// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
/*! \file algebra.c
 * \ingroup gm
 */

/** \addtogroup gm
 *
 * @{
 */

/****************************************************************************/
/*                                                                          */
/* File:      algebra.c                                                     */
/*                                                                          */
/* Purpose:   management for algebraic structures                           */
/*                                                                          */
/* Author:    Klaus Johannsen                                               */
/*            Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen   */
/*            Universitaet Heidelberg                                       */
/*            Im Neuenheimer Feld 294                                       */
/*            6900 Heidelberg                                               */
/*            email: ug@ica3.uni-stuttgart.de                               */
/*                                                                          */
/* blockvector data structure:                                              */
/*           Christian Wrobel                                               */
/*           Institut fuer Computeranwendungen III                          */
/*           Universitaet Stuttgart	                                        */
/*           Pfaffenwaldring 27                                             */
/*           70569 Stuttgart                                                */
/* email:    ug@ica3.uni-stuttgart.de                                       */
/*                                                                          */
/* History:  1.12.93 begin, ug 3d                                           */
/*           26.10.94 begin combination 2D/3D version                       */
/*           28.09.95 blockvector implemented (Christian Wrobel)            */
/*                                                                          */
/* Remarks:                                                                 */
/*                                                                          */
/****************************************************************************/


/****************************************************************************/
/*                                                                          */
/* defines to exclude functions                                             */
/*                                                                          */
/****************************************************************************/


/****************************************************************************/
/*                                                                          */
/* include files                                                            */
/* system include files                                                     */
/* application include files                                                */
/*                                                                          */
/****************************************************************************/

#include <config.h>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>

#include <dune/common/unused.hh>

#include <dune/uggrid/low/architecture.h>
#include <dune/uggrid/low/debug.h>
#include <dune/uggrid/low/fifo.h>
#include <dune/uggrid/low/general.h>
#include <dune/uggrid/low/heaps.h>
#include <dune/uggrid/low/misc.h>
#include <dune/uggrid/low/namespace.h>
#include <dune/uggrid/low/ugenv.h>
#include <dune/uggrid/low/ugtypes.h>

#include <dune/uggrid/ugdevices.h>

#include "algebra.h"
#include "cw.h"
#include "dlmgr.h"
#include "gm.h"
#include "elements.h"
#include "refine.h"
#include "ugm.h"
#include "evm.h"
#include "dlmgr.h"
#include "mgheapmgr.h"

#ifdef ModelP
#include <dune/uggrid/parallel/dddif/parallel.h>
#endif


USING_UG_NAMESPACE
USING_UGDIM_NAMESPACE
  using namespace PPIF;


/****************************************************************************/
/*                                                                          */
/* defines in the following order                                           */
/*                                                                          */
/*    compile time constants defining static data size (i.e. arrays)        */
/*    other constants                                                       */
/*    macros                                                                */
/*                                                                          */
/****************************************************************************/

/** \brief Resolution for LexAlgDep */
#define ORDERRES                1e-3

/** \brief For GetDomainPart indicating an element is meant rather than an element side */
#define NOSIDE          -1

/** \brief Constants for the direction of domain halfening */
#define BV_VERTICAL     0
#define BV_HORIZONTAL   1

/****************************************************************************/
/*                                                                          */
/* data structures used in this source file (exported data structures are   */
/* in the corresponding include file!)                                      */
/*                                                                          */
/****************************************************************************/

/****************************************************************************/
/*                                                                          */
/* definition of exported global variables                                  */
/*                                                                          */
/****************************************************************************/

const char* NS_DIM_PREFIX ObjTypeName[MAXVOBJECTS];

/****************************************************************************/
/*                                                                          */
/* definition of variables global to this source file only (static!)        */
/*                                                                          */
/****************************************************************************/

static INT theAlgDepDirID;                      /* env type for Alg Dep dir	*/
static INT theAlgDepVarID;                      /* env type for ALG_DEP vars	*/

static INT theFindCutDirID;                     /* env type for FindCut dir                     */
static INT theFindCutVarID;                     /* env type for FIND_CUT vars                   */

#ifdef __TWODIM__
static MULTIGRID *GBNV_mg;                      /* multigrid							*/
static INT GBNV_MarkKey;                        /* key for Mark/Release					*/
#endif
static INT GBNV_n;                                      /* list items							*/
static INT GBNV_curr;                           /* curr pos								*/
static VECTOR **GBNV_list=NULL;         /* list pointer							*/

/****************************************************************************/
/*                                                                          */
/* definition of variables global to this source file only (static!)        */
/*                                                                          */
/****************************************************************************/

/* for LexOrderVectorsInGrid */
static DOUBLE InvMeshSize;

REP_ERR_FILE

/****************************************************************************/
/** \brief Compute part information of geometrical object
 *
 * @param  s2p - table translating subdomain to domain part
 * @param  obj - geometric object (node, element or edge)
 * @param  side - if element side is meant for obj==element side has to be >=0, negative else

   Compute the part info for a geometrical object including element sides.

 * @return <ul>
 *   <li>   part if ok </li>
 *   <li>   -n else </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetDomainPart (const INT s2p[], const GEOM_OBJECT *obj, INT side)
{
  NODE *nd,*n0,*n1;
  EDGE *ed;
  ELEMENT *elem;
  VERTEX *v0,*v1;
  BNDS *bs;
  INT part=-1,subdom,move,left,right;

  switch (OBJT(obj))
  {
  case NDOBJ :
    nd = (NODE*)obj;
    v0 = MYVERTEX(nd);
    if (OBJT(v0)==IVOBJ) {
      subdom = NSUBDOM(nd);
      ASSERT(subdom>0);
      part = s2p[subdom];
    }
    else
    {
      /* get part info from domain module */
      if (BNDP_BndPDesc(V_BNDP(v0),&move,&part))
        REP_ERR_RETURN(-2);
      ASSERT(NSUBDOM(nd) == 0);
    }
    break;

  case IEOBJ :
  case BEOBJ :
    elem = (ELEMENT*)obj;
    if (side==NOSIDE)
    {
      /* get info for element */

      subdom = SUBDOMAIN(elem);
      ASSERT(subdom>0);
      part = s2p[subdom];
    }
    else
    {
      /* get info for element side */

      ASSERT(side<SIDES_OF_ELEM(elem));
      ASSERT(side>=0);

      if ((OBJT(elem)==BEOBJ) && ((bs = ELEM_BNDS(elem,side))!=NULL))
      {
        /* this is a boundary side: ask domain module */
        if (BNDS_BndSDesc(ELEM_BNDS(elem,side),&left,&right,&part))
          REP_ERR_RETURN(-3);
      }
      else
      {
        /* there still is the possibility that the side is a boundary side
           because VECTORs are created while CreateElement but boundary sides later
           by CreateSonElementSide.
           The vector eventually will be reallocated by ReinspectSonSideVector later */
        subdom = SUBDOMAIN(elem);
        ASSERT(subdom>0);
        part = s2p[subdom];
      }
    }
    break;

  case EDOBJ :
    ed = (EDGE*)obj;
    n0 = NBNODE(LINK0(ed));
    n1 = NBNODE(LINK1(ed));
    v0 = MYVERTEX(n0);
    v1 = MYVERTEX(n1);
    if ((OBJT(v0)==BVOBJ) && (OBJT(v1)==BVOBJ))
      if (BNDP_BndEDesc(V_BNDP(v0),V_BNDP(v1),&part) == 0)
        return(part);
    subdom = EDSUBDOM(ed);
    if (subdom > 0)
      return(s2p[subdom]);
    subdom = NSUBDOM(n0);
    if (subdom > 0)
      return(s2p[subdom]);
    subdom = NSUBDOM(n1);
    if (subdom > 0)
      return(s2p[subdom]);
    REP_ERR_RETURN(-4);

  default : REP_ERR_RETURN (-5);
  }
  return (part);
}

#ifdef ModelP
INT NS_DIM_PREFIX GetVectorSize (GRID *theGrid, INT VectorObjType, GEOM_OBJECT *object)
{
  MULTIGRID *mg;
  INT part,vtype;

  mg = MYMG(theGrid);
  part = GetDomainPart(BVPD_S2P_PTR(MG_BVPD(mg)),object,NOSIDE);
  if (part < 0)
    REP_ERR_RETURN(-1);
  vtype = FMT_PO2T(MGFORMAT(mg),part,VectorObjType);

  return(FMT_S_VEC_TP(MGFORMAT(mg),vtype));
}
#endif

/****************************************************************************/
/** \brief  Return pointer to a new vector structure
 *
 * @param  theGrid - grid where vector should be inserted
 * @param  DomPart - part of the domain where vector is created
 * @param  ObjType - one of the types defined in gm
 * @param  object  - associate vector with this object
 * @param  vHandle - handle of new vector, i.e. a pointer to a pointer where
                                a pointer to the new vector is placed.

   This function returns a pointer to a new vector structure.
   The vector type is determined by DomPart and ObjType
   First the free list is checked for a free entry, if none
   is available, a new structure is allocated from the heap.

 * @return <ul>
 *   <li>     0 if ok  </li>
 *   <li>     1 if error occured.	 </li>
   </ul>
 */
/****************************************************************************/

static INT CreateVectorInPart (GRID *theGrid, INT DomPart, INT VectorObjType,
                               GEOM_OBJECT *object, VECTOR **vHandle)
{
  MULTIGRID *theMG;
  VECTOR *pv;
  INT ds, Size, vtype;

  *vHandle = NULL;

  theMG = MYMG(theGrid);
  vtype = FMT_PO2T(MGFORMAT(theMG),DomPart,VectorObjType);
  ds = FMT_S_VEC_TP(MGFORMAT(theMG),vtype);
  if (ds == 0)
    return (0);                         /* HRR: this is ok now, no XXXXVEC in part of the domain */

  Size = sizeof(VECTOR)-sizeof(DOUBLE)+ds;
  pv = (VECTOR *)GetMemoryForObject(theMG,Size,VEOBJ);
  if (pv==NULL)
    REP_ERR_RETURN(1);

  /* initialize data */
  SETOBJT(pv,VEOBJ);
  SETVTYPE(pv,vtype);
  SETVPART(pv,DomPart);
  ds = VPART(pv);
  if (ds!=DomPart)
    return (1);
  SETVDATATYPE(pv,BITWISE_TYPE(vtype));
  SETVOTYPE(pv,VectorObjType);
  SETVCLASS(pv,3);
  SETVNCLASS(pv,0);
  SETVBUILDCON(pv,1);
  SETVNEW(pv,1);
  /* SETPRIO(dddContext, pv,PrioMaster); */

#ifndef ModelP
  // Dune uses the id field for face indices in sequential grids
  pv->id = (theGrid->mg->vectorIdCounter)++;
#endif

        #ifdef ModelP
  DDD_AttrSet(PARHDR(pv),GRID_ATTR(theGrid));
        #endif

  VOBJECT(pv) = object;
  VINDEX(pv) = (long)NVEC(theGrid);
  SUCCVC(pv) = FIRSTVECTOR(theGrid);
  VSTART(pv) = NULL;

  GRID_LINK_VECTOR(theGrid,pv,PrioMaster);

  *vHandle = pv;

  PRINTDEBUG(gm,1,("%s-vector created (%d): p=%d, t=%d\n",ObjTypeName[VOTYPE(pv)],ID(VOBJECT(pv)),VPART(pv),VTYPE(pv)));

  return (0);
}

/****************************************************************************/
/** \brief Return pointer to a new vector structure
 *
 * @param  theGrid - grid where vector should be inserted
 * @param  VectorObjType - one of the types defined in gm
 * @param  object  - associate vector with this object
 * @param  vHandle - handle of new vector, i.e. a pointer to a pointer where
                                a pointer to the new vector is placed.

