d; invalid parameter\n",

             parm->gmi_cuts);

       if (!(parm->cov_cuts == GLP_ON || parm->cov_cuts == GLP_OFF))

          xerror("glp_intopt: cov_cuts = %d; invalid parameter\n",

             parm->cov_cuts);

       if (!(parm->clq_cuts == GLP_ON || parm->clq_cuts == GLP_OFF))

          xerror("glp_intopt: clq_cuts = %d; invalid parameter\n",

             parm->clq_cuts);

       if (!(parm->presolve == GLP_ON || parm->presolve == GLP_OFF))

          xerror("glp_intopt: presolve = %d; invalid parameter\n",

             parm->presolve);

       if (!(parm->binarize == GLP_ON || parm->binarize == GLP_OFF))

          xerror("glp_intopt: binarize = %d; invalid parameter\n",

             parm->binarize);

       if (!(parm->fp_heur == GLP_ON || parm->fp_heur == GLP_OFF))

          xerror("glp_intopt: fp_heur = %d; invalid parameter\n",

             parm->fp_heur);

 #if 1 /* 28/V-2010 */

       if (!(parm->alien == GLP_ON || parm->alien == GLP_OFF))

          xerror("glp_intopt: alien = %d; invalid parameter\n",

             parm->alien);

 #endif

       /* integer solution is currently undefined */

       P->mip_stat = GLP_UNDEF;

       P->mip_obj = 0.0;

       /* check bounds of double-bounded variables */

       for (i = 1; i <= P->m; i++)

       {  GLPROW *row = P->row[i];

          if (row->type == GLP_DB && row->lb >= row->ub)

          {  if (parm->msg_lev >= GLP_MSG_ERR)

                xprintf("glp_intopt: row %d: lb = %g, ub = %g; incorrect"

                   " bounds\n", i, row->lb, row->ub);

             ret = GLP_EBOUND;

             goto done;

          }

       }

       for (j = 1; j <= P->n; j++)

       {  GLPCOL *col = P->col[j];

          if (col->type == GLP_DB && col->lb >= col->ub)

          {  if (parm->msg_lev >= GLP_MSG_ERR)

                xprintf("glp_intopt: column %d: lb = %g, ub = %g; incorr"

                   "ect bounds\n", j, col->lb, col->ub);

             ret = GLP_EBOUND;

             goto done;

          }

       }

       /* bounds of all integer variables must be integral */

       for (j = 1; j <= P->n; j++)

       {  GLPCOL *col = P->col[j];

          if (col->kind != GLP_IV) continue;

          if (col->type == GLP_LO || col->type == GLP_DB)

          {  if (col->lb != floor(col->lb))

             {  if (parm->msg_lev >= GLP_MSG_ERR)

                   xprintf("glp_intopt: integer column %d has non-intege"

                      "r lower bound %g\n", j, col->lb);

                ret = GLP_EBOUND;

                goto done;

             }

          }

          if (col->type == GLP_UP || col->type == GLP_DB)

          {  if (col->ub != floor(col->ub))

             {  if (parm->msg_lev >= GLP_MSG_ERR)

                   xprintf("glp_intopt: integer column %d has non-intege"

                      "r upper bound %g\n", j, col->ub);

                ret = GLP_EBOUND;

                goto done;

             }

          }

          if (col->type == GLP_FX)

          {  if (col->lb != floor(col->lb))

             {  if (parm->msg_lev >= GLP_MSG_ERR)

                   xprintf("glp_intopt: integer column %d has non-intege"

                      "r fixed value %g\n", j, col->lb);

                ret = GLP_EBOUND;

                goto done;

             }

          }

       }

       /* solve MIP problem */

       if (parm->msg_lev >= GLP_MSG_ALL)

       {  int ni = glp_get_num_int(P);

          int nb = glp_get_num_bin(P);

          char s[50];

          xprintf("GLPK Integer Optimizer, v%s\n", glp_version());

          xprintf("%d row%s, %d column%s, %d non-zero%s\n",

             P->m, P->m == 1 ? "" : "s", P->n, P->n == 1 ? "" : "s",

             P->nnz, P->nnz == 1 ? "" : "s");

          if (nb == 0)

             strcpy(s, "none of");

          else if (ni == 1 && nb == 1)

             strcpy(s, "");

          else if (nb == 1)

             strcpy(s, "one of");

          else if (nb == ni)

             strcpy(s, "all of");

          else

             sprintf(s, "%d of", nb);

          xprintf("%d integer variable%s, %s which %s binary\n",

             ni, ni == 1 ? "" : "s", s, nb == 1 ? "is" : "are");

       }

 #if 1 /* 28/V-2010 */

       if (parm->alien)

       {  /* use alien integer optimizer */

          ret = _glp_intopt1(P, parm);

          goto done;

       }

 #endif

       if (!parm->presolve)

          ret = solve_mip(P, parm);

       else

          ret = preprocess_and_solve_mip(P, parm);

 done: /* return to the application program */

       return ret;

 }

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

 *  NAME

 *

 *  glp_init_iocp - initialize integer optimizer control parameters

 *

 *  SYNOPSIS

 *

 *  void glp_init_iocp(glp_iocp *parm);

 *

 *  DESCRIPTION

 *

 *  The routine glp_init_iocp initializes control parameters, which are

 *  used by the integer optimizer, with default values.

