ascend4/solver/slv9.c

/*
 *  Conditional Modeling Solver
 *  by Vicente Rico-Ramirez
 *  Version: $Revision: 1.22 $
 *  Version control file: $RCSfile: slv9.c,v $
 *  Date last modified: $Date: 2000/01/25 02:27:58 $
 *  Last modified by: $Author: ballan $
 *
 *  This file is part of the SLV solver.
 *
 *  The SLV solver 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 2 of the
 *  License, or (at your option) any later version.
 *
 *  The SLV solver is distributed in 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 the program; if not, write to the Free Software Foundation,
 *  Inc., 675 Mass Ave, Cambridge, MA 02139 USA.  Check the file named
 *  COPYING.  COPYING is found in ../compiler.
 *
 */

#include <math.h>
#include "utilities/ascConfig.h"
#include "utilities/ascSignal.h"
#include "utilities/ascMalloc.h"
#include "general/tm_time.h"
#include "utilities/mem.h"
#include "compiler/compiler.h"
#include "compiler/instance_enum.h"
#include "general/list.h"
#include "compiler/fractions.h"
#include "compiler/dimen.h"
#include "compiler/functype.h"
#include "compiler/func.h"
#include "solver/mtx.h"
#include "solver/mtx_reorder.h"
#include "solver/linsol.h"
#include "solver/linsolqr.h"
#include "solver/slv_types.h"
#include "solver/var.h"
#include "solver/rel.h"
#include "solver/discrete.h"
#include "solver/conditional.h"
#include "solver/logrel.h"
#include "solver/bnd.h"
#include "solver/calc.h"
#include "solver/relman.h"
#include "solver/logrelman.h"
#include "solver/bndman.h"
#include "solver/cond_config.h"
#include "solver/slv_common.h"
#include "solver/slv_client.h"
#include "solver/conopt.h"
#include "solver/slv9.h"
#include "solver/slv_stdcalls.h"
#include "solver/slvDOF.h"


#if !defined(STATIC_CMSLV) && !defined(DYNAMIC_CMSLV)
int slv9_register(SlvFunctionsT *f)
{
  (void)f;  /* stop gcc whining about unused parameter */

  FPRINTF(ASCERR,"CMSlv not compiled in this ASCEND IV.\n");
  return 1;
}
#else /* either STATIC_CMSLV or DYNAMIC_CMSLV is defined */

#ifdef DYNAMIC_CMSLV
/* do dynamic loading stuff.   yeah, right */

#else /* following is used if STATIC_CMSLV is defined */


/*
 * definitions to enable/disable the output of partial results in
 * the solution of a problem
 */
#define DEBUG FALSE
#define SHOW_LOGICAL_DETAILS FALSE
#define SHOW_BOUNDARY_ANALYSIS_DETAILS FALSE
#define SHOW_OPTIMIZATION_DETAILS FALSE
#define SHOW_BISECTION_DETAILS FALSE
#define SHOW_LINEAR_SEARCH_DETAILS FALSE
#define SHOW_LAGRANGE_DETAILS FALSE
#define DEBUG_CONSISTENCY FALSE
#define TEST_CONSISTENCY FALSE
#define USE_CONSISTENCY FALSE

/*
 * Is CONOPT  available ?
 */
#if defined(STATIC_CONOPT)

#define CONOPT_ACTIVE TRUE
#else  /* defined(STATIC_CONOPT) */
#define CONOPT_ACTIVE FALSE
#endif /* defined(STATIC_CONOPT) */

/*
 * system definitions
 */
#define SLV9(s) ((slv9_system_t)(s))
#define SERVER (sys->slv)
#define slv9_PA_SIZE 26 /* MUST INCREMENT WHEN ADDING PARAMETERS */
#define LOGSOLVER_OPTION_PTR (sys->parm_array[0])
#define LOGSOLVER_OPTION  ((*(char **)LOGSOLVER_OPTION_PTR))
#define NONLISOLVER_OPTION_PTR (sys->parm_array[1])
#define NONLISOLVER_OPTION  ((*(char **)NONLISOLVER_OPTION_PTR))
#define OPTSOLVER_OPTION_PTR (sys->parm_array[2])
#define OPTSOLVER_OPTION  ((*(char **)OPTSOLVER_OPTION_PTR))
#define TIME_LIMIT_PTR (sys->parm_array[3])
#define TIME_LIMIT     ((*(int32 *)TIME_LIMIT_PTR))
#define ITER_LIMIT_PTR (sys->parm_array[4])
#define ITER_LIMIT     ((*(int32 *)ITER_LIMIT_PTR))
#define ITER_BIS_LIMIT_PTR (sys->parm_array[5])
#define ITER_BIS_LIMIT  ((*(int32 *)ITER_BIS_LIMIT_PTR))
#define TOO_SMALL_PTR (sys->parm_array[6])
#define TOO_SMALL     ((*(real64 *)TOO_SMALL_PTR))
#define LINEAR_SEARCH_FACTOR_PTR (sys->parm_array[7])
#define LINEAR_SEARCH_FACTOR  ((*(real64 *)LINEAR_SEARCH_FACTOR_PTR))
#define SHOW_MORE_IMPT_PTR (sys->parm_array[8])
#define SHOW_MORE_IMPT     ((*(int32 *)SHOW_MORE_IMPT_PTR))
#define SHOW_LESS_IMPT_PTR (sys->parm_array[9])
#define SHOW_LESS_IMPT     ((*(int32 *)SHOW_LESS_IMPT_PTR))
#define AUTO_RESOLVE_PTR (sys->parm_array[10])
#define AUTO_RESOLVE     ((*(int32 *)AUTO_RESOLVE_PTR))
#define UNDEFINED_PTR (sys->parm_array[11])
#define UNDEFINED  ((*(real64 *)UNDEFINED_PTR))
#define DOMLIM_PTR (sys->parm_array[12])
#define DOMLIM     ((*(int32 *)DOMLIM_PTR))
#define OPT_ITER_LIMIT_PTR (sys->parm_array[13])
#define OPT_ITER_LIMIT     ((*(int32 *)OPT_ITER_LIMIT_PTR))
#define INFINITY_PTR (sys->parm_array[14])
#define INFINITY  ((*(real64 *)INFINITY_PTR))
#define OBJ_TOL_PTR (sys->parm_array[15])
#define OBJ_TOL  ((*(real64 *)OBJ_TOL_PTR))
#define RTMAXJ_PTR (sys->parm_array[16])
#define RTMAXJ     ((*(real64 *)RTMAXJ_PTR))
#define RHO_PTR (sys->parm_array[17])
#define RHO     ((*(real64 *)RHO_PTR))


/*
 * Client tokens of the different solvers: Conditional, Optimizer,
 * Nonlinear, Logical. We will switch from one client token to
 * another as the solution process occurs.
 */
#define NUMBER_OF_CLIENTS  4
SlvClientToken  token[NUMBER_OF_CLIENTS];
int32 solver_index[NUMBER_OF_CLIENTS];

/*
 * indeces in arrays token and solver_index
 */
#define CONDITIONAL_SOLVER  0
#define LOGICAL_SOLVER      1
#define NONLINEAR_SOLVER    2
#define OPTIMIZATION_SOLVER 3

/*
 * Do we have an optimization problem ?.  Global variable initialized
 * to 0 (not optimizing)
 */
static int32 g_optimizing = 0;

#if USE_CONSISTENCY
/*
 * number of subregion visited during the solution of the conditional
 * model.
 */
static int32 g_subregions_visited;

#endif /* USE_CONSISTENCY */


/* auxiliar structures */
struct boolean_values {
  int32            *pre_val;    /* previous values of dis_discrete */
  int32            *cur_val;    /* current values of dis_discrete  */
};

struct matching_cases {
  int32            *case_list;      /* list of cases */
  int32            ncases;          /* number of cases */
  int32            diff_subregion;  /* subregion ? */
};

struct real_values {
  real64           *pre_values;     /* previous values of var_variables */
  real64           *cur_values;     /* current values of var_variables */
};

struct opt_vector {
  real64 *element;                  /* elements in colum of matrix */
};

struct opt_matrix {
  struct opt_vector *cols;          /* columns in matrix */
};

struct subregionID {
  unsigned long    ID_number;
  int32            *bool_values;
};

struct ds_subregion_list {
   int32 length,capacity;
   struct subregionID *sub_stack;
};

struct ds_subregions_visited {
   int32 length,capacity;
   unsigned long *visited;
};

/*
 * This solver's data structure (CMSlv)
 */
struct slv9_system_structure {

  /*
   *  Problem definition
   */
  slv_system_t       slv;           /* slv_system_t back-link */

  struct rel_relation    *obj;          /* Objective function: NULL = none */
  struct var_variable    **vlist;       /* Variable list (NULL terminated) */
  struct rel_relation    **rlist;       /* Relation list (NULL terminated) */
  struct dis_discrete    **dvlist;      /* Dis vars list (NULL terminated) */
  struct logrel_relation **lrlist;      /* Logrels list(NULL terminated)*/
  struct bnd_boundary    **blist;       /* Variable list (NULL terminated) */
  struct var_variable    **mvlist;      
  struct dis_discrete    **mdvlist;     /* We will not touch the masters list,
                     * but they can provide very useful
                     * information to the conditional
                     * solver since the master index does
                     * not change.
                                         */

  /*
   * for optimization at boundaries
   */
  struct opt_matrix      *coeff_matrix; /* Matrix for optimization problem */
  struct opt_vector      *opt_var_values; /* Values of vars in opt problem */
  int32                  subregions;    /* number of subregions at cur bnd */
  mtx_matrix_t           lin_mtx;       /* Matrix to define the linear system
                     * for calculation of the lagrange
                     * multipliers
                     */
  /*
   * For search consistency analysis
   */
   struct ds_subregion_list subregion_list;
                                        /* 
                     * Information about the subregions
                     * visited during the solution of the
                     * conditional model
                     */
   struct ds_subregions_visited subregions_visited;
                                        /* 
                     * ID number of the subregions 
                     * visited 
                     */
   int32            *bool_mindex;       /* master indices of boolean vars in
                     * the problem associated with WHENs 
                     */
   int32 need_consistency_analysis;    /* Is the consistency analysis needed */