   This function returns a pointer to a new vector structure. First the free list
   is checked for a free entry, if none is available, a new structure is allocated
   from the heap.

 * @return <ul>
 *   <li>     0 if ok  </li>
 *   <li>     1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX CreateVector (GRID *theGrid, INT VectorObjType, GEOM_OBJECT *object, VECTOR **vHandle)
{
  MULTIGRID *mg;
  INT part;

  *vHandle = NULL;
  mg = MYMG(theGrid);

  part = GetDomainPart(BVPD_S2P_PTR(MG_BVPD(mg)),object,NOSIDE);

  if (part < 0)
    REP_ERR_RETURN(1);
  if (CreateVectorInPart(theGrid,part,VectorObjType,object,vHandle)) {
    REP_ERR_RETURN(1);
  }
  else
    return (0);
}

INT NS_DIM_PREFIX CreateSideVector (GRID *theGrid, INT side, GEOM_OBJECT *object, VECTOR **vHandle)
{
  MULTIGRID *mg;
  INT part;

  *vHandle = NULL;
  mg = MYMG(theGrid);
  part = GetDomainPart(BVPD_S2P_PTR(MG_BVPD(mg)),object,side);
  if (part<0)
    REP_ERR_RETURN(1);

  if (CreateVectorInPart(theGrid,part,SIDEVEC,object,vHandle))
    REP_ERR_RETURN(1);

  SETVECTORSIDE(*vHandle,side);
  SETVCOUNT(*vHandle,1);

  return (0);
}

/****************************************************************************/
/** \brief Return pointer to a new connection structure
 *
 * @param  theGrid - grid where matrix should be inserted
 * @param  from - source vector
 * @param  to - destination vector

   This function allocates a new CONNECTION and inserts the two
   MATRIX structures in the lists of from and to vector.
   Since the operation is symmetric, the order of from and to
   is not important.

 * @return <ul>
 *   <li>   NULL if error occured. </li>
 *   <li>   else a pointer to the new CONNECTION is returned. </li>
 * </ul>
 */
/****************************************************************************/

CONNECTION * NS_DIM_PREFIX CreateConnection (GRID *theGrid, VECTOR *from, VECTOR *to)
{
  MULTIGRID *theMG;
  CONNECTION *pc;
  MATRIX *pm;
  INT RootType, DestType, MType, ds, Diag, Size;

  /* set Diag, RootType and DestType	*/
  Diag = ((from == to) ? 1 : 0);
  RootType = VTYPE(from);
  DestType = VTYPE(to);
  if (Diag)
    MType=DIAGMATRIXTYPE(RootType);
  else
    MType=MATRIXTYPE(RootType,DestType);

  /* check expected size */
  theMG = MYMG(theGrid);
  ds = FMT_S_MAT_TP(MGFORMAT(theMG),MType);
  if (ds == 0)
    return (NULL);
  Size = sizeof(MATRIX)-sizeof(DOUBLE)+ds;
  if (MSIZEMAX<Size) return (NULL);

  /* is there already the desired connection ? */
  pc = GetConnection(from,to);
  if (pc != NULL)
  {
    SETCEXTRA(pc,0);
    return (pc);
  }

  if (Diag)
    pc = (CONNECTION*)GetMemoryForObject(theMG,Size,MAOBJ);
  else
    pc = (CONNECTION*)GetMemoryForObject(theMG,2*Size,COOBJ);
  if (pc==NULL) return (NULL);

  /* initialize data */
  pm = CMATRIX0(pc);
  SETOBJT(pm,MAOBJ);
  SETMROOTTYPE(pm,RootType);
  SETMDESTTYPE(pm,DestType);
  SETMDIAG(pm,Diag);
  SETMOFFSET(pm,0);
  SETMSIZE(pm,Size);
  SETMNEW(pm,1);
  SETCEXTRA(pc,0);
  MDEST(pm) = to;
  if (!Diag)
  {
    pm = CMATRIX1(pc);
    CTRL(pm) = 0;
    SETOBJT(pm,MAOBJ);
    SETMROOTTYPE(pm,DestType);
    SETMDESTTYPE(pm,RootType);
    SETMDIAG(pm,Diag);
    SETMOFFSET(pm,1);
    SETMSIZE(pm,Size);
    SETMNEW(pm,1);
    MDEST(pm) = from;
  }

  /* set sizes */
  if (!Diag)
  {
    Size = (char*)pm - (char*)pc;
    SETMSIZE(pc,Size);
    SETMSIZE(pm,Size);
  }

  /* put in matrix list */
  if (Diag)
  {
    /* insert at first place in the list (only one matrix) */
    MNEXT(CMATRIX0(pc)) = VSTART(from);
    VSTART(from) = CMATRIX0(pc);
  }
  else
  {
    /* insert at second place in the list (both matrices) */
    pm = VSTART(from);
    if (pm == NULL)
    {
      MNEXT(CMATRIX0(pc)) = NULL;
      VSTART(from) = CMATRIX0(pc);
    }
    else
    {
      MNEXT(CMATRIX0(pc)) = MNEXT(pm);
      MNEXT(pm) = CMATRIX0(pc);
    }

    pm = VSTART(to);
    if (pm == NULL)
    {
      MNEXT(CMATRIX1(pc)) = NULL;
      VSTART(to) = CMATRIX1(pc);
    }
    else
    {
      MNEXT(CMATRIX1(pc)) = MNEXT(pm);
      MNEXT(pm) = CMATRIX1(pc);
    }
  }

  /* counters */
  theGrid->nCon++;

  return(pc);
}

/****************************************************************************/
/** \brief Return pointer to a new matrix structure with extra flag set.
 *
 * @param  theGrid - grid level where connection will be inserted.
 * @param  from,to - Pointers to vectors where connection is inserted.

   This function returns a pointer to a new CONNECTION
   structure with extra flag set. This e.g. for a direct solver
   or ILU with fill in. The new connections can be distinguished
   from the connections necessary for the stiffness matrix.

 * @return <ul>
 *   <li>   NULL if error occured. </li>
 *   <li>   else pointer to new CONNECTION </li>
   </ul>
 */
/****************************************************************************/

CONNECTION      *NS_DIM_PREFIX CreateExtraConnection    (GRID *theGrid, VECTOR *from, VECTOR *to)
{
  CONNECTION *pc;

  pc = CreateConnection(theGrid,from,to);
  if (pc==NULL) return(NULL);
  SETCEXTRA(pc,1);
  return(pc);
}

INT NS_DIM_PREFIX CreateElementList (GRID *theGrid, NODE *theNode, ELEMENT *theElement)
{
  ELEMENTLIST *pel;

  for (pel=NODE_ELEMENT_LIST(theNode); pel!=NULL; pel=NEXT(pel))
    if(pel->el==theElement)
      return(0);

  pel = (ELEMENTLIST *)GetMemoryForObject(theGrid->mg,
                                          sizeof(ELEMENTLIST),MAOBJ);
  if (pel == NULL)
    return(1);

  pel->next = NODE_ELEMENT_LIST(theNode);
  pel->el = theElement;
  NDATA(theNode) = (void *) pel;

  return(0);
}

/****************************************************************************/
/** \brief Remove vector from the data structure
 *
 * @param  theGrid - grid level where theVector is in.
 * @param  theVector - VECTOR to be disposed.

   This function removes vector from the data structure and places
   it in the free list.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX DisposeVector (GRID *theGrid, VECTOR *theVector)
{
  MATRIX *theMatrix, *next;
  INT Size;

#ifdef __PERIODIC_BOUNDARY__
  SETPVCOUNT(theVector,PVCOUNT(theVector)-1);
  if (((INT)PVCOUNT(theVector)) > 0)
  {
    PRINTDEBUG(gm,1,("DisposeVector: v=" VINDEX_FMTX
                     " NOT disposed count=%d\n",
                     VINDEX_PRTX(theVector),PVCOUNT(theVector)));
    return (0);
  }
  PRINTDEBUG(gm,1,("DisposeVector: v=" VINDEX_FMTX
                   " disposed count=%d\n",
                   VINDEX_PRTX(theVector),PVCOUNT(theVector)));
#endif

  if (theVector == NULL)
    return(0);

  HEAPFAULT(theVector);

  /* remove all connections concerning the vector */
  for (theMatrix=VSTART(theVector); theMatrix!=NULL; theMatrix=next)
  {
    next = MNEXT(theMatrix);
    if (DisposeConnection(theGrid,MMYCON(theMatrix)))
      RETURN (1);
  }

  /* now remove vector from vector list */
  GRID_UNLINK_VECTOR(theGrid,theVector);

  /* reset count flags */
  SETVCOUNT(theVector,0);


  /* delete the vector itself */
  Size = sizeof(VECTOR)-sizeof(DOUBLE)
         + FMT_S_VEC_TP(MGFORMAT(MYMG(theGrid)),VTYPE(theVector));
  if (PutFreeObject(theGrid->mg,theVector,Size,VEOBJ))
    RETURN(1);

  return(0);
}

/****************************************************************************/
/* \brief Change vector allocated with wrong part

 * @param  g - grid level where the element is in.
 * @param  elem - element of side vector
 * @param  side - element side
 * @param  vHandle - handle to side vector (inialized with old, may be changed)

   This changes a side vector which was allocated with the wrong part (maybe unknown for side vectors
   when creating an element).

 * @return <ul>
 *   <li>   GM_OK if ok
 *   <li>   GM_ERROR if error occured.
 */
/****************************************************************************/

INT NS_DIM_PREFIX ReinspectSonSideVector (GRID *g, ELEMENT *elem, INT side, VECTOR **vHandle)
{
  MULTIGRID *mg;
  VECTOR *vold,*vnew;
  FORMAT *fmt;
  INT partnew,partold,vtnew,vtold,dsnew,dsold;

  mg  = MYMG(g);
  fmt = MGFORMAT(mg);

  vold = *vHandle;

  /* check whether part has actually changed */
  partold = (vold!=NULL) ? VPART(vold) : BVPD_S2P(MG_BVPD(mg),SUBDOMAIN(elem));
  partnew = GetDomainPart(BVPD_S2P_PTR(MG_BVPD(mg)),(GEOM_OBJECT*)elem,side);
  if (partnew<0)
    REP_ERR_RETURN(GM_ERROR);
  if (partnew==partold)
    return (GM_OK);

  /* check whether vtype has actually changed */
  vtold = (vold!=NULL) ? VTYPE(vold) : FMT_PO2T(fmt,partold,SIDEVEC);
  vtnew = FMT_PO2T(fmt,partnew,SIDEVEC);
  if (vtnew==vtold)
  {
    if (vold!=NULL)
    {
      /* just change part */
      SETVPART(vold,partnew);
    }
    PRINTDEBUG(gm,1,("SIDEVEC (%d,%d): part\n",ID(elem),side));
    return (GM_OK);
  }

  /* check whether size has actually changed */
  dsold = FMT_S_VEC_TP(fmt,vtold);
  dsnew = FMT_S_VEC_TP(fmt,vtnew);
  if (dsold==dsnew)
  {
    if (vold!=NULL)
    {
      /* just change part and type */
      SETVTYPE(vold,vtnew);
      SETVPART(vold,partnew);

      DisposeConnectionFromVector(g,vold);