 *

 *  Default values of the control parameters are stored in a glp_iocp

 *  structure, which the parameter parm points to. */

 void glp_init_iocp(glp_iocp *parm)

 {     parm->msg_lev = GLP_MSG_ALL;

       parm->br_tech = GLP_BR_DTH;

       parm->bt_tech = GLP_BT_BLB;

       parm->tol_int = 1e-5;

       parm->tol_obj = 1e-7;

       parm->tm_lim = INT_MAX;

       parm->out_frq = 5000;

       parm->out_dly = 10000;

       parm->cb_func = NULL;

       parm->cb_info = NULL;

       parm->cb_size = 0;

       parm->pp_tech = GLP_PP_ALL;

       parm->mip_gap = 0.0;

       parm->mir_cuts = GLP_OFF;

       parm->gmi_cuts = GLP_OFF;

       parm->cov_cuts = GLP_OFF;

       parm->clq_cuts = GLP_OFF;

       parm->presolve = GLP_OFF;

       parm->binarize = GLP_OFF;

       parm->fp_heur = GLP_OFF;

 #if 1 /* 28/V-2010 */

       parm->alien = GLP_OFF;

 #endif

       return;

 }

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

 *  NAME

 *

 *  glp_mip_status - retrieve status of MIP solution

 *

 *  SYNOPSIS

 *

 *  int glp_mip_status(glp_prob *mip);

 *

 *  RETURNS

 *

 *  The routine lpx_mip_status reports the status of MIP solution found

 *  by the branch-and-bound solver as follows:

 *

 *  GLP_UNDEF  - MIP solution is undefined;

 *  GLP_OPT    - MIP solution is integer optimal;

 *  GLP_FEAS   - MIP solution is integer feasible but its optimality

 *               (or non-optimality) has not been proven, perhaps due to

 *               premature termination of the search;

 *  GLP_NOFEAS - problem has no integer feasible solution (proven by the

 *               solver). */

 int glp_mip_status(glp_prob *mip)

 {     int mip_stat = mip->mip_stat;

       return mip_stat;

 }

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

 *  NAME

 *

 *  glp_mip_obj_val - retrieve objective value (MIP solution)

 *

 *  SYNOPSIS

 *

 *  double glp_mip_obj_val(glp_prob *mip);

 *

 *  RETURNS

 *

 *  The routine glp_mip_obj_val returns value of the objective function

 *  for MIP solution. */

 double glp_mip_obj_val(glp_prob *mip)

 {     /*struct LPXCPS *cps = mip->cps;*/

       double z;

       z = mip->mip_obj;

       /*if (cps->round && fabs(z) < 1e-9) z = 0.0;*/

       return z;

 }

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

 *  NAME

 *

 *  glp_mip_row_val - retrieve row value (MIP solution)

 *

 *  SYNOPSIS

 *

 *  double glp_mip_row_val(glp_prob *mip, int i);

 *

 *  RETURNS

 *

 *  The routine glp_mip_row_val returns value of the auxiliary variable

 *  associated with i-th row. */

 double glp_mip_row_val(glp_prob *mip, int i)

 {     /*struct LPXCPS *cps = mip->cps;*/

       double mipx;

       if (!(1 <= i && i <= mip->m))

          xerror("glp_mip_row_val: i = %d; row number out of range\n", i)

             ;

       mipx = mip->row[i]->mipx;

       /*if (cps->round && fabs(mipx) < 1e-9) mipx = 0.0;*/

       return mipx;

 }

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

 *  NAME

 *

 *  glp_mip_col_val - retrieve column value (MIP solution)

 *

 *  SYNOPSIS

 *

 *  double glp_mip_col_val(glp_prob *mip, int j);

 *

 *  RETURNS

 *

 *  The routine glp_mip_col_val returns value of the structural variable

 *  associated with j-th column. */

 double glp_mip_col_val(glp_prob *mip, int j)

 {     /*struct LPXCPS *cps = mip->cps;*/

       double mipx;

       if (!(1 <= j && j <= mip->n))

          xerror("glp_mip_col_val: j = %d; column number out of range\n",

             j);

       mipx = mip->col[j]->mipx;

       /*if (cps->round && fabs(mipx) < 1e-9) mipx = 0.0;*/

       return mipx;

 }

 /* eof */