 
  /*
   *  Solver information
   */
  int32                  integrity;     /* Has the system been created ? */
  int32                  presolved;     /* Has the system been presolved ? */
  slv_parameters_t       p;             /* Parameters */
  slv_status_t           s;             /* Status (as of iteration end) */
  int32                  cap;           /* Order of matrix/vectors */
  int32                  rank;          /* Symbolic rank of problem */
  int32                  vused;         /* Free and incident variables */
  int32                  vtot;          /* length of varlist */
  int32                  mvtot;         /* length of master varlist */
  int32                  rused;         /* Included relations */
  int32                  rtot;          /* length of rellist */
  real64                 clock;         /* CPU time */
  int32                  nliter;        /* iterations in nonlinear solver */

  void *parm_array[slv9_PA_SIZE];     /* array of pointers to param values */
  struct slv_parameter pa[slv9_PA_SIZE]; /* &pa[0] => sys->p.parms */

  /*
   *  Data for optimizer at boundaries (CONOPT)
   */
  struct conopt_data con;
};


/*
 *  Integrity checks
 *  ----------------
 *     check_system(sys)
 */

#define OK        ((int32)813029392)
#define DESTROYED ((int32)103289182)

/*
 *  Checks sys for NULL and for integrity.
 */
static int check_system(slv9_system_t sys)
{
  if( sys == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) check_system\n");
    FPRINTF(ASCERR,"        NULL system handle.\n");
    return 1;
  }

  switch( sys->integrity ) {
  case OK:
    return 0;
  case DESTROYED:
    FPRINTF(ASCERR,"ERROR:  (slv9) check_system\n");
    FPRINTF(ASCERR,"        System was recently destroyed.\n");
    return 1;
  default:
    FPRINTF(ASCERR,"ERROR:  (slv9) check_system\n");
    FPRINTF(ASCERR,"        System reused or never allocated.\n");
    return 1;
  }
}


/*
 *  General input/output routines
 *  -----------------------------
 *     print_var_name(out,sys,var)
 */
#define print_var_name(a,b,c) slv_print_var_name((a),(b)->slv,(c))


/*
 *  Array operations
 *  ----------------
 *     destroy_array(p)
 *     create_array(len,type)
 *     create_zero_array(len,type)
 */
#define destroy_array(p)  \
   if( (p) != NULL ) ascfree((p))
#define create_array(len,type)  \
   ((len) > 0 ? (type *)ascmalloc((len)*sizeof(type)) : NULL)
#define create_zero_array(len,type)  \
   ((len) > 0 ? (type *)asccalloc((len),sizeof(type)) : NULL)


/*
 *  Search Consistency Analysis during iterative process
 *  ---------------------------------------------------------
 *  The caller of this functions is in charge of 
 *  defining the extension of the analysis by passing an integer
 *  which will tell us if 1) the analysis consider only the current 
 *  and the previous alternatives or 2) the analysis consider all the
 *  alternatives visited at current the state of the solution 
 *  algorithm.
 */

  /*
   * Handling dynamic allocation of the structural information
   */

#define alloc_array(nelts,type)   \
   ((nelts) > 0 ? (type *)ascmalloc((nelts)*sizeof(type)) : NULL)
#define copy_nums(from,too,nnums)  \
   asc_memcpy((from),(too),(nnums)*sizeof(int32))
#define copy_subregions(from,too,nsubs)  \
   asc_memcpy((from),(too),(nsubs)*sizeof(struct subregionID))

/*
 *  Appends the subregion_visited into the list
 */
static void append_subregion(struct ds_subregion_list *sl, 
                 struct subregionID sub)
{
  if( sl->length == sl->capacity ) {
    int32 newcap;
    struct subregionID *newlist;

    newcap = sl->capacity + 10;
    newlist = alloc_array(newcap,struct subregionID);
    copy_subregions((char *)sl->sub_stack,(char *)newlist,sl->length);
    if( sl->sub_stack != NULL ) {
      ascfree(sl->sub_stack);
    }
    sl->sub_stack = newlist;
    sl->capacity = newcap;
  }

  sl->sub_stack[sl->length++] = sub;
}

/*
 *  Appends the subregion_visited into the list
 */
static void append_sub_visited(struct ds_subregions_visited *sv,
                   unsigned long sub_visited)
{
  if( sv->length == sv->capacity ) {
    int32 newcap;
    unsigned long *newlist;

    newcap = sv->capacity + 10;
    newlist = alloc_array(newcap,unsigned long);
    copy_nums((char *)sv->visited,(char *)newlist,sv->length);
    if( sv->visited != NULL ) {
      ascfree(sv->visited);
    }
    sv->visited = newlist;
    sv->capacity = newcap;
  }

  sv->visited[sv->length++] = sub_visited;
}

static unsigned long powoftwo (int32 expo)
{
  unsigned long val;
  int32 c;
 
  val = 1;
  for (c=1; c<= expo; c++) {
    val = val * 2;
  }

  return val;
}


/*
 * Storage information (boolean values) about a subregion so that
 * we can visit it later for interactive strucutral analysis
 */
static void ID_and_storage_subregion_information(slv_system_t server,
                         SlvClientToken asys)
{
  slv9_system_t sys;
  struct dis_discrete **bvlist;
  struct dis_discrete *cur_dis;
  struct ds_subregion_list *sl;
  struct ds_subregions_visited *sv; 
  struct subregionID *sub;
  dis_filter_t dfilter;
  unsigned long val, visited, sID;
  int32 d, numdvs, numdvf, dcount;
  int32 len, s, found;

  sys = SLV9(asys);
  check_system(sys);

  bvlist = sys->mdvlist;
  if(bvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR: ID_and_storage_subregion_information.\n");
    FPRINTF(ASCERR,"        Master discrete var list was never set.\n");
    return;
  }
  numdvs = slv_get_num_master_dvars(server);

  dfilter.matchbits = (DIS_INWHEN | DIS_BOOLEAN);
  dfilter.matchvalue = (DIS_INWHEN | DIS_BOOLEAN);
  numdvf = slv_count_master_dvars(server,&dfilter);

  if (numdvf > 0) {
    sub = (struct subregionID *)(ascmalloc(sizeof(struct subregionID)));
    sub->bool_values = (int32 *)(ascmalloc(numdvf*sizeof(int32)));
  } else {
    FPRINTF(ASCERR,"ERROR: ID_and_storage_subregion_information.\n");
    FPRINTF(ASCERR,"       No boolean variables in the problem \n");
    return;
  }

  dcount = 0;
  val = 0;
  for (d=0; d<numdvs; d++) {
    cur_dis = bvlist[d];
    if (dis_apply_filter(cur_dis,&dfilter)) {
      sub->bool_values[dcount] = dis_value(cur_dis);
      dcount++;
      if (sub->bool_values[dcount - 1] == 1) {
        val = val + powoftwo(numdvf - dcount);
      }
    }
  }
  if ( (val == 0 ) && (numdvf > 0) ) {
    val = powoftwo(numdvf);
  }
  sub->ID_number = val;
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"ID of alternative is %ul \n", val);
#endif /* DEBUG_CONSISTENCY */
  visited = val;
  found = 0;
  len = sys->subregions_visited.length;
  if (len > 0) {
    for (s=0; s<len; s++) {
      sID = sys->subregions_visited.visited[s];
      if (visited == sID) {
        found = 1;
        break;
      }
    }
  }

  sv = &(sys->subregions_visited);
  append_sub_visited(sv,visited);

  if (found == 0) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"Saving alternative\n");
#endif /* DEBUG_CONSISTENCY */
    sl = &(sys->subregion_list);
    append_subregion(sl,(*sub));
  } else {
    destroy_array(sub->bool_values);
    ascfree(sub);
  }

  return;
}

/*
 * Destroys subregion information
 */
static void destroy_subregion_information(SlvClientToken asys)
{
  slv9_system_t sys;
  struct subregionID *sub;
  int32 lens, s;

  sys = SLV9(asys);
  check_system(sys);

  if (sys->subregions_visited.visited != NULL) {
    destroy_array(sys->subregions_visited.visited);
  }

  lens = sys->subregion_list.length;
  if (lens != 0) {
    for (s=0; s<lens; s++) {
      sub = &(sys->subregion_list.sub_stack[s]);
      if (sub->bool_values != NULL) {
        destroy_array(sub->bool_values);
      }
    }
  }

  if (sys->subregion_list.sub_stack != NULL) {
    destroy_array(sys->subregion_list.sub_stack);
  }
  
  if (sys->bool_mindex != NULL) {
    destroy_array(sys->bool_mindex);
  }
}


/*
 * Storing original values of boolean variables
 */
static void store_original_bool_values(struct gl_list_t *bollist,
                             struct boolean_values *bval)
{
  struct dis_discrete *dvar;
  int32 d, dlen;

  dlen = gl_length(bollist);
  bval->pre_val = create_array(dlen,int32);
  bval->cur_val = create_array(dlen,int32);
  for (d=1; d<=dlen; d++){
    dvar = (struct dis_discrete *)gl_fetch(bollist,d);
    bval->cur_val[d-1] = dis_value(dvar);
    bval->pre_val[d-1] = dis_previous_value(dvar);
  }
}

/*
 * Restoring original values of boolean variables
 */
static void restore_original_bool_values(struct gl_list_t *bollist,
                               struct boolean_values *bval)
{
  struct dis_discrete *dvar;
  int32 d, dlen;

  dlen = gl_length(bollist);
  for (d=1; d<=dlen; d++){
    dvar = (struct dis_discrete *)gl_fetch(bollist,d);
    dis_set_boolean_value(dvar,bval->cur_val[d-1]);
    dis_set_value(dvar,bval->cur_val[d-1]);
    dis_set_previous_value(dvar,bval->pre_val[d-1]);
  }
  destroy_array(bval->cur_val);
  destroy_array(bval->pre_val);
}


/*
 * the first element of cur_cases is in position one. The result is
 * the same array, but ordered and starting in position zero
 */
static void cases_reorder(int32 *cur_cases, int32 *correct_cases, int32 ncases)
{
  int32 cur_case,pos,tmp_num,c,ind;

  for (c=1; c<=ncases; c++) {
    tmp_num = 0;
    for (ind=1; ind<=ncases; ind++) {
      cur_case = cur_cases[ind];
      if (tmp_num < cur_case) {
        pos = ind;
        tmp_num  = cur_case;
      }
    }
    cur_cases[pos] = 0;
    correct_cases[ncases-c] = tmp_num;
  }

  return;
}

/*
 * Restoring orignal configuration of the system
 */
static void restore_configuration(slv_system_t server, 
                  struct gl_list_t *bollist)

{
  int32 *cur_cases, *correct_cases;
  int32 ncases;

   cur_cases = cases_matching(bollist,&ncases);
   correct_cases = create_array(ncases,int32);
   cases_reorder(cur_cases,correct_cases,ncases);
   set_active_rels_in_subregion(server,correct_cases,ncases,bollist);
   set_active_vars_in_subregion(server);
   destroy_array(cur_cases);
   destroy_array(correct_cases);
}