      SETVBUILDCON(vold,1);
    }
    PRINTDEBUG(gm,1,("SIDEVEC (%d,%d): part and type\n",ID(elem),side));
    return (GM_OK);
  }

  PRINTDEBUG(gm,1,("SIDEVEC (%d,%d): part, type and size\n",ID(elem),side));

  /* create new vector */
  if (CreateVectorInPart(g,partnew,SIDEVEC,(GEOM_OBJECT*)elem,&vnew))
    REP_ERR_RETURN(GM_ERROR);

  /* now we can dispose the old vector */
  if (DisposeVector(g,vold))
    REP_ERR_RETURN(GM_ERROR);

  *vHandle = vnew;

  return (GM_OK);
}

/****************************************************************************/
/** \brief Remove connection from the data structure
 *
 * @param  theGrid - the grid to remove from
 * @param  theConnection - connection to dispose

   This function removes a connection from the data structure. The connection
   is removed from the list of the two vectors and is placed in the
   free list.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX DisposeConnection (GRID *theGrid, CONNECTION *theConnection)
{
  VECTOR *from, *to;
  MATRIX *Matrix, *ReverseMatrix, *SearchMatrix;

  HEAPFAULT(theConnection);

  /* remove matrix(s) from their list(s) */
  Matrix = CMATRIX0(theConnection);
  to = MDEST(Matrix);
  if (MDIAG(Matrix))
  {
    from = to;
    VSTART(to) = MNEXT(Matrix);
  }
  else
  {
    ReverseMatrix = CMATRIX1(theConnection);
    from = MDEST(ReverseMatrix);
    if (VSTART(from) == Matrix)
      VSTART(from) = MNEXT(Matrix);
    else
      for (SearchMatrix=VSTART(from); SearchMatrix!=NULL; SearchMatrix=MNEXT(SearchMatrix))
        if (MNEXT(SearchMatrix) == Matrix)
          MNEXT(SearchMatrix) = MNEXT(Matrix);
    if (VSTART(to) == ReverseMatrix)
      VSTART(to) = MNEXT(ReverseMatrix);
    else
      for (SearchMatrix=VSTART(to); SearchMatrix!=NULL; SearchMatrix=MNEXT(SearchMatrix))
        if (MNEXT(SearchMatrix) == ReverseMatrix)
          MNEXT(SearchMatrix) = MNEXT(ReverseMatrix);
  }

  /* free connection object */
  if (MDIAG(Matrix))
    PutFreeObject(MYMG(theGrid),Matrix,UG_MSIZE(Matrix),MAOBJ);
  else
    PutFreeObject(MYMG(theGrid),Matrix,2*UG_MSIZE(Matrix),COOBJ);

  theGrid->nCon--;

  /* return ok */
  return(0);
}

/****************************************************************************/
/** \brief Dispose one of two vectors associated to a face
 *
 * @param  theGrid - pointer to grid
 * @param  Elem0,side0 - first element and side
 * @param  Elem1,side1 - second element and side

   After grid refinement it may happen that two side vector are associated to a face
   in the grid.  The elements on both sides of the face each have their own side
   vector.  This is an inconsistent state -- there should be only one vector per face.
   This routine deletes one of the two side vectors and makes the data structure
   consistent again.  This is easier than only creating one unique side vector
   to begin with.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured.	 </li>
   </ul>
 */
/****************************************************************************/

#ifdef __THREEDIM__
INT NS_DIM_PREFIX DisposeDoubledSideVector (GRID *theGrid, ELEMENT *Elem0, INT Side0, ELEMENT *Elem1, INT Side1)
{
  VECTOR *Vector0, *Vector1;

  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
  {
    assert(NBELEM(Elem0,Side0)==Elem1 && NBELEM(Elem1,Side1)==Elem0);
    Vector0 = SVECTOR(Elem0,Side0);
    Vector1 = SVECTOR(Elem1,Side1);
    if (Vector0 == Vector1)
      return (0);
    if ((Vector0==NULL) || (Vector1==NULL))
      /* this is the case at boundaries between different parts
         the part not using vectors in SIDEs will not need a pointer
         to the side vector */
      return (0);
    assert(VCOUNT(Vector0)==1 && VCOUNT(Vector1)==1);
    assert(VSTART(Vector0)==NULL || VSTART(Vector1)==NULL);
    if (VSTART(Vector0)==NULL)
    {
      SET_SVECTOR(Elem0,Side0,Vector1);
      SETVCOUNT(Vector1,2);
      if (DisposeVector (theGrid,Vector0))
        RETURN (1);
    }
    else
    {
      SET_SVECTOR(Elem1,Side1,Vector0);
      SETVCOUNT(Vector0,2);
      if (DisposeVector (theGrid,Vector1))
        RETURN (1);
    }
    return (0);

  }

  RETURN (1);
}
#endif

/****************************************************************************/
/** \brief Remove all connections associated with a vector
 *
 * @param  theGrid - grid level where vector belongs to
 * @param  theVector - vector where connections are disposed from

   This function removes all connections from a vector.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX DisposeConnectionFromVector (GRID *theGrid, VECTOR *theVector)
{
  while(VSTART(theVector) != NULL)
    if (DisposeConnection (theGrid,MMYCON(VSTART(theVector))))
      return (1);

  return (0);
}


/****************************************************************************/
/** \brief Removes all connections from all vectors associated with an element
 *
 * @param  theGrid - grid level where element is on
 * @param  theElement - element from which to dispose connections

   This function removes all connections from all vectors
   associated with an element.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX DisposeConnectionFromElement (GRID *theGrid, ELEMENT *theElement)
{
  INT i;
  VECTOR *vList[20];
  INT cnt;

  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,ELEMVEC))
  {
    GetVectorsOfElement(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
    {
      if (DisposeConnectionFromVector(theGrid,vList[i])) RETURN(GM_ERROR);
      SETVBUILDCON(vList[i],1);
    }
  }
    #ifdef __THREEDIM__
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
  {
    GetVectorsOfSides(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
    {
      if (DisposeConnectionFromVector(theGrid,vList[i])) RETURN(GM_ERROR);
      SETVBUILDCON(vList[i],1);
    }
  }
    #endif
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
  {
    GetVectorsOfEdges(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
    {
      if (DisposeConnectionFromVector(theGrid,vList[i])) RETURN(GM_ERROR);
      SETVBUILDCON(vList[i],1);
    }
  }
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,NODEVEC))
  {
    GetVectorsOfNodes(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
    {
      if (DisposeConnectionFromVector(theGrid,vList[i])) RETURN(GM_ERROR);
      SETVBUILDCON(vList[i],1);
    }
  }

  return(GM_OK);
}

/****************************************************************************/
/** \brief Remove matrices
 *
 * @param  theGrid - the grid to remove from
 * @param  theElement - that element
 * @param  Depth -  that many slices around the element

   This function removes connections concerning an element from the data structure
   and stores flags saying: "connection has to be rebuild",
   it does this in a neighborhood of the elem of depth Depth, where depth
   is the distance in the element-neighborship-graph (see also FORMAT).

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

static INT DisposeConnectionFromElementInNeighborhood (GRID *theGrid, ELEMENT *theElement, INT Depth)
{
  INT i;

  if (Depth < 0) RETURN (GM_ERROR);

  if (theElement==NULL) RETURN (GM_OK);

  /* create connection at that depth */
  if (DisposeConnectionFromElement(theGrid,theElement))
    RETURN (GM_ERROR);
  SETEBUILDCON(theElement,1);

  /* dispose connection in neighborhood */
  if (Depth > 0)
  {
    for (i=0; i<SIDES_OF_ELEM(theElement); i++)
      if (DisposeConnectionFromElementInNeighborhood(theGrid,NBELEM(theElement,i),Depth-1))
        RETURN (GM_ERROR);
  }

  RETURN (GM_OK);
}

INT NS_DIM_PREFIX DisposeConnectionsInNeighborhood (GRID *theGrid, ELEMENT *theElement)
{
  INT Depth;
  Depth = (INT)(floor(0.5*(double)FMT_CONN_DEPTH_MAX(MGFORMAT(MYMG(theGrid)))));
  return(DisposeConnectionFromElementInNeighborhood(theGrid,theElement,Depth));
}

INT NS_DIM_PREFIX DisposeConnectionsFromMultiGrid (MULTIGRID *theMG)
{
  INT i;

  for (i=0; i<=TOPLEVEL(theMG); i++)
  {
    GRID *theGrid = GRID_ON_LEVEL(theMG,i);
    ELEMENT *theElement;
    NODE *theNode;

    theGrid = GRID_ON_LEVEL(theMG,i);
    for (theElement=PFIRSTELEMENT(theGrid); theElement!=NULL;
         theElement=SUCCE(theElement))
      if (DisposeConnectionsInNeighborhood(theGrid,theElement))
        REP_ERR_RETURN(1);

    if (NELIST_DEF_IN_GRID(theGrid))
      for (theNode = PFIRSTNODE(theGrid); theNode != NULL;
           theNode = SUCCN(theNode))
        if (DisposeElementList(theGrid,theNode))
          REP_ERR_RETURN(1);
  }

  return(0);
}

INT NS_DIM_PREFIX DisposeElementFromElementList (GRID *theGrid, NODE *theNode,
                                                 ELEMENT *theElement)
{
  ELEMENTLIST *pel,*next;

  pel = NODE_ELEMENT_LIST(theNode);
  if (pel == NULL) return(0);
  if (pel->el == theElement) {
    NDATA(theNode) = (void *) pel->next;
    return(PutFreeObject(theGrid->mg,pel,sizeof(ELEMENTLIST),MAOBJ));
  }
  next = pel->next;
  while (next != NULL) {
    if (next->el == theElement) {
      pel->next = next->next;
      return(PutFreeObject(theGrid->mg,next,sizeof(ELEMENTLIST),MAOBJ));
    }
    pel = next;
    next = pel->next;
  }

  return(0);
}

INT NS_DIM_PREFIX DisposeElementList (GRID *theGrid, NODE *theNode)
{
  ELEMENTLIST *pel,*next;

  pel = NODE_ELEMENT_LIST(theNode);
  while (pel != NULL) {
    next = pel->next;
    if (PutFreeObject(theGrid->mg,pel,sizeof(ELEMENTLIST),MAOBJ))
      return(1);
    pel = next;
  }
  NDATA(theNode) = NULL;

  return(0);
}

/****************************************************************************/
/** \brief Return pointer to matrix if it exists

 * @param FromVector - starting vector of the Matrix
 * @param ToVector - destination vector of the Matrix

   This function returns pointer to matrix if it exists. The function
   runs through the single linked list, since the list is
   assumed to be small (sparse matrix!) the cost is assumed to be negligible.

 * @return <ul>
 *   <li>      pointer to Matrix, </li>
 *   <li>      NULL if Matrix does not exist. </li>
   </ul>
 */
/****************************************************************************/

MATRIX * NS_DIM_PREFIX GetMatrix (const VECTOR *FromVector, const VECTOR *ToVector)
{
  MATRIX *theMatrix;

  for (theMatrix=VSTART(FromVector); theMatrix!=NULL; theMatrix = MNEXT(theMatrix))
    if (MDEST(theMatrix)==ToVector)
      return (theMatrix);

  /* return not found */
  return (NULL);
}

/****************************************************************************/
/** \brief Return pointer to connection if it exists

 * @param FromVector - starting vector of the con
 * @param ToVector - destination vector of the con

   This function returns pointer to connection if it exists.

 * @return <ul>
 *   <li>      pointer to </li>
 *   <li>      NULL if connection does not exist.  </li>
   </ul>
 */
/****************************************************************************/

CONNECTION * NS_DIM_PREFIX GetConnection (const VECTOR *FromVector, const VECTOR *ToVector)
{
  MATRIX *Matrix;

  Matrix = GetMatrix(FromVector,ToVector);
  if (Matrix != NULL)
    return (MMYCON(Matrix));

  /* return not found */
  return (NULL);
}

/****************************************************************************/
/** \brief Get a pointer list to all element data

 * @param theElement - that element
 * @param cnt - how many vectors
 * @param vList - array to store vector list

   This function returns a pointer to the VECTOR associated with the
   element (if the element is allowed to have one). cnt will either
   be 0 or 1.

 * @return <ul>
 *   <li>    GM_OK if ok </li>
 *   <li>    GM_ERROR	if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetVectorsOfElement (const ELEMENT *theElement, INT *cnt, VECTOR **vList)
{
  *cnt = 0;
  if (EVECTOR(theElement) != NULL)
    vList[(*cnt)++] = EVECTOR(theElement);

  IFDEBUG(gm,0)
  if (*cnt)
  {
    assert(vList[0] != NULL);
    assert(VOTYPE(vList[0]) == ELEMVEC);
  }
  ENDDEBUG

  return(GM_OK);
}

/****************************************************************************/
/** \brief Get a pointer list to all side data

 * @param theElement - that element
 * @param cnt - how many vectors
 * @param vList - array to store vector list

   This function gets a pointer array to all VECTORs in sides of the given element.

 * @return <ul>
 *   <li>    GM_OK if ok </li>
 *   <li>    GM_ERROR	if error occured. </li>
   </ul>
 */
/****************************************************************************/

#ifdef __THREEDIM__
INT NS_DIM_PREFIX GetVectorsOfSides (const ELEMENT *theElement, INT *cnt, VECTOR **vList)
{
  INT i;

  *cnt = 0;

  for (i=0; i<SIDES_OF_ELEM(theElement); i++)
    if (SVECTOR(theElement,i) != NULL)
      vList[(*cnt)++] = SVECTOR(theElement,i);

  IFDEBUG(gm,0)
  for (i=0; i<(*cnt); i++)
  {
    assert(vList[i] != NULL);
    assert(VOTYPE(vList[i]) == SIDEVEC);
  }
  ENDDEBUG

  return(GM_OK);
}
#endif

/****************************************************************************/
/** \brief Get a pointer list to all edge data

 * @param theElement -  that element
 * @param cnt - how many vectors
 * @param vList - array to store vector list

   This function gets a pointer array to all VECTORs in edges of the element.

 * @return <ul>
 *   <li>    GM_OK if ok </li>
 *   <li>    GM_ERROR	if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetVectorsOfEdges (const ELEMENT *theElement, INT *cnt, VECTOR **vList)
{
  EDGE *theEdge;
  INT i;

  *cnt = 0;
  for (i=0; i<EDGES_OF_ELEM(theElement); i++)
    if ((theEdge =
           GetEdge(CORNER(theElement,CORNER_OF_EDGE(theElement,i,0)),
                   CORNER(theElement,CORNER_OF_EDGE(theElement,i,1)))) != NULL)
      if (EDVECTOR(theEdge) != NULL)
        vList[(*cnt)++] = EDVECTOR(theEdge);

  IFDEBUG(gm,0)
  for (i=0; i<(*cnt); i++)
  {
    assert(vList[i] != NULL);
    assert(VOTYPE(vList[i]) == EDGEVEC);
  }
  ENDDEBUG

  return(GM_OK);
}

/****************************************************************************/
/** \brief Get a pointer list to all node data

 * @param theElement -  that element
 * @param cnt - how many vectors
 * @param vList - array to store vector list

   This function gets a pointer array to all VECTORs in nodes of the element.

 * @return <ul>
 *   <li>    GM_OK if ok </li>
 *   <li>    GM_ERROR	if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetVectorsOfNodes (const ELEMENT *theElement, INT *cnt, VECTOR **vList)
{
  INT i;

  *cnt = 0;
  for (i=0; i<CORNERS_OF_ELEM(theElement); i++)
    if (NVECTOR(CORNER(theElement,i)) != NULL)
      vList[(*cnt)++] = NVECTOR(CORNER(theElement,i));

  IFDEBUG(gm,0)
  for (i=0; i<(*cnt); i++)
  {
    assert(vList[i] != NULL);
    assert(VOTYPE(vList[i]) == NODEVEC);
  }
  ENDDEBUG

  return (GM_OK);
}

/****************************************************************************/
/** \brief Get a pointer list to all vector data of specified object type

 * @param theElement -  that element
 * @param type - fill array with vectors of this type
 * @param cnt - how many vectors
 * @param vList - array to store vector list

   This function returns a pointer array to all VECTORs of the element of the specified type.

 * @return <ul>
 *   <li>    GM_OK if ok </li>
 *   <li>    GM_ERROR	if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetVectorsOfOType (const ELEMENT *theElement, INT type, INT *cnt, VECTOR **vList)
{
  switch (type)
  {
  case NODEVEC :
    return (GetVectorsOfNodes(theElement,cnt,vList));
  case ELEMVEC :
    return (GetVectorsOfElement(theElement,cnt,vList));
  case EDGEVEC :
    return (GetVectorsOfEdges(theElement,cnt,vList));
        #ifdef __THREEDIM__
  case SIDEVEC :
    return (GetVectorsOfSides(theElement,cnt,vList));
        #endif
  }
  RETURN (GM_ERROR);
}

/****************************************************************************/
/** \brief Remove vectors with non-matching type from list

 * @param dt - data type including all vtypes needed
 * @param vec - vector list
 * @param cnt  - number of vectors return in the list

   This function removes vectors with non-matching types from the list.

 * @return
 *   Number of remaining vectors in the list
 */
/****************************************************************************/

INT NS_DIM_PREFIX DataTypeFilterVList (INT dt, VECTOR **vec, INT *cnt)
{
  INT i,n;

  n = *cnt;
  *cnt = 0;
  for (i=0; i<n; i++)
    if (VDATATYPE(vec[i]) & dt)
      vec[(*cnt)++] = vec[i];

  return (*cnt);
}

/****************************************************************************/
/** \brief Get vector list including all vectors of specified vtypes

 * @param theElement - pointer to an element
 * @param dt  - data type including all vtypes needed
 * @param obj - flags for objects types needed
 * @param cnt - number of vectors return in the list
 * @param vec - vector list

   This function gets a list of vectors of the specified vtypes corresponding to an element.

 * @return <ul>
 *   <li>   GM_OK if ok </li>
 *   <li>   GM_ERROR if error occured </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetVectorsOfDataTypesInObjects (const ELEMENT *theElement, INT dt, INT obj, INT *cnt, VECTOR *VecList[])
{
  INT i,n;

  *cnt = n = 0;

  if (obj & BITWISE_TYPE(NODEVEC))
  {
    if (GetVectorsOfNodes(theElement,&i,VecList) != GM_OK)
      return(GM_ERROR);
    n += i;
  }

  if (obj & BITWISE_TYPE(EDGEVEC))
  {
    if (GetVectorsOfEdges(theElement,&i,VecList+n) != GM_OK)
      return(GM_ERROR);
    n += i;
  }

  if (obj & BITWISE_TYPE(ELEMVEC))
  {
    if (GetVectorsOfElement(theElement,&i,VecList+n) != GM_OK)
      return(GM_ERROR);
    n += i;
  }

    #ifdef __THREEDIM__
  if (obj & BITWISE_TYPE(SIDEVEC))
  {
    if (GetVectorsOfSides(theElement,&i,VecList+n) != GM_OK)
      return(GM_ERROR);
    n += i;
  }
    #endif

  *cnt = n;

  /* remove vectors of types not needed */
  DataTypeFilterVList(dt,VecList,cnt);

  return (GM_OK);
}



static void PrintVectorTriple (int i)
{
  VECTOR *vec0 = GBNV_list[i];
  VECTOR *vec1 = GBNV_list[i+1];
  VECTOR *vec2 = GBNV_list[i+2];
  DUNE_UNUSED VERTEX *vtx0 = MYVERTEX((NODE*)VOBJECT(vec0));
  DUNE_UNUSED VERTEX *vtx1 = MYVERTEX((NODE*)VOBJECT(vec1));
  DUNE_UNUSED VERTEX *vtx2 = MYVERTEX((NODE*)VOBJECT(vec2));
  PrintDebug("0: VTYPE=%d XC=%.5g YC=%.5g\n",VTYPE(vec0),XC(vtx0),YC(vtx0));
  PrintDebug("1: VTYPE=%d XC=%.5g YC=%.5g\n",VTYPE(vec1),XC(vtx1),YC(vtx1));
  PrintDebug("2: VTYPE=%d XC=%.5g YC=%.5g\n",VTYPE(vec2),XC(vtx2),YC(vtx2));
}

/****************************************************************************/
/** \brief Prepare GetBoundaryNeighbourVectors

 * @param theGrid - grid level
 * @param MaxListLen - max size of neighbourhood and therefore max list lenght of the
   VecList array of GetBoundaryNeighbourVectors

   This function stores lists of boundary vector neighbourhoods in temp storage
   of the multigrid. The neighborhoods of the boundary vectors can be received
   via a call of GetBoundaryNeighbourVectors one by one.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   >0 else </li>
   </ul>

 * \sa
   GetBoundaryNeighbourVectors, ResetGetBoundaryNeighbourVectors, FinishBoundaryNeighbourVectors
 */
/****************************************************************************/

INT NS_DIM_PREFIX PrepareGetBoundaryNeighbourVectors (GRID *theGrid, INT *MaxListLen)
{
#ifdef __TWODIM__
  ELEMENT *elem;
  VECTOR *vec,*v0,*v1;
  INT i;

  if (GBNV_list!=NULL)
    /* last process not finished properly by call of GetBoundaryNeighbourVectors */
    REP_ERR_RETURN(1);

  /* count boundary node vectors */
  GBNV_n = 0;
  for (vec=FIRSTVECTOR(theGrid); vec!=NULL; vec=SUCCVC(vec))
    if (VOTYPE(vec)==NODEVEC)
      if (OBJT(MYVERTEX((NODE*)VOBJECT(vec)))==BVOBJ)
        GBNV_n++;

  /* allocate list storage: 3 pointers each */
  GBNV_mg = MYMG(theGrid);
  MarkTmpMem(MGHEAP(GBNV_mg),&GBNV_MarkKey);
  GBNV_list = (VECTOR **) GetTmpMem(MGHEAP(GBNV_mg),3*GBNV_n*sizeof(VECTOR *),GBNV_MarkKey);
  if (GBNV_list==NULL)
    REP_ERR_RETURN(1);

  /* store offset in vector index field */
  i = 0;
  for (vec=FIRSTVECTOR(theGrid); vec!=NULL; vec=SUCCVC(vec))
    if (VOTYPE(vec)==NODEVEC)
      if (OBJT(MYVERTEX((NODE*)VOBJECT(vec)))==BVOBJ)
      {
        VINDEX(vec) = i;
        GBNV_list[i] = vec;
        i += 3;
      }

  /* loop elements and fill neighbours */
  /* TODO: parallel also orphan(?) elements to be complete */
  for (elem=FIRSTELEMENT(theGrid); elem!=NULL; elem=SUCCE(elem))
    if (OBJT(elem)==BEOBJ)
      for (i=0; i<SIDES_OF_ELEM(elem); i++)
        if (ELEM_BNDS(elem,i)!=NULL)
        {
          /* 2D: two corners */
          v0 = NVECTOR(CORNER(elem,CORNER_OF_SIDE(elem,i,0)));
          v1 = NVECTOR(CORNER(elem,CORNER_OF_SIDE(elem,i,1)));