/*
 * Get the list of boolean variables in the problem which are
 * associated with a WHEN
 */
static struct gl_list_t *get_list_of_booleans(slv_system_t server,
                          SlvClientToken asys)
{
  slv9_system_t sys;
  struct dis_discrete **bvlist;
  struct dis_discrete *cur_dis;
  struct gl_list_t *boolvars;
  dis_filter_t dfilter;
  int32 numdvf, numdvs, d, dcount;

  sys = SLV9(asys);
  check_system(sys);

  bvlist = sys->mdvlist;
  if(bvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) get_list_of_booleans.\n");
    FPRINTF(ASCERR,"        Master discrete var list was never set.\n");
    return NULL;
  }
  numdvs = slv_get_num_master_dvars(server);

  dfilter.matchbits = (DIS_INWHEN | DIS_BOOLEAN);
  dfilter.matchvalue = (DIS_INWHEN | DIS_BOOLEAN);
  numdvf = slv_count_master_dvars(server,&dfilter);

  if (numdvf == 0) {
    FPRINTF(ASCERR,"ERROR: (slv9) get_list_of_booleans.\n");
    FPRINTF(ASCERR,"       No boolean variables in the problem \n");
    return NULL;
  }

  sys->bool_mindex = (int32 *)(ascmalloc(numdvf*sizeof(int32)));
  boolvars = gl_create(numdvf);
 
  dcount = 0;
  for (d=0; d<numdvs; d++) {
    cur_dis = bvlist[d];
    if (dis_apply_filter(cur_dis,&(dfilter))) {
      gl_append_ptr(boolvars,cur_dis);
      sys->bool_mindex[dcount] = d;
      dcount++;
    }
  }

  return boolvars;
}


/*
 * Get the eligible var list for each alternative
 * Return:
 * 1 means everything went right
 * 0 means the analysis has failed with the current parititioning
 * -1 means a memory problem has occurred
 */
static int32 get_eligible_set(slv_system_t server,struct gl_list_t *disvars,
                  int32 *terminate)
{
  struct var_variable **vslist;
  struct var_variable **vmlist;
  struct var_variable *mvar, *svar;
  var_filter_t vfilter;
  int32 *cur_cases;
  int32 *correct_cases;
  int32 *vars;
  int32 v, count, ind;
  int32 ncases;
  int32 mnum;
  int32 status,dof;

  vslist = slv_get_solvers_var_list(server);
  vmlist = slv_get_master_var_list(server);
  mnum = slv_get_num_master_vars(server);
  for (v=0; v<mnum; v++) {
    mvar = vmlist[v];
    var_set_eligible_in_subregion(mvar,FALSE);
  } 

  cur_cases = cases_matching(disvars,&ncases);
  correct_cases = create_array(ncases,int32);
  cases_reorder(cur_cases,correct_cases,ncases);
  set_active_rels_in_subregion(server,correct_cases,ncases,disvars);
  set_active_vars_in_subregion(server);
  destroy_array(cur_cases);
  destroy_array(correct_cases);

#if DEBUG_CONSISTENCY
  FPRINTF(ASCERR,"Analyzing alternative:\n");
#endif /* DEBUG_CONSISTENCY */

  if (!slvDOF_status(server,(&status),(&dof))) {
   FPRINTF(ASCERR,"ERROR in combinatorial search\n");
   FPRINTF(ASCERR,"Combinatorial search aborted\n");
   return -1;
  } else {
    if (status == 3) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"Alternative is structurally singular\n");
#endif /* DEBUG_CONSISTENCY */
      (*terminate) = 0;
      return 0;
    } else {
      if (status == 4) {
#if DEBUG_CONSISTENCY
         FPRINTF(ASCERR,"Alternative is overspecified\n");
#endif /* DEBUG_CONSISTENCY */
         (*terminate) = 0;
         return 0;
      }
    }
  }

  if (status == 1) {
    (*terminate) = 0;
#if DEBUG_CONSISTENCY
    FPRINTF(ASCERR,"Alternative has % d degrees of freedom.\n", dof);

#endif /* DEBUG_CONSISTENCY */
    if (slvDOF_eligible(server,&(vars))) {
      count = 0;
      while (vars[count] != -1) {
        ind = vars[count];
        svar = vslist[ind];
        v = var_mindex(svar);
        mvar = vmlist[v];
        var_set_eligible_in_subregion(mvar,TRUE);
        count++;
      }
      destroy_array(vars);   
    }
    if (dof > count) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,
              "Alternative does not have enough number of eligible vars\n");
#endif /* DEBUG_CONSISTENCY */
      return 0;
    }
  }

  if (status == 2) {
#if DEBUG_CONSISTENCY
    FPRINTF(ASCERR,"Alternative is square.\n");
#endif /* DEBUG_CONSISTENCY */
  }

  vfilter.matchbits = (VAR_ACTIVE | VAR_INCIDENT | VAR_SVAR
               | VAR_ELIGIBLE_IN_SUBREGION);
  vfilter.matchvalue = (VAR_ACTIVE | VAR_INCIDENT | VAR_SVAR);

  for (v=0; v<mnum; v++) {
    mvar = vmlist[v];
    if(var_apply_filter(mvar,&vfilter)) {
      var_set_eligible(mvar,FALSE);
    }
    var_set_eligible_in_subregion(mvar,FALSE);
  }   

  return 1;
}

/*
 * Get the eligible set of variables for each of the alternatives generated
 * by modifying the values of the boolean variables with the values stored
 * during the solution process
 * Return:
 * 1 means everything went right
 * 0 means the analysis has failed with the current partitioning
 * -1 means a memory problem or wierdness has occurred
 */
static int32 do_search_alternatives(slv_system_t server, SlvClientToken asys,
                    struct gl_list_t *disvars,
                    int32 *terminate, int32 all_sub)
{
  slv9_system_t sys;
  struct dis_discrete *cur_dis;
  struct subregionID *sub;
  int32 *values;
  int32 dlen, test;
  int32 lens, lenv, v, s, d;
  int32 result;
  unsigned long visited, vID;


  sys = SLV9(asys);

  dlen = gl_length(disvars);
  lenv = sys->subregions_visited.length;
  lens = sys->subregion_list.length; 

  if (all_sub == 0) { /* current and previous subregion */
    for (v=lenv-2; v<lenv; v++) {
      test = 0;
      vID = sys->subregions_visited.visited[v];
      for (s=lens-1; s>=0; s--) {
        sub = &(sys->subregion_list.sub_stack[s]);
        visited = sub->ID_number;
        if (vID == visited) {
          values = sub->bool_values;
          test = 1;
          FPRINTF(ASCERR,"s = %d \n",s);
          break;
    }
      }

      if (test == 0) {
        FPRINTF(ASCERR,"ERROR:  (slv9) do_search_alternatives \n");
        FPRINTF(ASCERR,"         subregion not found \n");
        return -1;
      }
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"Alternative = %ul \n", vID);
#endif /* DEBUG_CONSISTENCY */
      for (d=0; d<dlen; d++) {
        cur_dis = (struct dis_discrete *)(gl_fetch(disvars,d+1));
     if (values[d] == 1) {
           dis_set_boolean_value(cur_dis,TRUE);
     } else {
           dis_set_boolean_value(cur_dis,FALSE);
     }
      }
      result = get_eligible_set(server,disvars,terminate);
      if (result != 1) {
        return result;
      }
    }

  } else { /* all visited subregions */

    for (s=lens-1; s>=0; s--) {
      sub = &(sys->subregion_list.sub_stack[s]);
      values = sub->bool_values;
      vID = sub->ID_number;
#if DEBUG_CONSISTENCY
    FPRINTF(ASCERR,"Alternative = %ul \n", vID);
#endif /* DEBUG_CONSISTENCY */
      for (d=0; d<dlen; d++) {
        cur_dis = (struct dis_discrete *)(gl_fetch(disvars,d+1));
        if (values[d] == 1) {
          dis_set_boolean_value(cur_dis,TRUE);
    } else {
          dis_set_boolean_value(cur_dis,FALSE);
    }
      }
      result = get_eligible_set(server,disvars,terminate);
      if (result != 1) {
        return result;
      }
    }
  }

  return 1;
}


/*
 * Perform consistency analysis for the visited/current-previous subregions.
 * If all_subs is 1, the analysis takes in account all of the subregions 
 * visited by the solution algorithm at the current point if the solution
 * procedure. If all_subs is 0, the analysis is only for the current
 * and previous subregion.
 */
static int32 consistency(slv_system_t server, SlvClientToken asys,
             struct gl_list_t *bollist,
             int32 all_subs, int32 *terminate) 
{
  slv9_system_t sys;
  struct var_variable **vmlist;
  struct var_variable *mvar;
  var_filter_t vfilter;
  int32 *globeli;
  int32 dlen;
  int32 mnum, v, elnum;
  int32 result;
  int32 iter;

  sys = SLV9(asys);
  check_system(sys);

  /*
   * Initializing eligible bit for variables
   */
  vmlist = slv_get_master_var_list(server);
  mnum = slv_get_num_master_vars(server);
  for (v=0; v<mnum; v++) {
    mvar = vmlist[v];
    var_set_eligible(mvar,TRUE);
  } 

  dlen = gl_length(bollist);

#if DEBUG_CONSISTENCY
        FPRINTF(ASCERR,"S e a r c h i n g \n");
#endif /* DEBUG_CONSISTENCY */
  result = do_search_alternatives(server,asys,bollist,terminate,all_subs);

  if (result != 1) {
#if DEBUG_CONSISTENCY
    FPRINTF(ASCERR,"returning failed search after S e a r c h \n");
#endif /* DEBUG_CONSISTENCY */
    return result;
  }  

  /*
   * Getting the "globally" eligible variables
   */
  vfilter.matchbits = (VAR_INCIDENT | VAR_SVAR | VAR_ELIGIBLE | VAR_FIXED);
  vfilter.matchvalue = (VAR_INCIDENT | VAR_SVAR | VAR_ELIGIBLE);
  elnum = slv_count_master_vars(server,&vfilter);

  if (elnum > 0) {
    globeli = (int32 *)ascmalloc(elnum*sizeof(int32));
    elnum = 0;
    for (v=0; v<mnum; v++) {
      mvar = vmlist[v];
      if(var_apply_filter(mvar,&vfilter)) {
#if DEBUG_CONSISTENCY
        FPRINTF(ASCERR,"Eligible index = %d \n",v);
#endif /* DEBUG_CONSISTENCY */
        globeli[elnum] = v;
        elnum++;
      }
    }
  }

  /*
   * Recursively analysis
   */

  if ((*terminate) == 1) {
    if (elnum != 0) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"All alternatives are square but the \n");
      FPRINTF(ASCERR,"Eligible set is not null\n");
#endif /* DEBUG_CONSISTENCY */
      destroy_array(globeli);
    }
    return 1;
  } else {
    if (elnum == 0) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"No globally eligible variables to be fixed.\n");
#endif /* DEBUG_CONSISTENCY */
      return 0;
    }

    for (v=0; v<elnum; v++) {
      iter = 1;
      mvar = vmlist[globeli[v]];
      var_set_fixed(mvar,TRUE);
      var_set_potentially_fixed(mvar,TRUE);
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"Fixing index = %d \n",globeli[v]);
      FPRINTF(ASCERR,"N e s t e d   S e a r c h \n");
#endif /* DEBUG_CONSISTENCY */
      result = consistency(server,asys,bollist,all_subs,&iter);

      if (result != 1) {
#if DEBUG_CONSISTENCY
        FPRINTF(ASCERR,"%d eliminated\n",globeli[v]);
#endif /* DEBUG_CONSISTENCY */
        var_set_fixed(mvar,FALSE);
        var_set_potentially_fixed(mvar,FALSE);
        continue;
      } else {
        if (iter == 1) {
          (*terminate) = 1;
#if DEBUG_CONSISTENCY
          FPRINTF(ASCERR,"%d Acepted \n",globeli[v]);
#endif /* DEBUG_CONSISTENCY */
          destroy_array(globeli);
          return 1;
        } else {
          var_set_fixed(mvar,FALSE);
          var_set_potentially_fixed(mvar,FALSE);
          continue;
        }
      }
    }
    destroy_array(globeli);
#if DEBUG_CONSISTENCY
    FPRINTF(ASCERR,"returning 0 after nested search\n");
#endif /* DEBUG_CONSISTENCY */
    return 0;
  }
}


/*
 * Get a set of globally eligible variables. Eligible for all the subregions
 * visited, or for the previous and current subregions.
 */
static int32 get_globally_eligible(slv_system_t server, SlvClientToken asys,
                       struct gl_list_t *bollist,
                       int32 all_subs, int32 **eliset) 
{
  slv9_system_t sys;
  struct var_variable **vmlist;
  struct var_variable *mvar;
  var_filter_t vfilter;
  int32 dlen;
  int32 mnum, v, elnum;
  int32 terminate;
  int32 result;

  sys = SLV9(asys);
  check_system(sys);
  /*
   * Initializing eligible bit for variables
   */
  vmlist = slv_get_master_var_list(server);
  mnum = slv_get_num_master_vars(server);
  for (v=0; v<mnum; v++) {
    mvar = vmlist[v];
    var_set_eligible(mvar,TRUE);
  } 
  
  dlen = gl_length(bollist);

  /*
   * initializing
   */ 
  *eliset = NULL;
  terminate = 1;

#if DEBUG_CONSISTENCY
        FPRINTF(ASCERR,"S e a r c h i n g \n");
#endif /* DEBUG_CONSISTENCY */
  result = do_search_alternatives(server,asys,bollist,&terminate,all_subs);

  if (result != 1) {
    if (terminate == 0) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"ERROR: some alternatives are either singular or\n");
      FPRINTF(ASCERR,"overspecified. All the alternatives have to be\n");
      FPRINTF(ASCERR,
          "either square or underspecified to complete the analysis\n");
#endif /* DEBUG_CONSISTENCY */
    }
    return 0;
  }

  /*
   * Getting the "globally" eligible variables
   */
  vfilter.matchbits = (VAR_INCIDENT | VAR_SVAR | VAR_ELIGIBLE | VAR_FIXED);
  vfilter.matchvalue = (VAR_INCIDENT | VAR_SVAR | VAR_ELIGIBLE);
  elnum = slv_count_master_vars(server,&vfilter);

  *eliset = (int32 *)ascmalloc((elnum+1)*sizeof(int32));
  elnum = 0;
  for (v=0; v<mnum; v++) {
    mvar = vmlist[v];
    if(var_apply_filter(mvar,&vfilter)) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"Eligible index = %d \n",v);
      FPRINTF(ASCERR,"Variable : \n");
      print_var_name(ASCERR,sys,mvar);
#endif /* DEBUG_CONSISTENCY */
      (*eliset)[elnum] = v;
      elnum++;
    }
  }
  (*eliset)[elnum] = -1;

  if (elnum == 0) {
    if (terminate == 0) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,
          "Some alternatives are underspecified, but there does\n");
      FPRINTF(ASCERR,"not exist a set of eligible variables consistent \n");
      FPRINTF(ASCERR,"with all the alternatives\n");
#endif /* DEBUG_CONSISTENCY */
    } else {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"All alternatives are already square\n");
#endif /* DEBUG_CONSISTENCY */
    }
    return 0;
  } else {
    if (terminate == 1) {
#if DEBUG_CONSISTENCY
      FPRINTF(ASCERR,"All alternatives are square but the \n");
      FPRINTF(ASCERR,"Eligible set is not null\n");
#endif /* DEBUG_CONSISTENCY */
    }
  }
  return 1;
}


/*
 * Store and restore values of the boolean variables of the problem
 * and calls for the the set of globally eligible variables.If all_subs
 * is 1, the analysis takes in account all of the subregions visited
 * by the solution algorithm at the current point if the solution
 * procedure. If all_subs is 0, the analysis is only for the current
 * and previous subregion.
 */
static int32 consistent_eligible_set_for_subregions(slv_system_t server,
                            SlvClientToken asys,
                                    int32 **vlist, 
                            int32 all_subs) 
{
  struct gl_list_t *blist;
  struct boolean_values bval;
  int32 result;

  if (server==NULL || vlist == NULL) {
    FPRINTF(ASCERR,
        "consistent_eligible_set_for_subregions called with NULL.\n");
    return 0;
  }

  blist = get_list_of_booleans(server,asys);

  if ( (blist == NULL) || (gl_length(blist) == 0) ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) consistent_eligible_set_for_subregions \n");
    FPRINTF(ASCERR,"        List of boolean vars could not be found\n");
    return 0;
  }

  store_original_bool_values(blist,&(bval));
  result = get_globally_eligible(server,asys,blist,all_subs,vlist);

  restore_original_bool_values(blist,&(bval));
  restore_configuration(server,blist);
  gl_destroy(blist);

  if (result == 1) {
    return 1;
  } else {
    return 0;
  }

}

/*
 * Store and restore values of the boolean variables of the problem
 * and calls for the consistency analysis of the subregions.If all_subs
 * is 1, the analysis takes in account all of the subregions visited
 * by the solution algorithm at the current point if the solution
 * procedure. If all_subs is 0, the analysis is only for the current
 * and previous subregion.
 */
static int32 analyze_subregions(slv_system_t server,SlvClientToken asys,
                int32 **vlist, int32 all_subs) 
{
  slv9_system_t sys;
  struct var_variable ** vmlist;
  struct var_variable *mvar;
  struct gl_list_t *blist;
  struct boolean_values bval;
  var_filter_t vfilter;
  int32 mnum, elnum, v;
  int32 result;
  int32 terminate;

  sys = SLV9(asys);
  check_system(sys);

  if (server==NULL || vlist == NULL) {
    FPRINTF(ASCERR,"(slv9) analyze_subregions called with NULL.\n");
    return 0;
  }

  blist = get_list_of_booleans(server,asys);
  if ( (blist == NULL) || (gl_length(blist) == 0) ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) analyze_subregions \n");
    FPRINTF(ASCERR,"        List of boolean vars could not be found\n");
    return 0;
  }

  store_original_bool_values(blist,&(bval));
 /*
  * initializing
  */
  terminate = 1;
  (*vlist) = NULL;

  vmlist = slv_get_master_var_list(server);
  mnum = slv_get_num_master_vars(server);

  vfilter.matchbits = (VAR_POTENTIALLY_FIXED);
  vfilter.matchvalue = (VAR_POTENTIALLY_FIXED);

  result = consistency(server,asys,blist,all_subs,&terminate);

  if (result == 1) {
  /*
   * Getting the set of eligible variables
   */
    elnum = slv_count_master_vars(server,&vfilter);
    *vlist = (int32 *)ascmalloc((elnum+1)*sizeof(int32));
    elnum = 0;
    for (v=0; v<mnum; v++) {
      mvar = vmlist[v];
      if(var_apply_filter(mvar,&vfilter)) {
        var_set_fixed(mvar,FALSE);
        var_set_potentially_fixed(mvar,FALSE);
#if DEBUG_CONSISTENCY
        FPRINTF(ASCERR,"Variable in consistent set: \n");
        print_var_name(ASCERR,sys,mvar); 
#endif /* DEBUG_CONSISTENCY */
        (*vlist)[elnum] = v;
        elnum++;
      }
    }
    (*vlist)[elnum] = -1;

    restore_original_bool_values(blist,&(bval));
    restore_configuration(server,blist);
    gl_destroy(blist);
    return 1;
  } else {
    for (v=0; v<mnum; v++) {
      mvar = vmlist[v];
      if(var_apply_filter(mvar,&vfilter)) {
        var_set_fixed(mvar,FALSE);
        var_set_potentially_fixed(mvar,FALSE);
      }
    }
    restore_original_bool_values(blist,&(bval));
    restore_configuration(server,blist);
    gl_destroy(blist);
    return 0;
  }
}