          ASSERT(GBNV_list[VINDEX(v0)]==v0);
          ASSERT(GBNV_list[VINDEX(v1)]==v1);
          GBNV_list[VINDEX(v0)+2] = v1;
          GBNV_list[VINDEX(v1)+1] = v0;
        }
  GBNV_curr = 0;

  /* this is simple in 2D: center, pred and succ in positive sense */
  *MaxListLen = 3;

  IFDEBUG(gm,2)
  PrintDebug("PrepareGetBoundaryNeighbourVectors:\n");
  for (i=0; i<GBNV_n; i++)
    PrintVectorTriple(3*i);
  ENDDEBUG

  return (0);

#endif /* __TWODIM__ */

#ifdef __THREEDIM__
  /* 3D requires somewhat more work! */

  /* but it should be possible to create an oriented list
     of neighbours for each boundary vector */

  REP_ERR_RETURN (1);
#endif /* __THREEDIM__ */
}

/****************************************************************************/
/** \brief Reset current neighbourhood to begin of list

   This function resets the pointer to the current neighbourhood to the beginning of
   the list. GetBoundaryNeighbourVectors will start again with the first one.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   >0 else </li>
   </ul>

 * \sa
   GetBoundaryNeighbourVectors, PrepareGetBoundaryNeighbourVectors, FinishBoundaryNeighbourVectors
 */
/****************************************************************************/

INT NS_DIM_PREFIX ResetGetBoundaryNeighbourVectors (void)
{
  if (GBNV_list==NULL)
    REP_ERR_RETURN(1);

  GBNV_curr = 0;
  return (0);
}

/****************************************************************************/
/** \brief Get a neighbourhood of boundary vectors

 * @param dt - datatypes of center vectors (bitwise)
 * @param obj - object types of center vectors (bitwise)
 * @param cnt - vector list length
 * @param VecList - vector list
 * @param end - if YES the currently returned list was the last one

   This function returns a neighbourhood of boundary vectors, center first and the
   remainder oriented in positiv sense. The boundary vector heighbourhood lists
   are created by a call of PrepareGetBoundaryNeighbourVectors. Use
   ResetGetBoundaryNeighbourVectors to begin again with the first
   neighbourhood and finish processing the boundary vectors with a call of
   FinishBoundaryNeighbourVectors which releases the temporary storage
   occupied by PrepareGetBoundaryNeighbourVectors..

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   >0 else </li>
   </ul>
 * \sa
   PrepareGetBoundaryNeighbourVectors, ResetGetBoundaryNeighbourVectors, FinishBoundaryNeighbourVectors
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetBoundaryNeighbourVectors (INT dt, INT obj, INT *cnt, VECTOR *VecList[])
{
  VECTOR *vec;

  *cnt = 0;

  if (GBNV_list==NULL)
    REP_ERR_RETURN(1);

  /* find next center vec matching data type */
  for (vec=GBNV_list[GBNV_curr]; GBNV_curr<3*GBNV_n; GBNV_curr+=3, vec=GBNV_list[GBNV_curr])
    if (BITWISE_TYPE(VTYPE(vec)) & dt)
      break;
  if (GBNV_curr>=3*GBNV_n)
    /* no (more) vector found */
    return (0);

  if (VOTYPE(vec)!=NODEVEC)
    REP_ERR_RETURN(1);

  IFDEBUG(gm,2)
  PrintDebug("GetBoundaryNeighbourVectors:\n");
  PrintVectorTriple(GBNV_curr);
  ENDDEBUG

  /* vector, pre and succ in positive sense */
    VecList[(*cnt)++] = GBNV_list[GBNV_curr];
  VecList[(*cnt)++] = GBNV_list[GBNV_curr+1];
  VecList[(*cnt)++] = GBNV_list[GBNV_curr+2];

  /* move on to next position */
  GBNV_curr += 3;

  return (0);
}

/****************************************************************************/
/** \brief Finish processing of boundary vectors

   This function releases the temporary memory allocated by PrepareGetBoundaryNeighbourVectors
   from the multigrid heap.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   >0 else </li>
   </ul>

 * \sa
   PrepareGetBoundaryNeighbourVectors, ResetGetBoundaryNeighbourVectors, GetBoundaryNeighbourVectors
 */
/****************************************************************************/

INT NS_DIM_PREFIX FinishBoundaryNeighbourVectors ()
{
        #ifdef __TWODIM
  if (ReleaseTmpMem(MGHEAP(GBNV_mg)),GBNV_MarkKey)
    REP_ERR_RETURN(1);
        #endif

  GBNV_list = NULL;

  return (0);
}

/****************************************************************************/
/** \brief Get vector list

 * @param theGrid - pointer to a grid
 * @param theElement - pointer to an element
 * @param vec - vector list

   This function gets a list of vectors corresponding to an element.

 * @return <ul>
 *   <li>   number of components </li>
 *   <li>   -1 if error occured </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GetAllVectorsOfElement (GRID *theGrid, ELEMENT *theElement, VECTOR **vec)
{
  INT i;
  INT cnt;

  cnt = 0;
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,NODEVEC))
  {
    if (GetVectorsOfNodes(theElement,&i,vec) == GM_ERROR)
      RETURN(-1);
    cnt += i;
  }
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
  {
    if (GetVectorsOfEdges(theElement,&i,vec+cnt) == GM_ERROR)
      RETURN(-1);
    cnt += i;
  }
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,ELEMVEC))
  {
    if (GetVectorsOfElement(theElement,&i,vec+cnt) == GM_ERROR)
      RETURN(-1);
    cnt += i;
  }
    #ifdef __THREEDIM__
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
  {
    if (GetVectorsOfSides(theElement,&i,vec+cnt) == GM_ERROR)
      RETURN(-1);
    cnt += i;
  }
    #endif

  return (cnt);
}

/****************************************************************************/
/** \brief Remove all extra connections from the grid

 * @param theGrid - grid to remove from

   This function removes all extra connections from the grid, i.e. those
   that have been allocated with the CreateExtraConnection function.

 * @return <ul>
 *   <li>      0 if ok
 *   <li>      1 if error occured
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX DisposeExtraConnections (GRID *theGrid)
{
  VECTOR *theVector;
  MATRIX *theMatrix, *nextMatrix;
  CONNECTION *theCon;

  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
  {
    theMatrix = VSTART(theVector);
    while (theMatrix!=NULL)
    {
      nextMatrix = MNEXT(theMatrix);
      theCon = MMYCON(theMatrix);
      if (CEXTRA(theCon)) DisposeConnection(theGrid,theCon);
      theMatrix = nextMatrix;
    }
  }
  return(GM_OK);
}

INT NS_DIM_PREFIX DisposeConnectionsInGrid (GRID *theGrid)
{
  VECTOR *theVector;
  MATRIX *theMatrix, *nextMatrix;
  CONNECTION *theCon;

  for (theVector=PFIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
  {
    theMatrix = VSTART(theVector);
    while (theMatrix!=NULL)
    {
      nextMatrix = MNEXT(theMatrix);
      theCon = MMYCON(theMatrix);
      DisposeConnection(theGrid,theCon);
      theMatrix = nextMatrix;
    }
  }
  return(GM_OK);
}

/****************************************************************************/
/** \brief Create connections of two elements

 * @param theGrid - pointer to grid
 * @param Elem0,Elem1 - elements to be connected
 * @param ActDepth - distance of the two elements in the element neighborship graph
 * @param ConDepth - Array containing the connection depth desired
 * @param MatSize - Array containing the connection size. This is constructed from the information in the FORMAT.

   This function creates connections between all the VECTORs associated
   with two given elements according to the specifications in the ConDepth array.

 * @return <ul>
 *   <li>   0 if ok
 *   <li>   1 if error occured.
   </ul>
 */
/****************************************************************************/

static INT ElementElementCreateConnection (GRID *theGrid, ELEMENT *Elem0, ELEMENT *Elem1, INT ActDepth, INT *ConDepth, INT *MatSize)
{
  INT cnt0,cnt1,i,j,itype,jtype,mtype,size;
  VECTOR *vec0[MAX_SIDES_OF_ELEM+MAX_EDGES_OF_ELEM+MAX_CORNERS_OF_ELEM+1];
  VECTOR *vec1[MAX_SIDES_OF_ELEM+MAX_EDGES_OF_ELEM+MAX_CORNERS_OF_ELEM+1];

  cnt0 = GetAllVectorsOfElement(theGrid,Elem0,vec0);
  if (Elem0 == Elem1)
  {
    for (i=0; i<cnt0; i++)
    {
      itype=VTYPE(vec0[i]);
      for (j=i; j<cnt0; j++)
      {
        if (i==j)
        {
          mtype = DIAGMATRIXTYPE(itype);
          size  = MatSize[mtype];
        }
        else
        {
          jtype = VTYPE(vec0[j]);
          size  = MatSize[MATRIXTYPE(jtype,itype)];
          mtype = MATRIXTYPE(itype,jtype);
          if (MatSize[mtype]>size) size=MatSize[mtype];
        }
        if (size > 0)
          if (ActDepth <= ConDepth[mtype])
            if (CreateConnection(theGrid,vec0[i],vec0[j])==NULL)
              RETURN(GM_ERROR);
      }
    }
    if (NELIST_DEF_IN_GRID(theGrid))
      for (i=0; i<CORNERS_OF_ELEM(Elem0); i++)
        if (CreateElementList(theGrid,CORNER(Elem0,i),Elem0))
          RETURN(GM_ERROR);

    return (0);
  }

  cnt1 = GetAllVectorsOfElement(theGrid,Elem1,vec1);
  for (i=0; i<cnt0; i++)
  {
    itype=VTYPE(vec0[i]);
    for (j=0; j<cnt1; j++)
    {
      if (vec0[i]==vec1[j])
      {
        mtype = DIAGMATRIXTYPE(itype);
        size  = MatSize[mtype];
      }
      else
      {
        jtype = VTYPE(vec1[j]);
        size  = MatSize[MATRIXTYPE(jtype,itype)];
        mtype = MATRIXTYPE(itype,jtype);
        if (MatSize[mtype]>size) size=MatSize[mtype];
      }
      if (size > 0)
        if (ActDepth <= ConDepth[mtype])
          if (CreateConnection(theGrid,vec0[i],vec1[j])==NULL)
            RETURN(GM_ERROR);
    }
  }

  return (0);
}

/****************************************************************************/
/** \brief Get pointers to elements having a common side

 * @param theVector - given vector associated with a side of an element in 3D
 * @param Elements - array to be filled with two pointers of elements
 * @param Sides - array to be filled with side number within respective element

   Given a VECTOR associated with the side of an element, this function
   retrieves pointers to at most two elements having this side in common.
   If the side is part of the exterior boundary of the domain, then
   Elements[1] will be the NULL pointer.