/*
 * Finds the globally eligible set of variables only for the current and
 * previous subregions
 */
static int32 eligible_set_for_neighboring_subregions(slv_system_t server, 
                                SlvClientToken asys,
                            int32 **vlist) 
{
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->mdvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) eligible_set_for_neighboring_subregions\n");
    FPRINTF(ASCERR,"        Discrete Variable list was never set.\n");
    return 0;
  }

  if (!(sys->need_consistency_analysis)) {
    FPRINTF(ASCERR,"Globally eligible set not necessary\n");
    FPRINTF(ASCERR,"All the subregions have the same structure \n");
    return 0;
  }
 
  if (consistent_eligible_set_for_subregions(server,asys,vlist,0)) {
    return 1;
  }

  return 0;
}


/*
 * Perform the consistency analysis algorithm only for the current and
 * previous subregions
 */
static int32 consistency_for_neighboring_subregions(slv_system_t server, 
                                SlvClientToken asys,
                            int32 **vlist) 
{
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->mdvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) consistency_for_neighboring_subregions\n");
    FPRINTF(ASCERR,"        Discrete Variable list was never set.\n");
    return 0;
  }

  if (!(sys->need_consistency_analysis)) {
    FPRINTF(ASCERR,"consistency_analysis is not required\n");
    FPRINTF(ASCERR,"All the subregions have the same structure \n");
    return 0;
  }

  if (analyze_subregions(server,asys,vlist,0)) {
    return 1;
  }

  return 0;
}


/*
 * Consistency analysis for visisted subregions. This function 
 * gets the subregions that the solution algorithm has visited and 
 * analyzes them.
 */
static int32 eligible_set_for_subregions(slv_system_t server,
                     SlvClientToken asys,
                     int32 **vlist) 
{
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->mdvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) eligible_set_for_subregions \n");
    FPRINTF(ASCERR,"        Discrete Variable list was never set.\n");
    return 0;
  }

  if (!(sys->need_consistency_analysis)) {
    FPRINTF(ASCERR,"Globally eligible set not necessary \n");
    FPRINTF(ASCERR,"All the subregions have the same structure \n");
    return 0;
  }

  if (consistent_eligible_set_for_subregions(server,asys,vlist,1)) {
    return 1;
  }

  return 0;
}


/*
 * Consistency analysis for visisted subregions. This function 
 * gets the subregions that the solution algorithm has visited and 
 * analyzes them.
 */
static int32 consistency_analysis_for_subregions(slv_system_t server,
                             SlvClientToken asys,
                         int32 **vlist) 
{
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->mdvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) consistency_analysis_for_subregions\n");
    FPRINTF(ASCERR,"        Discrete Variable list was never set.\n");
    return 0;
  }

  if (!(sys->need_consistency_analysis)) {
    FPRINTF(ASCERR,"consistency_analysis is not required\n");
    FPRINTF(ASCERR,"All the subregions have the same structure \n");
    return 0;
  }

  if (analyze_subregions(server,asys,vlist,1)) {
    return 1;
  }

  return 0;
}


/*
 *  Handling of solution of the Logical Equations
 *  ---------------------------------------------------------
 *  This is made this way because it is a process which will be
 *  required very often.
 */

/*
 * Solution of the logical relations encountered in the system based on
 * the current values of the discrete variables.
 */
static void solve_logical_relations(slv_system_t server)
{
  slv_set_client_token(server,token[LOGICAL_SOLVER]);
  slv_set_solver_index(server,solver_index[LOGICAL_SOLVER]);
  slv_presolve(server);
#if SHOW_LOGICAL_DETAILS
  FPRINTF(ASCERR,"Solving Logical Relations\n");
#endif /* SHOW_LOGICAL_DETAILS  */
  slv_solve(server);
}


/*
 * Handling the modification of parameters in external solvers
 * ---------------------------------------------------------
 */

/*
 * different types of parameter values
 */
union param_value {
  int32 i;
  real64 r;
  int32 b;
  char *c;
};


/*
 * Setting the value of a parameter in a subsidiary solver
 */
static void set_param_in_solver(slv_system_t server, int32 solver,
                enum parm_type types, char *param,
                union param_value *value)
{
  slv_parameters_t p;
  int32 len,length;

  slv_set_client_token(server,token[solver]);
  slv_set_solver_index(server,solver_index[solver]);
  slv_get_parameters(server,&p);
  length = p.num_parms;
  for (len = 0; len < length; len++) {
    if (p.parms[len].type == types) {
      switch (p.parms[len].type) {
        case bool_parm:
          if (strcmp(param,p.parms[len].name) == 0) {
            p.parms[len].info.b.value = value->b;
          }
          break;
        case real_parm:
          if (strcmp(param,p.parms[len].name) == 0) {
            p.parms[len].info.r.value = value->r;
          }
          break;
        case char_parm:
          if (strcmp(param,p.parms[len].name) == 0) {
            p.parms[len].info.c.value = value->c;
          }
          break;
        case int_parm:
          if (strcmp(param,p.parms[len].name) == 0) {
            p.parms[len].info.i.value = value->i;
          }
          break;
        default:
          break;
      }
    }
  }
  return;
}


/*
 *  Analysis of Discrete Variables
 *  -------------------------------
 */

/*
 * Compare current values of the discrete variables with their previous values
 * in order to know if some of them have changed.
 */
static int32 some_dis_vars_changed(slv_system_t server, SlvClientToken asys)
{
  struct dis_discrete **dv, *cur_dis;
  int32 numdvs, ind;
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->dvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) some_dis_vars_changed\n");
    FPRINTF(ASCERR,"         Discrete variable list was never set.\n");
    return 0;
  }

  dv = sys->dvlist;
  numdvs = slv_get_num_solvers_dvars(server);
  for( ind = 0; ind < numdvs; ind++ ) {
    cur_dis = dv[ind];
#if SHOW_LOGICAL_DETAILS
    FPRINTF(ASCERR,"Boundary index = %d \n",ind);
    FPRINTF(ASCERR,"Current Value = %d\n",dis_value(cur_dis));
    FPRINTF(ASCERR,"Previous Value = %d\n",dis_previous_value(cur_dis));
#endif /* SHOW_LOGICAL_DETAILS */
    if ((dis_kind(cur_dis)==e_dis_boolean_t ) && dis_inwhen(cur_dis) ) {
      if (dis_value(cur_dis) != dis_previous_value(cur_dis)) {
        return 1;
      }
    }
  }
  return 0;
}

/*
 * Compare the original value of a discrete boolean variable (before
 * perturbation of boundaries) with its values after a solution
 * of the logical relations with some perturbed values for boundaries.
 * If those values are different, the bit VAL_MODIFIED is set to
 * TRUE. This will give us the boolean variable which will change as a
 * consequence of a boundary crossing.
 */
static void search_for_modified_dvars(struct dis_discrete **dv,
                      int32 numdvs,
                      struct boolean_values *bval)
{
  struct dis_discrete *cur_dis;
  int32 d;
  int32 orig_value;

  for (d=0; d<numdvs; d++) {
    cur_dis = dv[d];
    if(dis_inwhen(cur_dis) && dis_boolean(cur_dis)) {
      orig_value = bval->cur_val[d];
      if (orig_value != dis_value(cur_dis)) {
    dis_set_val_modified(cur_dis,TRUE);
      }
    }
  }
}


/*
 *  Analysis of Boundaries
 *  ----------------------------
 */

/*
 * Evaluates the current status (satisfied? , at zero?) of a boundary
 * and sets its flags accordingly. At the same time, it updates the
 * residual of the relation included in the boundary (see
 * bndman_calc_satisfied).
 */

static void update_boundaries(slv_system_t server, SlvClientToken asys)
{
  struct bnd_boundary **bp;
  int32 numbnds, ind, value;
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->blist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) update_boundaries.\n");
    FPRINTF(ASCERR,"         Boundary list was never set.\n");
    return;
  }

  bp = sys->blist;
  numbnds = slv_get_num_solvers_bnds(server);

  for( ind = 0; ind < numbnds; ++ind ) {
    value = bnd_status_cur(bp[ind]);
    bnd_set_pre_status(bp[ind],value);
    value = bndman_calc_satisfied(bp[ind]);
    bnd_set_cur_status(bp[ind],value);
    if ( (bnd_status_cur(bp[ind]) != bnd_status_pre(bp[ind])) &&
        bnd_kind(bp[ind]) == e_bnd_rel  && !bnd_at_zero(bp[ind])) {
      bnd_set_crossed(bp[ind],TRUE);
    } else {
      bnd_set_crossed(bp[ind],FALSE);
    }
    if (bnd_kind(bp[ind]) == e_bnd_rel) {
      value = bndman_calc_at_zero(bp[ind]);
      bnd_set_at_zero(bp[ind],value);
    } else {
      bnd_set_at_zero(bp[ind],FALSE);
    }
  }
}


/*
 * Look for some boundary with the CROSSED bit active. If this boundary
 * is used in some logical relation, the function returns 1, else returns 0
 */
static int32 some_boundaries_crossed(slv_system_t server, SlvClientToken asys)
{
  struct bnd_boundary **bp, *cur_bnd;
  int32 numbnds, ind;
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->blist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) some_boundaries_crossed\n");
    FPRINTF(ASCERR,"         Boundary list was never set.\n");
    return 0;
  }

  bp = sys->blist;
  numbnds = slv_get_num_solvers_bnds(server);
  for( ind = 0; ind < numbnds; ++ind ) {
    cur_bnd = bp[ind];
    if (bnd_crossed(cur_bnd) && bnd_in_logrel(cur_bnd)) {
      return 1;
    }
  }
  return 0;
}

/*
 * Look for some boundary with the AT_ZERO bit active.If this boundary
 * is used in some logical relation, the function returns 1, else returns 0
 */
static int32 some_boundaries_at_zero(slv_system_t server, SlvClientToken asys)
{
  struct bnd_boundary **bp, *cur_bnd;
  int32 numbnds, ind;
  slv9_system_t sys;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->blist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) some_boundaries_at_zero\n");
    FPRINTF(ASCERR,"         Boundary list was never set.\n");
    return 0;
  }

  bp = sys->blist;
  numbnds = slv_get_num_solvers_bnds(server);
  for( ind = 0; ind < numbnds; ++ind ) {
    cur_bnd = bp[ind];
    if (bnd_at_zero(cur_bnd) && bnd_in_logrel(cur_bnd)) {
      return 1;
    }
  }
  return 0;
}

/*
 * Perform the combinatorial perturbation of the boundaries which are
 * at their zero. That means: We are going to perform a combinatorial
 * search, changing the truth value of a SATISFIED term (for the
 * specified boundaries) ON and OFF, and finding the boolean variables
 * affected for those changes in value of the SATISFIED terms.
 */
static void do_perturbation_combinations(slv_system_t server,
                     struct boolean_values *bval,
                     struct bnd_boundary **bp,
                     struct dis_discrete **dv,
                     int32 numdvs,int32 *bndatzero,
                     int32 ind, int32 numbndf)
{
  slv_status_t status;
  int32 indpo;

  if(ind<(numbndf-1)) {
    indpo = ind + 1;
    bnd_set_perturb(bp[bndatzero[ind]],TRUE);
    do_perturbation_combinations(server,bval,bp,dv,numdvs,
                 bndatzero,indpo,numbndf);
    bnd_set_perturb(bp[bndatzero[ind]],FALSE);
    do_perturbation_combinations(server,bval,bp,dv,numdvs,
                 bndatzero,indpo,numbndf);
  } else {
    if (ind < numbndf) {
      bnd_set_perturb(bp[bndatzero[ind]],TRUE);
      solve_logical_relations(server);
      slv_get_status(server,&status);
      if(!status.converged) {
        FPRINTF(ASCERR,"WARNING: \n");
        FPRINTF(ASCERR,"(slv9) do_perturbation_combinations\n");
        FPRINTF(ASCERR," Not convergence in logical solver \n");
      } else {
        search_for_modified_dvars(dv,numdvs,bval);
      }
      bnd_set_perturb(bp[bndatzero[ind]],FALSE);
      solve_logical_relations(server);
      slv_get_status(server,&status);
      if(!status.converged) {
        FPRINTF(ASCERR,"WARNING: \n");
        FPRINTF(ASCERR,"(slv9) do_perturbation_combinations\n");
        FPRINTF(ASCERR," Not convergence in logical solver \n");
      } else {
        search_for_modified_dvars(dv,numdvs,bval);
      }
    } else {
      FPRINTF(ASCERR,"ERROR:  (slv9) do_perturbation_combinations\n");
      FPRINTF(ASCERR,"         Wrong boundary index as argument\n");
    }
  }
  return;
}