 * @return <ul>
 *   <li>    0 if ok
 *   <li>    1 if error occured.
   </ul>
 */
/****************************************************************************/

#ifdef __THREEDIM__
INT NS_DIM_PREFIX GetElementInfoFromSideVector (const VECTOR *theVector, ELEMENT **Elements, INT *Sides)
{
  INT i;
  ELEMENT *theNeighbor;

  if (VOTYPE(theVector) != SIDEVEC)
    RETURN (1);
  Elements[0] = (ELEMENT *)VOBJECT(theVector);
  Sides[0] = VECTORSIDE(theVector);

  /* find neighbor */
  Elements[1] = theNeighbor = NBELEM(Elements[0],Sides[0]);
  if (theNeighbor == NULL) return (0);

  /* search the side */
  for (i=0; i<SIDES_OF_ELEM(theNeighbor); i++)
    if (NBELEM(theNeighbor,i) == Elements[0])
      break;

  /* found ? */
  if (i<SIDES_OF_ELEM(theNeighbor))
  {
    Sides[1] = i;
    return (0);
  }
  RETURN (1);
}
#endif

/****************************************************************************/
/** \brief Reset all USED flags in neighborhood of an element

 * @param theElement - given element
 * @param ActDepth - recursion depth
 * @param MaxDepth - end of recursion

   This function calls itself recursively and resets all USED flags in the
   neighborhood of depth MaxDepth of theElement. For the first call
   ActDepth should be zero.

 * @return <ul>
 *   <li>   0 if ok
 *   <li>   1 if error occured.
   </ul>
 */
/****************************************************************************/

static INT ResetUsedFlagInNeighborhood (ELEMENT *theElement, INT ActDepth, INT MaxDepth)
{
  int i;

  /* is anything to do ? */
  if (theElement==NULL) return (0);

  /* action */
  if (ActDepth>=0) SETUSED(theElement,0);

  /* call all neighbors recursively */
  if (ActDepth<MaxDepth)
    for (i=0; i<SIDES_OF_ELEM(theElement); i++)
      if (ResetUsedFlagInNeighborhood(NBELEM(theElement,i),ActDepth+1,MaxDepth)) RETURN (1);

  return (0);
}

static INT ConnectWithNeighborhood (ELEMENT *theElement, GRID *theGrid, ELEMENT *centerElement, INT *ConDepth, INT *MatSize, INT ActDepth, INT MaxDepth)
{
  int i;

  /* is anything to do ? */
  if (theElement==NULL) return (0);

  /* action */
  if (ActDepth>=0)
    if (ElementElementCreateConnection(theGrid,centerElement,theElement,
                                       ActDepth,ConDepth,MatSize))
      RETURN (1);

  /* call all neighbors recursively */
  if (ActDepth<MaxDepth)
    for (i=0; i<SIDES_OF_ELEM(theElement); i++)
      if (ConnectWithNeighborhood(NBELEM(theElement,i),theGrid,
                                  centerElement,ConDepth,MatSize,
                                  ActDepth+1,MaxDepth)) RETURN (1);

  return (0);
}

/****************************************************************************/
/** \brief Create connection of an element

 * @param theGrid - pointer to grid
 * @param theElement - pointer to an element

   This function creates connection for all VECTORs of an element
   with the depth specified in the FORMAT structure.

 * @return <ul>
 *   <li>   0 if ok
 *   <li>   1 if error occured.
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX CreateConnectionsInNeighborhood (GRID *theGrid, ELEMENT *theElement)
{
  FORMAT *theFormat;
  INT MaxDepth;
  INT *ConDepth;
  INT *MatSize;

  /* set pointers */
  theFormat = GFORMAT(theGrid);
  MaxDepth = FMT_CONN_DEPTH_MAX(theFormat);
  ConDepth = FMT_CONN_DEPTH_PTR(theFormat);
  MatSize = FMT_S_MATPTR(theFormat);

  /* reset used flags in neighborhood */
  if (ResetUsedFlagInNeighborhood(theElement,0,MaxDepth))
    RETURN (1);

  /* create connection in neighborhood */
  if (ConnectWithNeighborhood(theElement,theGrid,theElement,ConDepth,
                              MatSize,0,MaxDepth))
    RETURN (1);

  return (0);
}

/****************************************************************************/
/** \brief Create connection of an inserted element

   This function creates connection of an inserted element ,
   i.e. an element is inserted interactively by the user.

 * @return <ul>
 *   <li>   0 if ok
 *   <li>   1 if error occured.
   </ul>
 */
/****************************************************************************/

static INT ConnectInsertedWithNeighborhood (ELEMENT *theElement, GRID *theGrid, INT ActDepth, INT MaxDepth)
{
  int i;

  /* is anything to do ? */
  if (theElement==NULL) return (0);

  /* action */
  if (ActDepth>=0)
    if (CreateConnectionsInNeighborhood(theGrid,theElement))
      RETURN (1);

  /* call all neighbors recursively */
  if (ActDepth<MaxDepth)
    for (i=0; i<SIDES_OF_ELEM(theElement); i++)
      if (ConnectInsertedWithNeighborhood(NBELEM(theElement,i),theGrid,ActDepth+1,MaxDepth)) RETURN (1);

  return (0);
}

/****************************************************************************/
/** \brief Create connection of an inserted element

 * @param theGrid - grid level
 * @param theElement -  pointer to an element

   This function creates connections of an inserted element ,
   i.e. when an element is inserted interactively by the user. This function
   is inefficient and only intended for that purpose.

 * @return <ul>
 *   <li>  0 if ok
 *   <li>  1 if error occured.
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX InsertedElementCreateConnection (GRID *theGrid, ELEMENT *theElement)
{
  FORMAT *theFormat;
  INT MaxDepth;

  if (!MG_COARSE_FIXED(MYMG(theGrid)))
    RETURN (1);

  /* set pointers */
  theFormat = GFORMAT(theGrid);
  MaxDepth = (INT)(floor(0.5*(double)FMT_CONN_DEPTH_MAX(theFormat)));

  /* reset used flags in neighborhood */
  if (ResetUsedFlagInNeighborhood(theElement,0,MaxDepth))
    RETURN (1);

  /* call 'CreateConnectionsInNeighborhood'
     in a neighborhood of theElement */
  if (ConnectInsertedWithNeighborhood (theElement,theGrid,0,MaxDepth))
    RETURN (1);

  return (0);
}

/****************************************************************************/
/** \brief Create all connections needed on a grid level

 * @param theGrid - pointer to grid

   This function creates all connections needed on the grid.

 * @return <ul>
 *   <li>    0 if ok
 *   <li>    1 if error occured.
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX GridCreateConnection (GRID *theGrid)
{
  ELEMENT *theElement;
  VECTOR *vList[20];
  INT i,cnt;

#if defined(ModelP) and defined(__THREEDIM__)
  auto& dddContext = theGrid->dddContext();
#endif

  if (!MG_COARSE_FIXED(MYMG(theGrid)))
    RETURN (1);

  /* lets see if there's something to do */
  if (theGrid == NULL)
    return (0);

#if defined(ModelP) and defined(__THREEDIM__)
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
    DDD_XferBegin(dddContext);
#endif

  /* set EBUILDCON-flags also in elements accessing a vector with VBUILDCON true */
  for (theElement=PFIRSTELEMENT(theGrid); theElement!=NULL; theElement=SUCCE(theElement))
  {
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
    {
      EDGE *ed;

      for (i=0; i<EDGES_OF_ELEM(theElement); i++) {
        ed = GetEdge(CORNER(theElement,
                            CORNER_OF_EDGE(theElement,i,0)),
                     CORNER(theElement,
                            CORNER_OF_EDGE(theElement,i,1)));
        ASSERT (ed != NULL);
        if (EDVECTOR(ed) == NULL) {
          CreateVector(theGrid,EDGEVEC,(GEOM_OBJECT *)ed,vList);
          EDVECTOR(ed) = vList[0];
#if defined(ModelP) and defined(__THREEDIM__)
          SETPRIO(dddContext, EDVECTOR(ed),PRIO(ed));
#endif
        }
      }
    }

            #ifdef ModelP
    if (!EMASTER(theElement)) continue;
                #endif

    /* see if it is set */
    if (EBUILDCON(theElement)) continue;

    /* check flags in vectors */
                #ifdef __THREEDIM__
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
    {
      GetVectorsOfSides(theElement,&cnt,vList);
      for (i=0; i<cnt; i++)
        if (VBUILDCON(vList[i])) {SETEBUILDCON(theElement,1); break;}
    }
    if (EBUILDCON(theElement)) continue;
        #endif
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
    {
      GetVectorsOfEdges(theElement,&cnt,vList);
      for (i=0; i<cnt; i++)
        if (VBUILDCON(vList[i])) {SETEBUILDCON(theElement,1); break;}
    }
    if (EBUILDCON(theElement)) continue;
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,NODEVEC))
    {
      GetVectorsOfNodes(theElement,&cnt,vList);
      for (i=0; i<cnt; i++)
        if (VBUILDCON(vList[i])) {SETEBUILDCON(theElement,1); break;}
    }
  }

#if defined(ModelP) and defined(__THREEDIM__)
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
    DDD_XferEnd(theGrid->dddContext());
#endif

  /* run over all elements with EBUILDCON true and build connections */
  for (theElement=FIRSTELEMENT(theGrid); theElement!=NULL;
       theElement=SUCCE(theElement))
    if (EBUILDCON(theElement))             /* this is the trigger ! */
      if (CreateConnectionsInNeighborhood(theGrid,theElement))
        RETURN (1);

  return(GM_OK);
}


#ifdef ModelP
static int Gather_VectorVNew (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  ((INT *)data)[0] = VNEW(theVector);

  return(0);
}

static int Scatter_VectorVNew (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  SETVNEW(theVector,MAX(VNEW(theVector),((INT *)data)[0]));

  return(0);
}

static int Scatter_GhostVectorVNew (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  SETVNEW(theVector,((INT *)data)[0]);

  return(0);
}
#endif

INT NS_DIM_PREFIX SetSurfaceClasses (MULTIGRID *theMG)
{
  GRID *theGrid;
  ELEMENT *theElement;        VECTOR *v;
  INT level,fullrefine;

  level = TOPLEVEL(theMG);
  if (level > 0) {
    theGrid = GRID_ON_LEVEL(theMG,TOPLEVEL(theMG));
    ClearVectorClasses(theGrid);
    for (theElement=PFIRSTELEMENT(theGrid); theElement!=NULL;
         theElement=SUCCE(theElement))
    {
      if (MinNodeClass(theElement)==3)
        SeedVectorClasses(theGrid,theElement);
    }
    PropagateVectorClasses(theGrid);
    theGrid = GRID_ON_LEVEL(theMG,0);
    ClearNextVectorClasses(theGrid);
    for (theElement=PFIRSTELEMENT(theGrid); theElement!=NULL;
         theElement=SUCCE(theElement))
    {
      if (MinNextNodeClass(theElement)==3)
        SeedNextVectorClasses(theGrid,theElement);
    }
    PropagateNextVectorClasses(theGrid);
  }
  for (level--; level>0; level--)
  {
    theGrid = GRID_ON_LEVEL(theMG,level);
    ClearVectorClasses(theGrid);
    ClearNextVectorClasses(theGrid);
    for (theElement=PFIRSTELEMENT(theGrid); theElement!=NULL;
         theElement=SUCCE(theElement)) {
      if (MinNodeClass(theElement)==3)
        SeedVectorClasses(theGrid,theElement);
      if (MinNextNodeClass(theElement)==3)
        SeedNextVectorClasses(theGrid,theElement);
    }
    PropagateVectorClasses(theGrid);
    PropagateNextVectorClasses(theGrid);
  }

  fullrefine = TOPLEVEL(theMG);
  for (level=TOPLEVEL(theMG); level>=BOTTOMLEVEL(theMG); level--)
  {
    theGrid = GRID_ON_LEVEL(theMG,level);
    for (v=PFIRSTVECTOR(theGrid); v!= NULL; v=SUCCVC(v)) {
      SETNEW_DEFECT(v,(VCLASS(v)>=2));
      SETFINE_GRID_DOF(v,((VCLASS(v)>=2)&&(VNCLASS(v)<=1)));
      if (FINE_GRID_DOF(v))
        fullrefine = level;
    }
  }
        #ifdef ModelP
  fullrefine = UG_GlobalMinINT(theMG->ppifContext(), fullrefine);
        #endif

  FULLREFINELEVEL(theMG) = fullrefine;

  return(0);
}

/****************************************************************************/
/** \brief Creates the algebra for a grid

 * @param theGrid - pointer to grid

   This function allocates VECTORs in all geometrical objects of the grid
   (where described by format) and then calls GridCreateConnection.