/*
 * Perform the combinatorial search of the subregions. That means:
 * We perform a combinatorial search, changing the value of the
 * discrete variables (given in disvars) TRUE and FALSE, and
 * finding which cases (in the WHENs) applies for each of the
 * combinations.
 */
static void do_dvar_values_combinations(struct gl_list_t *disvars,
                        struct matching_cases *cases,
                    int numdvf, int d,
                    int *pos_cases)
{
  struct dis_discrete *cur_dis;
  int32 *cur_cases;
  int32 ncases, dpo;

  if(d < numdvf) {
    dpo = d + 1;
    cur_dis = (struct dis_discrete *)(gl_fetch(disvars,d));
    dis_set_boolean_value(cur_dis,TRUE);
    do_dvar_values_combinations(disvars,cases,numdvf,dpo,pos_cases);
    dis_set_boolean_value(cur_dis,FALSE);
    do_dvar_values_combinations(disvars,cases,numdvf,dpo,pos_cases);
  } else {
    if (d == numdvf) {
      cur_dis = (struct dis_discrete *)(gl_fetch(disvars,d));
      dis_set_boolean_value(cur_dis,TRUE);
      cur_cases = cases_matching(disvars,&ncases);
      cases[(*pos_cases)].case_list = cur_cases;
      cases[(*pos_cases)].ncases = ncases;
      cases[(*pos_cases)].diff_subregion = 1;
      (*pos_cases)++;
      dis_set_boolean_value(cur_dis,FALSE);
      cur_cases = cases_matching(disvars,&ncases);
      cases[(*pos_cases)].case_list = cur_cases;
      cases[(*pos_cases)].ncases = ncases;
      cases[(*pos_cases)].diff_subregion = 1;
      (*pos_cases)++;
    } else {
      FPRINTF(ASCERR,"ERROR: (slv9) do_dvar_values_combinations\n");
      FPRINTF(ASCERR,"        Wrong discrete var index as argument\n");
    }
  }
  return;
}


/*
 * Orders of the elements of each array of cases,
 * so that we can compare them easier.
 */
static void order_case(int32 *case_list, int32 *newcaselist, int ncases)
{
  int32 cur_case,pos,tmp_num,c,ind;

  for (c=1; c<=ncases; c++) {
    tmp_num = 0;
    for (ind=1; ind<=ncases; ind++) {
      cur_case = case_list[ind];
      if (tmp_num < cur_case) {
        pos = ind;
        tmp_num  = cur_case;
      }
    }
    case_list[pos] = 0;
    newcaselist[ncases-c] = tmp_num;
  }
}


/*
 * Calls for the ordering of the elements of each array of cases,
 * so that we can compare them easier.
 */
static void order_cases(struct matching_cases *cases,int pos_cases)
{
  int32 *caselist;
  int32 cur_ncase,c;
  int32 *newcaselist;

  for (c=0; c<pos_cases;c++) {
    caselist  = cases[c].case_list;
    cur_ncase = cases[c].ncases;
    if (cur_ncase > 1) {
      newcaselist = create_array(cur_ncase,int32);
      order_case(caselist,newcaselist,cur_ncase);
      cases[c].case_list = newcaselist;
      destroy_array(caselist);
    } else {
      if (cur_ncase == 1) {
      newcaselist = create_array(1,int32);
      newcaselist[0] = caselist[1];
      cases[c].case_list = newcaselist;
      destroy_array(caselist);
      }
    }
  }

}


/*
 * Compare two arrays of cases (integer numbers). It returns 1 if they are
 * equal, else it returns 0.
 */
static int32 compare_case(int32 *cur_set, int32 *comp_set, int cur_ncases)
{
  int32 cur_case, comp_case, ind;

  for (ind=0; ind<cur_ncases; ind++) {
    cur_case = cur_set[ind];
    comp_case = comp_set[ind];
    if (cur_case != comp_case) {
      return 0;
    }
  }
  return 1;
}


/*
 * Compare the arrays of cases so that we can find the number of
 * different alternatives (subregions)
 */
static void compare_cases(struct matching_cases *cases,int pos_cases)
{
  int32 *cur_set, *comp_set, cur_ncases, comp_ncases;
  int32 c,d;

  for (c=0; c<pos_cases; c++) {
    cur_set = cases[c].case_list;
    cur_ncases = cases[c].ncases;
    if (cur_ncases == 0) {
      cases[c].diff_subregion = 0;
      continue;
    }
    for(d=0; d<c; d++) {
      comp_set = cases[d].case_list;
      comp_ncases = cases[d].ncases;
      if (cur_ncases != comp_ncases) {
        continue;
      } else {
        if (compare_case(cur_set,comp_set,cur_ncases)) {
          cases[c].diff_subregion = 0;
          break;
    }
      }
    }
  }
}


/*
 * Finds if my current point lies at a "real" boundary. By "real"
 * I mean a boundary which really causes a change in the
 * configuration. It returns 0 if the boundary at zero does not
 * affect the configuration. If the configuration is affected,
 * this function will find the number of subregions existing
 * for the current point as well as the cases (in WHENs) corresponding
 * to each of the subregions. At the end, the number of subregions is
 * n_subregions and the cases applying for each of them is stored
 * in the structure subregions.
 */
static int32 at_a_boundary(slv_system_t server, SlvClientToken asys,
                           int32 *n_subregions,
               struct matching_cases **subregions,
                   int32 *cur_subregion,
                           struct gl_list_t *disvars)
{
  slv9_system_t sys;
  struct bnd_boundary **bp, *cur_bnd;
  struct dis_discrete **dv, *cur_dis;
  struct boolean_values bval;
  dis_filter_t dfilter;
  bnd_filter_t bfilter;
  struct matching_cases *cases;
  int32 *bndatzero;
  int32 *dvarmodified;
  int32 *cur_cases;
  int32 *caselist, *newcaselist;
  int32 numbnds, numbndf, b, ind;
  int32 numdvs, numdvf, d;
  int32 cur_ncases, assign_cur_sub;
  int32 pos_cases, comb;
  char *param;
  union param_value u;

  sys = SLV9(asys);
  check_system(sys);

  if( sys->blist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) at_a_boundary\n");
    FPRINTF(ASCERR,"         Boundary list was never set.\n");
    return 0;
  }

  if( sys->dvlist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) at_a_boundary\n");
    FPRINTF(ASCERR,"         Discrete Variable list was never set.\n");
    return 0;
  }

  if (!some_boundaries_at_zero(server,asys)) {
    return 0;
  }

  bp = sys->blist;
  numbnds = slv_get_num_solvers_bnds(server);
  bfilter.matchbits = (BND_AT_ZERO);
  bfilter.matchvalue = (BND_AT_ZERO);
  numbndf = slv_count_solvers_bnds(server,&bfilter);
  bndatzero = create_array(numbndf,int32);
  ind = 0;
  for (b=0; b<numbnds; b++) {
    cur_bnd = bp[b];
    bnd_set_perturb(cur_bnd,FALSE);
    if (bnd_at_zero(cur_bnd)) {
#if SHOW_BOUNDARY_ANALYSIS_DETAILS
    FPRINTF(ASCERR,"boundary at zero = %d\n",b);
#endif /* SHOW_BOUNDARY_ANALYSIS_DETAILS */
      bndatzero[ind] = b;
      ind++;
    }
  }

  dv = sys->dvlist;
  numdvs = slv_get_num_solvers_dvars(server);
  bval.cur_val = create_array(numdvs,int32);
  bval.pre_val = create_array(numdvs,int32);

  for (d=0; d<numdvs; d++) {
    cur_dis = dv[d];
    dis_set_val_modified(cur_dis,FALSE);
    bval.cur_val[d] = dis_value(cur_dis);
    bval.pre_val[d] = dis_previous_value(cur_dis);
  }

#if SHOW_BOUNDARY_ANALYSIS_DETAILS
  FPRINTF(ASCERR,"Executing combinatorial perturbation of boundaries\n");
#endif /* SHOW_BOUNDARY_ANALYSIS_DETAILS */

  /*
   * Setting the value of the perturbation mode flag in the logical solver
   * to 1.
   * PERTURB_BOUNDARY is a boolean parameter of the logical solver
   * LRSlv. This parameter tells the solver whether it should change
   * the truth value of the SATISFIED terms or not (only for the
   * boundaries specified). This trick is important while finding
   * the number of subregions around a/several boundary(ies).
   */
  param = "perturbboundaries";
  u.b = 1;
  set_param_in_solver(server,LOGICAL_SOLVER,bool_parm,param,&u);

  ind = 0;
  do_perturbation_combinations(server,&(bval),bp,dv,numdvs,
                   bndatzero,ind,numbndf);
  /*
   * Setting the value of the perturbation mode flag in the logical solver
   * to 0.
   */
  u.b = 0;
  set_param_in_solver(server,LOGICAL_SOLVER,bool_parm,param,&u);

  destroy_array(bndatzero);

  dfilter.matchbits = (DIS_VAL_MODIFIED);
  dfilter.matchvalue = (DIS_VAL_MODIFIED);
  numdvf = slv_count_solvers_dvars(server,&dfilter);

  if (numdvf == 0) {
    FPRINTF(ASCERR,"Not really at a boundary\n");
    for (d=0; d<numdvs; d++) {
      cur_dis = dv[d];
      dis_set_boolean_value(cur_dis,bval.cur_val[d]);
      dis_set_value(cur_dis,bval.cur_val[d]);
      dis_set_previous_value(cur_dis,bval.pre_val[d]);
    }
    destroy_array(bval.cur_val);
    destroy_array(bval.pre_val);
    return 0;
  }

  dvarmodified = create_array(numdvf,int32);
  ind = 0;
  for (d=0; d<numdvs; d++) {
    cur_dis = dv[d];
    if(dis_val_modified(cur_dis)) {
      dvarmodified[ind] = d;
      gl_append_ptr(disvars,cur_dis);
      dis_set_val_modified(cur_dis,FALSE);
      ind++;
    }
  }

  for (d=0; d<numdvs; d++) {
    cur_dis = dv[d];
    dis_set_boolean_value(cur_dis,bval.cur_val[d]);
    dis_set_value(cur_dis,bval.cur_val[d]);
    dis_set_previous_value(cur_dis,bval.pre_val[d]);
  }

  pos_cases = 1;
  for (d = 1; d<=numdvf; d++) {
    pos_cases = pos_cases * 2;
  }

  cases = (struct matching_cases *)
                 (ascmalloc((pos_cases)*sizeof(struct matching_cases)));

#if SHOW_BOUNDARY_ANALYSIS_DETAILS
  FPRINTF(ASCERR,"Executing combinatorial search for subregions \n");
#endif /* SHOW_BOUNDARY_ANALYSIS_DETAILS */

  d = 1;
  comb = 0;
  do_dvar_values_combinations(disvars,cases,numdvf,d,&(comb));

  order_cases(cases,pos_cases);
  compare_cases(cases,pos_cases);

  (*n_subregions) = 0;
  for(comb=0; comb<pos_cases;comb++) {
    if(cases[comb].diff_subregion) {
      (*n_subregions)++;
    }
  }

  if ((*n_subregions)==0) {
    FPRINTF(ASCERR,"ERROR: at least one subregion must be found\n");
    for (d=0; d<numdvs; d++) {
      cur_dis = dv[d];
      dis_set_boolean_value(cur_dis,bval.cur_val[d]);
      dis_set_value(cur_dis,bval.cur_val[d]);
      dis_set_previous_value(cur_dis,bval.pre_val[d]);
    }
    destroy_array(bval.cur_val);
    destroy_array(bval.pre_val);
    for(comb=0; comb<pos_cases;comb++) {
      destroy_array(cases[comb].case_list);
    }
    destroy_array(cases);
    return 0;
  }

  if ((*n_subregions)==1) {
    FPRINTF(ASCERR,"Not really at a boundary\n");
    for (d=0; d<numdvs; d++) {
      cur_dis = dv[d];
      dis_set_boolean_value(cur_dis,bval.cur_val[d]);
      dis_set_value(cur_dis,bval.cur_val[d]);
      dis_set_previous_value(cur_dis,bval.pre_val[d]);
    }
    destroy_array(bval.cur_val);
    destroy_array(bval.pre_val);
    for(comb=0; comb<pos_cases;comb++) {
      destroy_array(cases[comb].case_list);
    }
    destroy_array(cases);
    return 0;
  }

  if ((*n_subregions) > 0) {
    (*subregions) = (struct matching_cases *)
                 (ascmalloc(((*n_subregions))*sizeof(struct matching_cases)));
    (*n_subregions) = 0;
    for(comb=0; comb<pos_cases;comb++) {
      if(cases[comb].diff_subregion) {
        (*subregions)[(*n_subregions)].case_list = cases[comb].case_list;
        cases[comb].case_list = NULL;
        (*subregions)[(*n_subregions)].ncases = cases[comb].ncases;
        cases[comb].ncases = 0;
        (*subregions)[(*n_subregions)].diff_subregion = 1;
        (*n_subregions)++;
      }
    }
  }

  for(comb=0; comb<pos_cases;comb++) {
    destroy_array(cases[comb].case_list);
  }
  destroy_array(cases);


  assign_cur_sub = 0;
  /*
   * Finding the subregion corresponding to the "original" configuration
   */
  for (d=0; d<numdvs; d++) {
    cur_dis = dv[d];
    dis_set_boolean_value(cur_dis,bval.cur_val[d]);
    dis_set_value(cur_dis,bval.cur_val[d]);
    dis_set_previous_value(cur_dis,bval.pre_val[d]);
  }
  cur_cases = cases_matching(disvars,&cur_ncases);
  caselist = cur_cases;
  if (cur_ncases > 1) {
    newcaselist = create_array(cur_ncases,int32);
    order_case(caselist,newcaselist,cur_ncases);
    cur_cases = newcaselist;
    destroy_array(caselist);
  } else {
    if (cur_ncases == 1) {
      newcaselist = create_array(1,int32);
      newcaselist[0] = caselist[1];
      cur_cases = newcaselist;
      destroy_array(caselist);
    }
  }
  for(comb=0; comb<(*n_subregions);comb++) {
    if ((*subregions)[comb].ncases == cur_ncases) {
      if(compare_case((*subregions)[comb].case_list,cur_cases,cur_ncases)) {
        (*cur_subregion) = comb;
        assign_cur_sub = 1;
        break;
      }
    }
  }

  if (!assign_cur_sub) {
    FPRINTF(ASCERR,"PANIC: original configuration not found\n");
  }

  destroy_array(cur_cases);
  destroy_array(dvarmodified);
  destroy_array(bval.cur_val);
  destroy_array(bval.pre_val);
  return 1;
}


/*
 * If some boundary(ies) has been crossed in the iterative scheme,
 * this function finds the boundary crossed (the first one, if many).
 * It returns the factor (less than 1) by which the step length has
 * to be multiplied son that the new point will lie precisely
 * at that boundary. This factor is found by using the method of
 * bisection
 */
static real64 return_to_first_boundary(slv_system_t server,
                       SlvClientToken asys,
                       struct real_values *rvalues,
                       var_filter_t *vfilter)
{
  slv9_system_t sys;
  struct bnd_boundary **bp, *cur_bnd;
  struct var_variable **incidences, **bnd_incidences;
  struct var_variable *cur_var;
  bnd_filter_t bfilter;
  struct boolean_values bval;
  real64 factor,fup,flo,newvalue;
  int32 *bndcrossed;
  int32 *inc_vars;
  int32 count,n_incidences,inc,conv_flag,still_crossed;
  int32 numbnds,numbndf,b,ind;
  int32 iter,n_iterations;
  FILE *lif;

  sys = SLV9(asys);
  check_system(sys);
  lif = LIF(sys);

  if( sys->blist == NULL ) {
    FPRINTF(ASCERR,"ERROR:  (slv9) return_to_first_boundary\n");
    FPRINTF(ASCERR,"         Boundary list was never set.\n");
    return 1.0;
  }

  if (!some_boundaries_crossed(server,asys)) {
    return 1.0;
  }

  bp = sys->blist;
  numbnds = slv_get_num_solvers_bnds(server);
  bfilter.matchbits = (BND_CROSSED);
  bfilter.matchvalue = (BND_CROSSED);
  numbndf = slv_count_solvers_bnds(server,&bfilter);
  bndcrossed = create_array(numbndf,int32);
  bval.cur_val = create_array(numbndf,int32);
  bval.pre_val = create_array(numbndf,int32);
  ind = 0;
  for (b=0; b<numbnds; b++) {
    cur_bnd = bp[b];
    if (bnd_crossed(cur_bnd)) {
      bndcrossed[ind] = b;
      bval.cur_val[ind] = bnd_status_cur(cur_bnd);
      bval.pre_val[ind] = bnd_status_pre(cur_bnd);
      ind++;
    }
  }

  count = 0;
  for (b=0; b<numbndf; b++) {
    cur_bnd = bp[bndcrossed[b]];
    n_incidences = bnd_n_real_incidences(cur_bnd);
    count = count + n_incidences;
  }

  incidences = (struct var_variable **)
               ( ascmalloc((count)*sizeof(struct var_variable *)));
  inc_vars = create_array(count,int32);
  count = 0;
  for (b=0; b<numbndf; b++) {
    cur_bnd = bp[bndcrossed[b]];
    bnd_incidences = bnd_real_incidence(cur_bnd);
    n_incidences = bnd_n_real_incidences(cur_bnd);
#if SHOW_BOUNDARY_ANALYSIS_DETAILS
    FPRINTF(lif,"boundary crossed = %d\n",bndcrossed[b]);
    FPRINTF(lif,"previous boundary status = %d\n",bval.pre_val[b]);
    FPRINTF(lif,"current boundary status = %d\n",bval.cur_val[b]);
#endif /* SHOW_BOUNDARY_ANALYSIS_DETAILS */
    for (inc=0; inc<n_incidences; inc++) {
      incidences[count] = bnd_incidences[inc];
      inc_vars[count] = var_mindex(incidences[count]);
      count++;
    }
  }

  /* bisection to find first boundary crossed */
  fup = 1.0;
  flo = 0.0;
  conv_flag = 0;
  iter = 0;

/*
 * Maximum number of bisection iterations. This must be modified
 * so that it becomes a parameter to be defined by the user
 */
  n_iterations = ITER_BIS_LIMIT;

#if SHOW_BOUNDARY_ANALYSIS_DETAILS
    for (inc=0; inc<count; inc++) {
      cur_var = incidences[inc];
      if(var_apply_filter(cur_var,vfilter)) {
        FPRINTF(lif,"Variable ");
        print_var_name(lif,sys,cur_var); PUTC('\n',lif);
        FPRINTF(lif,
                "previous value = %f\n",rvalues->pre_values[inc_vars[inc]]);
        FPRINTF(lif,"current value = %f\n",rvalues->cur_values[inc_vars[inc]]);
      }
    }
#endif /* SHOW_BOUNDARY_ANALYSIS_DETAILS */

  while (conv_flag == 0) {
    iter++;
    if (iter>n_iterations) {
      FPRINTF(ASCERR,"ERROR:  (slv9) return_to_first_boundary\n");
      FPRINTF(ASCERR,"Could not find the first boundary crossed \n");
      FPRINTF(ASCERR,"Returning the last factor calculated\n");
      break;
    }
    still_crossed = 0;
    factor = ( fup + flo ) / 2.0;
#if SHOW_BISECTION_DETAILS
    FPRINTF(lif,"fup = %f\n",fup);
    FPRINTF(lif,"flo = %f\n",flo);
    FPRINTF(lif,"factor = %f\n",factor);
#endif /* SHOW_BISECTION_DETAILS */
    for (inc=0; inc<count; inc++) {
      cur_var = incidences[inc];
      if(var_apply_filter(cur_var,vfilter)) {
        newvalue  = rvalues->pre_values[inc_vars[inc]] + factor *
                    ( rvalues->cur_values[inc_vars[inc]] -
                    rvalues->pre_values[inc_vars[inc]] );
        var_set_value(cur_var,newvalue);
#if SHOW_BISECTION_DETAILS
        FPRINTF(lif,"Variable ");
        print_var_name(lif,sys,cur_var); PUTC('\n',lif);
        FPRINTF(lif,"value after factor = %f\n",newvalue);
#endif /* SHOW_BISECTION_DETAILS */
      }
    }