 * @return <ul>
 *   <li>    GM_OK if ok
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX CreateAlgebra (MULTIGRID *theMG)
{
  GRID *g;
  FORMAT *fmt;
  VECTOR *vec;
#ifdef __THREEDIM__
  VECTOR *nbvec;
  ELEMENT *nbelem;
  INT j,n;
#endif
  ELEMENT *elem;
  NODE *nd;
  LINK *li;
  EDGE *ed;
  INT side,i;


  if (MG_COARSE_FIXED(theMG) == false) {
    for (i=0; i<=TOPLEVEL(theMG); i++) {
      g = GRID_ON_LEVEL(theMG,i);

      if (NVEC(g)>0)
        continue;                               /* skip this level */

      fmt = MGFORMAT(MYMG(g));

      /* loop nodes and edges */
      for (nd=PFIRSTNODE(g); nd!=NULL; nd=SUCCN(nd)) {
        /* node vector */
        if (FMT_USES_OBJ(fmt,NODEVEC))
        {
          ASSERT(NVECTOR(nd)==NULL);
          if (CreateVector (g,NODEVEC,(GEOM_OBJECT *)nd,&vec))
            REP_ERR_RETURN (GM_ERROR);
          NVECTOR(nd) = vec;
        }

        /* edge vectors */
        if (FMT_USES_OBJ(fmt,EDGEVEC))
          for (li=START(nd); li!=NULL; li=NEXT(li)) {
            ed = MYEDGE(li);
            if (li==LINK0(ed))                                     /* to avoid double access of edges*/
            {
              ASSERT(EDVECTOR(ed)==NULL);
              if (CreateVector(g,EDGEVEC,(GEOM_OBJECT *)ed,&vec))
                REP_ERR_RETURN (GM_ERROR);
              EDVECTOR(ed) = vec;
            }
          }
      }

      /* loop elements and element sides */
      for (elem=PFIRSTELEMENT(g); elem!=NULL; elem=SUCCE(elem)) {
        /* to tell GridCreateConnection to build connections */
        if (EMASTER(elem)) SETEBUILDCON(elem,1);

        /* element vector */
        if (FMT_USES_OBJ(fmt,ELEMVEC)) {
          ASSERT(EVECTOR(elem)==NULL);
          if (CreateVector (g,ELEMVEC,(GEOM_OBJECT *)elem,&vec))
            REP_ERR_RETURN (GM_ERROR);
          SET_EVECTOR(elem,vec);
        }

        /* side vectors */
        if (FMT_USES_OBJ(fmt,SIDEVEC))
          for (side=0; side<SIDES_OF_ELEM(elem); side++)
            if (SVECTOR(elem,side)==NULL) {
              if (CreateSideVector (g,side,
                                    (GEOM_OBJECT *)elem,&vec))
                REP_ERR_RETURN (GM_ERROR);
              SET_SVECTOR(elem,side,vec);
            }
      }
    }
#ifdef __THREEDIM__
    /* dispose doubled side vectors */
    if (FMT_USES_OBJ(fmt,SIDEVEC))
      for (elem=PFIRSTELEMENT(g); elem!=NULL; elem=SUCCE(elem))
      {
        for(side=0; side<SIDES_OF_ELEM(elem); side++)
        {
          if(OBJT(elem)==BEOBJ)
          {
            if(INNER_SIDE(elem,side))
            {
              nbelem = NBELEM(elem,side);
              ASSERT(nbelem!=NULL);
              vec=SVECTOR(elem,side);
              n=0;
              for(j=0; j<SIDES_OF_ELEM(nbelem); j++)
              {
                nbvec=SVECTOR(nbelem,j);

                /* doubled sidevectors ? */
                if(NBELEM(nbelem,j)==elem)
                {
                  if(vec!=nbvec)
                  {
                    if(DisposeVector(g,nbvec))
                      REP_ERR_RETURN(GM_ERROR);
                    SET_SVECTOR(nbelem,j,vec);
                    SETVCOUNT(vec,2);                                                                     /* PB, 25 Sep 2005: changed from 1 to 2 */
                  }
                }
              }
              n++;
              ASSERT(n==1);
            }
          }else
          {
            nbelem = NBELEM(elem,side);
            ASSERT(nbelem!=NULL);
            vec=SVECTOR(elem,side);
            n=0;
            for(j=0; j<SIDES_OF_ELEM(nbelem); j++)
            {
              nbvec=SVECTOR(nbelem,j);
              ASSERT(nbvec!=NULL);

              /* doubled sidevectors ? */
              if(NBELEM(nbelem,j)==elem)
              {
                if(vec!=nbvec)
                {
                  if(DisposeVector(g,nbvec))
                    REP_ERR_RETURN(GM_ERROR);
                  SET_SVECTOR(nbelem,j,vec);
                  SETVCOUNT(vec,2);                                                               /* PB, 25 Sep 2005: changed from 1 to 2 */
                }
              }
            }
            n++;
            ASSERT(n==1);
          }
        }
      }
#endif
    MG_COARSE_FIXED(theMG) = true;

    /* now connections */
    if (MGCreateConnection(theMG))
      REP_ERR_RETURN (1);
  }

  /* now we should be safe to clear the InsertElement face map */
  theMG->facemap.clear();

    #ifdef ModelP
    #ifndef __EXCHANGE_CONNECTIONS__
  MGCreateConnection(theMG);
    #endif
  /* update VNEW-flags */
  auto& context = theMG->dddContext();
  const auto& dddctrl = ddd_ctrl(context);
  DDD_IFExchange(context,
                 dddctrl.BorderVectorSymmIF,sizeof(INT),
                 Gather_VectorVNew,Scatter_VectorVNew);
  DDD_IFOneway(context,
               dddctrl.VectorIF,IF_FORWARD,sizeof(INT),
               Gather_VectorVNew,Scatter_GhostVectorVNew);
    #else
  MGCreateConnection(theMG);
    #endif

    #ifdef __PERIODIC_BOUNDARY__
  IFDEBUG(gm,1)
  INT i;

  for (i=0; i<=TOPLEVEL(theMG); i++)
    if (Grid_CheckPeriodicity(GRID_ON_LEVEL(theMG,i)))
      return (GM_ERROR);
  ENDDEBUG
    #endif

  SetSurfaceClasses(theMG);

  return(GM_OK);
}

/****************************************************************************/
/** \brief Create all connections in multigrid

 * @param theMG - pointer to mulrigrid

   This function creates all connections in multigrid.

 * @return <ul>
 *   <li>    0 if ok
 *   <li>    1 if error occured.
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX MGCreateConnection (MULTIGRID *theMG)
{
  INT i;
  GRID *theGrid;
  ELEMENT *theElement;

  if (!MG_COARSE_FIXED(theMG))
    RETURN (1);

  for (i=0; i<=theMG->topLevel; i++)
  {
    theGrid = GRID_ON_LEVEL(theMG,i);
    for (theElement=FIRSTELEMENT(theGrid); theElement!=NULL; theElement=SUCCE(theElement))
      SETEBUILDCON(theElement,1);
    if (GridCreateConnection(theGrid)) RETURN (1);
  }

  return (0);
}


INT NS_DIM_PREFIX PrepareAlgebraModification (MULTIGRID *theMG)
{
  int j,k;
  ELEMENT *theElement;
  VECTOR *theVector;
  MATRIX *theMatrix;

  j = theMG->topLevel;
  for (k=0; k<=j; k++)
  {
    for (theElement=PFIRSTELEMENT(GRID_ON_LEVEL(theMG,k)); theElement!=NULL; theElement=SUCCE(theElement))
    {
      SETUSED(theElement,0);
      SETEBUILDCON(theElement,0);
    }
    for (theVector=PFIRSTVECTOR(GRID_ON_LEVEL(theMG,k)); theVector!= NULL; theVector=SUCCVC(theVector))
      SETVBUILDCON(theVector,0);
    for (theVector=PFIRSTVECTOR(GRID_ON_LEVEL(theMG,k)); theVector!= NULL; theVector=SUCCVC(theVector))
    {
      SETVNEW(theVector,0);
      for (theMatrix=VSTART(theVector); theMatrix!=NULL; theMatrix = MNEXT(theMatrix))
        SETMNEW(theMatrix,0);
    }
  }

  return (0);
}

/****************************************************************************/
/** \brief Check connection of two elements

 * @param theGrid -  grid level to check
 * @param Elem0,Elem1 - elements to be checked.
 * @param ActDepth - recursion depth
 * @param ConDepth - connection depth as provided by format.
 * @param MatSize - matrix sizes as provided by format

   This function recursively checks connection of two elements.

 * @return <ul>
 *   <li>    0 if ok
 *   <li>    != 0 if errors occured.
   </ul>
 */
/****************************************************************************/

static INT ElementElementCheck (GRID *theGrid, ELEMENT *Elem0, ELEMENT *Elem1, INT ActDepth, INT *ConDepth, INT *MatSize)
{
  INT cnt0,cnt1,i,j,itype,jtype,mtype,size;
  VECTOR *vec0[MAX_SIDES_OF_ELEM+MAX_EDGES_OF_ELEM+MAX_CORNERS_OF_ELEM+1];
  VECTOR *vec1[MAX_SIDES_OF_ELEM+MAX_EDGES_OF_ELEM+MAX_CORNERS_OF_ELEM+1];
  CONNECTION *theCon;
  char msg[128];
  INT errors = 0;

  sprintf(msg, " ERROR: missing connection between elem0=" EID_FMTX " elem1=" EID_FMTX,
          EID_PRTX(Elem0),EID_PRTX(Elem1));

  cnt0 = GetAllVectorsOfElement(theGrid,Elem0,vec0);
  if (Elem0 == Elem1)
  {
    for (i=0; i<cnt0; i++)
    {
      itype=VTYPE(vec0[i]);
      for (j=0; j<cnt0; j++)
      {
        if (i==j)
        {
          mtype = DIAGMATRIXTYPE(itype);
          size  = MatSize[mtype];
        }
        else
        {
          jtype = VTYPE(vec0[j]);
          size  = MatSize[MATRIXTYPE(jtype,itype)];
          mtype = MATRIXTYPE(itype,jtype);
          if (MatSize[mtype]>size) size=MatSize[mtype];
        }
        if (size > 0)
          if (ActDepth <= ConDepth[mtype])
          {
            /* check connection in both directions */
            theCon = GetConnection(vec0[i],vec0[j]);
            if (theCon==NULL)
            {
              errors++;
              UserWriteF("%s vec0[%d]=" VINDEX_FMTX
                         " to vec0[%d]=" VINDEX_FMTX "\n",
                         msg,i,VINDEX_PRTX(vec0[i]),
                         j,VINDEX_PRTX(vec0[j]));
            }
            else
            {
              theCon = GetConnection(vec0[j],vec0[i]);
              if (theCon==NULL)
              {
                errors++;
                UserWriteF("%s vec0[%d]=" VINDEX_FMTX
                           " to vec0[%d]=" VINDEX_FMTX "\n",
                           msg,j,VINDEX_PRTX(vec0[j]),
                           i,VINDEX_PRTX(vec0[i]));
              }
              else
              {
                SETCUSED(theCon,1);
              }
            }
          }
      }
    }
    return (errors);
  }