    update_boundaries(server,asys);
    for (b=0; b<numbndf; b++) {
      cur_bnd = bp[bndcrossed[b]];
#if SHOW_BISECTION_DETAILS
      FPRINTF(lif,"previous status = %d\n", bval.pre_val[b]);
      FPRINTF(lif,"status aftert factor = %d\n",bnd_status_cur(cur_bnd));
#endif /* SHOW_BISECTION_DETAILS */
      if ( bnd_status_cur(cur_bnd) != bval.pre_val[b] ) {
        still_crossed = 1;
      }
    }
#if SHOW_BISECTION_DETAILS
      FPRINTF(lif,"still_crossed = %d\n",still_crossed);
#endif /* SHOW_BISECTION_DETAILS */
    if (still_crossed) {
      fup = factor;
    } else {
      flo = factor;
      for (b=0; b<numbndf; b++) {
        cur_bnd = bp[bndcrossed[b]];
        bnd_set_pre_status(cur_bnd,bval.pre_val[b]);
        bnd_set_cur_status(cur_bnd,bval.pre_val[b]);
        if (bnd_at_zero(cur_bnd)) {
#if SHOW_BOUNDARY_ANALYSIS_DETAILS
          FPRINTF(ASCERR,"boundary at zero = %d\n",bndcrossed[b]);
          FPRINTF(lif,"factor = %f\n",factor);
          for (inc=0; inc<count; inc++) {
            cur_var = incidences[inc];
            if(var_apply_filter(cur_var,vfilter)) {
            FPRINTF(lif,"Variable ");
            print_var_name(lif,sys,cur_var); PUTC('\n',lif);
            FPRINTF(lif,"value after factor = %f\n",var_value(cur_var));
            }
          }
#endif  /* SHOW_BOUNDARY_ANALYSIS_DETAILS */
          conv_flag = 1;
        }
      }
    }
  }
  destroy_array(bndcrossed);
  destroy_array(inc_vars);
  destroy_array(bval.cur_val);
  destroy_array(bval.pre_val);
  destroy_array(incidences);

  return factor;
}


/*
 *  Storing values of real variables.
 *  ---------------------------------
 *
 *  We use the master list of variables since its order does not change
 *  and it is given by the master index. We do not touch the master list,
 *  we only use its order.
 */

/*
 * Store the values of the var_variables before a newton-like iteration
 */
static void store_real_pre_values(slv_system_t server,
                  struct real_values *rvalues)
{
  struct var_variable **master;
  struct var_variable *var;
  int v, vlen;

  master = slv_get_master_var_list(server);
  vlen = slv_get_num_master_vars(server);

  rvalues->pre_values = create_array(vlen,real64);

  for (v=0; v<vlen; v++) {
    var = master[v];
    rvalues->pre_values[v] = var_value(var);
  }
}

/*
 * Store the values of the var_variables after a newton-like iteration
 */
static void store_real_cur_values(slv_system_t server,
                  struct real_values *rvalues)
{
  struct var_variable **master;
  struct var_variable *var;
  int v, vlen;

  master = slv_get_master_var_list(server);
  vlen = slv_get_num_master_vars(server);

  rvalues->cur_values = create_array(vlen,real64);

  for (v=0; v<vlen; v++) {
     var = master[v];
     rvalues->cur_values[v] = var_value(var);
  }
}

/*
 * After the length of the step has been modified so that the current point
 * lies at a boundary, the values of all the variables is updated so that
 * they all reduce the length of their step by the same factor.
 */
static void update_real_var_values(slv_system_t server,
                       struct real_values *rvalues,
                   var_filter_t *vfilter, real64 factor)
{
  struct var_variable **master;
  struct var_variable *var;
  real64 newvalue;
  int v, vlen;

  master = slv_get_master_var_list(server);
  vlen = slv_get_num_master_vars(server);

  for (v=0; v<vlen; v++) {
    var = master[v];
    if(var_apply_filter(var,vfilter)) {
      newvalue = rvalues->pre_values[v] +
                factor * (rvalues->cur_values[v] - rvalues->pre_values[v]);
      var_set_value(var,newvalue);
    }
  }
  destroy_array(rvalues->cur_values);
  destroy_array(rvalues->pre_values);
}


/*
 * Set the flagbit NONBASIC for all the variables in the list
 * to the value passed as argument
 */
static void set_nonbasic_status_in_var_list(slv_system_t server,
                            uint32 value)
{
  struct var_variable **master;
  struct var_variable *var;
  int v, vlen;

  master = slv_get_master_var_list(server);
  vlen = slv_get_num_master_vars(server);

  for (v=0; v<vlen; v++) {
    var = master[v];
    var_set_nonbasic(var,value);
  }
}


/*
 * After the length of the step has been modified so that the current point
 * lies at a boundary, the residuals of the equations are updated.
 */
static void update_relations_residuals(slv_system_t server)
{
  struct rel_relation **master;
  struct rel_relation *rel;
  rel_filter_t rfilter;
  real64 resid;
  int32 r, rlen, status;

  master = slv_get_master_rel_list(server);
  rlen = slv_get_num_master_rels(server);

  rfilter.matchbits = (REL_INCLUDED | REL_EQUALITY);
  rfilter.matchvalue = (REL_INCLUDED | REL_EQUALITY);

  Asc_SignalHandlerPush(SIGFPE,SIG_IGN);
  for (r=0; r<rlen; r++) {
    rel = master[r];
    if(rel_apply_filter(rel,&rfilter)) {
      resid = relman_eval(rel,&status,1);
    }
  }
  Asc_SignalHandlerPop(SIGFPE,SIG_IGN);
}


/*
 *  Optimization subroutines for CONOPT
 *  ---------------------------------
 */

/*
 * COIRMS Based on the information provided in Coispz, CONOPT will
 * allocate the number of vectors into which the user can define
 * the details of the model. The details of the model are defined
 * here.
 *
 * COIRMS(lower, curr, upper, vsta, type,rhs, fv, esta, colsta,
 * rowno, value, nlflag, n, m, n1, nz, usrmem)
 *
 * lower - lower bounds on the variables
 * curr  - intial values of the variables
 * upper - upper bounds on the variables
 * vsta  - initial status of the variable(o nonbasic, 1 basic)
 * type  - types of equations (0 equality,1 greater,2 less)
 * rhs   - values of the right hand sides
 * fv    - sum of the nonlinear terms in the initial point
 * esta  - initial status of the slack in the constraint (nonbasic,basic)
 * colsta- start of column pointers
 * rowno - row or equation numbers of the nonzeros
 * value - values of the jacobian elements
 * nlflag- nonlinearity flags(0 nonzero constant,1 varying)
 * n     - number of variables
 * m     - number of constraints
 * n1    - n+1
 * nz    - number of jacobian elements
 * usrmem- user memory defined by conopt
 */
static void slv9_coirms(real64 *lower, real64 *curr, real64 *upper,
            int32 *vsta,  int32 *type, real64 *rhs, real64 *fv,
            int32 *esta,  int32 *colsta, int32 *rowno,
            real64 *value, int32 *nlflag, int32 *n, int32 *m,
            int32 *n1, int32 *nz, real64 *usrmem)
{
  slv9_system_t sys;
  struct var_variable *var;
  struct var_variable **varlist;
  struct opt_matrix *coeff_matrix;
  static var_filter_t vfilter;
  real64 obj_val, deriv;
  real64 nominal, up, low, uplow;
  int32 num_var, n_subregions, c, num_eqns;
  int32 numnz, eq;
  int32 count, totvar;

  /*
   * stop gcc whining about unused parameters
   */
   (void)vsta;
   (void)esta;

  sys = (slv9_system_t)usrmem;
  n_subregions = sys->subregions;
  coeff_matrix = sys->coeff_matrix;
  num_var = (*n) - n_subregions;
  num_eqns = num_var + 1;

  vfilter.matchbits = (VAR_ACTIVE_AT_BND | VAR_INCIDENT
               | VAR_SVAR | VAR_FIXED);
  vfilter.matchvalue = (VAR_ACTIVE_AT_BND | VAR_INCIDENT | VAR_SVAR);
  varlist = sys->mvlist;
  totvar = sys->mvtot;

  /*
   * Variables: Current Value, lower value and upper value. Note that for
   * this problem the variables are the vector of steps dx. So we "invent"
   * approximations for the bounds based on the bounds of the real
   * variables of the problem. The use of the parameter INFINITY is
   * Hack to keep CONOPT from complaining for large bounds.
   */

  count = 0;
  for (c=0; c<totvar; c++) {
    var = varlist[c];
    if (var_apply_filter(var,&vfilter)) {
      nominal = var_nominal(var);
      low = var_lower_bound(var);
      up = var_upper_bound(var);
      uplow = fabs( up - low);
      lower[count] = -uplow > -INFINITY ? -uplow : -0.5*INFINITY;
      upper[count] = uplow < INFINITY ? uplow : 0.5*INFINITY;
      curr[count] = 0.5 * nominal;
      count++;
    }
  }
  /* alphas for each subregion */
  for (c=count; c<(*n); c++) {
      lower[c] = 0.0;
      upper[c] = 1.0;
      curr[c] =  1.0;
  }


  /*
   * vsta not in use since STATOK, ipsz[14], is zero
   */

  /*
   * All the equations, but the last row (which is the objective), are
   * equalities.
   */
  for (c = 0; c < (*m); c++) {
    type[c] = 0;
  }
  type[(*m)-1] = 3;


  /*
   * RHS. It is zero for all the equations except the summation of
   * alphas, whose RHS is one.
   */
  for (c = 0; c < (*m); c++) {
    rhs[c] = 0;
  }
  rhs[(*m)-2] = 1.0;

  /*
   * fv =0 for all linear relations. For the objective is the two
   * norm
   */
  for (c = 0; c < (*m); c++) {
    fv[c] = 0;
  }
  obj_val = 0.0;
  for (c = 0; c<num_var; c++) {
    obj_val = obj_val + (curr[c] * curr[c]);
  }
  fv[(*m)-1] = obj_val;

  /*
   * esta not used since STATOK is zero
   */


  /*
   * For the following parameters, it is important ot see that:
   * 1) The values for the rows and nonzeros that conopt wants start
   *    with 1, not with 0.
   * 2) The indeces of the arrays that we are using in the C side start
   *    with 0.
   */

  /*
   * colsta
   */

  for (c=0; c<num_var; c++) {
    colsta[c] = 1 + 2 * c;
  }

  for (c=num_var; c<(*n); c++) {
    colsta[c] = 2 * num_var + num_eqns * (c - num_var