  cnt1 = GetAllVectorsOfElement(theGrid,Elem1,vec1);
  for (i=0; i<cnt0; i++)
  {
    itype=VTYPE(vec0[i]);
    for (j=0; j<cnt1; j++)
    {
      if (i==j)
      {
        mtype = DIAGMATRIXTYPE(itype);
        size  = MatSize[mtype];
      }
      else
      {
        jtype = VTYPE(vec1[j]);
        size  = MatSize[MATRIXTYPE(jtype,itype)];
        mtype = MATRIXTYPE(itype,jtype);
        if (MatSize[mtype]>size) size=MatSize[mtype];
      }
      if (size > 0)
        if (ActDepth <= ConDepth[mtype])
        {
          /* check connection in both directions */
          theCon = GetConnection(vec0[i],vec1[j]);
          if (theCon==NULL)
          {
            errors++;
            UserWriteF("%s vec0[%d]=" VINDEX_FMTX
                       " to vec1[%d]=" VINDEX_FMTX "\n",
                       msg,i,VINDEX_PRTX(vec0[i]),
                       j,VINDEX_PRTX(vec1[j]));
          }
          else
          {
            theCon = GetConnection(vec1[j],vec0[i]);
            if (theCon == NULL)
            {
              errors++;
              UserWriteF("%s vec1[%d]=" VINDEX_FMTX
                         " to vec0[%d]=%x/" VINDEX_FMTX "\n",
                         msg,j,VINDEX_PRTX(vec1[j]),
                         i,VINDEX_PRTX(vec0[i]));
            }
            else
              SETCUSED(theCon,1);
          }
        }
    }
  }

  return (errors);
}

static INT CheckNeighborhood (GRID *theGrid, ELEMENT *theElement, ELEMENT *centerElement, INT *ConDepth, INT ActDepth, INT MaxDepth, INT *MatSize)
{
  INT i,errors = 0;

  /* is anything to do ? */
  if (theElement==NULL) return (0);

  /* action */
  if (ActDepth>=0)
    if ((errors+=ElementElementCheck(theGrid,centerElement,theElement,ActDepth,ConDepth,MatSize))!=0)
      return (errors);

  /* call all neighbors recursively */
  if (ActDepth<MaxDepth)
    for (i=0; i<SIDES_OF_ELEM(theElement); i++)
      if ((errors+=CheckNeighborhood(theGrid,NBELEM(theElement,i),centerElement,ConDepth,ActDepth+1,MaxDepth,MatSize))!=0)
        return(errors);

  return (0);
}

/****************************************************************************/
/** \brief Check connection of the element

 * @param theGrid - pointer to grid
 * @param theElement - pointer to element

   This function checks all connections of the given element.

 * @return <ul>
 *   <li>  number of errors
 *   <li>  0 if ok
 *   <li>  != 0 if errors occured in that connection.
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX ElementCheckConnection (GRID *theGrid, ELEMENT *theElement)
{
  FORMAT *theFormat;
  INT MaxDepth;
  INT *ConDepth;
  INT *MatSize;

  /* set pointers */
  theFormat = GFORMAT(theGrid);
  MaxDepth = FMT_CONN_DEPTH_MAX(theFormat);
  ConDepth = FMT_CONN_DEPTH_PTR(theFormat);
  MatSize = FMT_S_MATPTR(theFormat);

  /* call elements recursivly */
  return(CheckNeighborhood(theGrid,theElement,theElement,ConDepth,0,MaxDepth,MatSize));
}

/****************************************************************************/
/** \brief Check if connections are correctly allocated

 * @param theGrid -  grid level to check

   This function checks if connections are correctly allocated.

 * @return <ul>
 *   <li>    GM_OK if ok
 *   <li>    GM_ERROR	if error occured.
   </ul>
 */
/****************************************************************************/

static INT CheckConnections (GRID *theGrid)
{
  ELEMENT *theElement;
  INT errors;
  INT error;

  errors = 0;

  for (theElement=FIRSTELEMENT(theGrid);
       theElement!=NULL;
       theElement=SUCCE(theElement))
  {
    if ((error=ElementCheckConnection(theGrid,theElement))!=0)
    {
      UserWriteF("element=" EID_FMTX " has bad connections\n",
                 EID_PRTX(theElement));
      errors+=error;
    }
  }

  return(errors);
}


/****************************************************************************/
/** \brief Checks validity of geom_object	and its vector

 * @param fmt - FORMAT of associated multigrid
 * @param s2p - subdomain to part table
 * @param theObject - the object which points to theVector
 * @param ObjectString - for error message
 * @param theVector - the vector of theObject
 * @param VectorObjType - NODEVEC,...
 * @param side - element side for SIDEVEC, NOSIDE else

   This function checks the consistency between an geom_object and
   its vector.

 * @return <ul>
 *   <li>    GM_OK if ok
 *   <li>    GM_ERROR	if error occured.
   </ul>
 */
/****************************************************************************/

static INT CheckVector (const FORMAT *fmt, const INT s2p[], GEOM_OBJECT *theObject, const char *ObjectString,
                        VECTOR *theVector, INT VectorObjType, INT side)
{
  GEOM_OBJECT *VecObject;
  MATRIX *mat;
  INT errors = 0,vtype,DomPart,ds;

  if (theVector == NULL)
  {
    /* check if size is really 0 */
    DomPart = GetDomainPart(s2p,theObject,side);
    vtype = FMT_PO2T(fmt,DomPart,VectorObjType);
    ds = FMT_S_VEC_TP(fmt,vtype);
    if (ds>0)
    {
      errors++;
      UserWriteF("%s ID=%ld  has NO VECTOR", ObjectString,
                 ID(theObject));
                        #ifdef ModelP
                        #ifdef __THREEDIM__
      if (VectorObjType == EDGEVEC)
        UserWriteF(" prio=%d",PRIO((EDGE*)theObject));
                        #endif
                        #endif
      UserWrite("\n");
    }
  }
  else
  {
    ds = FMT_S_VEC_TP(fmt,VTYPE(theVector));
    if (ds==0)
    {
      errors++;
      UserWriteF("%s ID=%ld  exists but should not\n", ObjectString,
                 ID(theObject));
    }
    SETVCUSED(theVector,1);

    VecObject = VOBJECT(theVector);
    if (VecObject == NULL)
    {
      errors++;
      UserWriteF("vector=" VINDEX_FMTX " %s GID=" GID_FMT " has NO BACKPTR\n",
                 VINDEX_PRTX(theVector), ObjectString,
                 (OBJT(theObject)==BEOBJ || OBJT(theObject)==IEOBJ) ?
                 EGID(&(theObject->el)) : (OBJT(theObject)==NDOBJ) ?
                 GID(&(theObject->nd)) :
                 GID(&(theObject->ed))
                 );
    }
    else
    {
      if (VOTYPE(theVector) != VectorObjType)
      {
        errors++;
        UserWriteF("%s vector=" VINDEX_FMTX " has incompatible type=%d, "
                   "should be type=%s\n",
                   ObjectString, VINDEX_PRTX(theVector), VTYPE(theVector),
                   ObjTypeName[VectorObjType]);
      }

      if (VecObject != theObject)
      {
        if (OBJT(VecObject) != OBJT(theObject))
        {
          int error = 1;

          /* both objects may be elements */
          if ((OBJT(VecObject)==BEOBJ || OBJT(VecObject)==IEOBJ) &&
              (OBJT(theObject)==BEOBJ || OBJT(theObject)==IEOBJ) )
          {
            ELEMENT *theElement = (ELEMENT *)theObject;
            ELEMENT *vecElement = (ELEMENT *)VecObject;
            int i;

                                                #ifdef ModelP
            if (EMASTER(theElement) ||
                EMASTER(vecElement) )
            {
                                                #endif
            for (i=0; i<SIDES_OF_ELEM(theElement); i++)
              if (NBELEM(theElement,i) == vecElement)
              {
                /* they are neighbors -> ok */
                error = 0;
                break;
              }
                                                #ifdef ModelP
          }
                                                #endif
            if (error)
            {
              UserWriteF("vector=" VINDEX_FMTX " has type %s, but points "
                         "to wrong vecobj=" EID_FMTX " NO NB of obj=" EID_FMTX "\n",
                         VINDEX_PRTX(theVector),ObjectString,
                         EID_PRTX(vecElement),EID_PRTX(theElement));
            }
          }
          else
          {
            errors++;
            UserWriteF("vector=" VINDEX_FMTX " has type %s, but points "
                       "to wrong obj=%d type OBJT=%d\n",
                       VINDEX_PRTX(theVector),ObjectString,ID(VecObject),
                       OBJT(VecObject));
          }
        }
        else
        {
                                        #ifdef __THREEDIM__
          if (VectorObjType == SIDEVEC)
          {
            /* TODO: check side vector */
          }
          else
                                        #endif
                                        #ifndef __PERIODIC_BOUNDARY__
          {
            errors++;
            UserWriteF("%s vector=" VINDEX_FMTX " is referenced by "
                       "obj0=%x, but points to wrong obj1=%x\n",
                       ObjectString, VINDEX_PRTX(theVector),
                       theObject, VecObject);
                                                #ifdef ModelP
            if (strcmp(ObjectString,"EDGE")==0)
              UserWriteF("obj0: n0=%d n1=%d  obj1: "
                         "n0=%d n1=%d\n",
                         GID(NBNODE(LINK0(&(theObject->ed)))),
                         GID(NBNODE(LINK1(&(theObject->ed)))),
                         GID(NBNODE(LINK0(&(VecObject->ed)))),
                         GID(NBNODE(LINK1(&(VecObject->ed)))) );
                                                #endif
          }
                                        #else
          /* TODO: check whether reference to node is valid */
          if (HEAPCHECK(VecObject) || VecObject==NULL)
            UserWriteF("%s vector=" VINDEX_FMTX " is referenced by "
                       "obj0=%x, but points to ZOMBIE obj1=%x\n",
                       ObjectString, VINDEX_PRTX(theVector),
                       theObject, VecObject);
                                        #endif
        }
      }
    }
    /* check connectivity of matrices */
    for (mat=VSTART(theVector); mat!=NULL; mat=MNEXT(mat))
      if (MDEST(mat)==NULL)
      {
        errors++;
        UserWriteF("%s vector=" VINDEX_FMTX ": matrix dest==NULL\n",
                   ObjectString, VINDEX_PRTX(theVector));
      }
      else if (MDEST(MADJ(mat))!=theVector)
      {
        errors++;
        UserWriteF("%s vector=" VINDEX_FMTX ": adj matrix dest does not coincide"
                   " with vector conn=%x mat=%x mdest=%x\n",
                   ObjectString, VINDEX_PRTX(theVector),MMYCON(mat),MDEST(mat),MDEST(MADJ(mat)));
      }

  }

  return(errors);
}

/****************************************************************************/
/** \brief Check the algebraic part of the data structure

 * @param theGrid -  grid level to check

   This function checks the consistency of the algebraic data structures
   including the interconnections between the geometric part.
   This function assumes a correct geometric data structure.

 * @return <ul>
 *   <li>    GM_OK if ok </li>
 *   <li>    GM_ERROR	if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX CheckAlgebra (GRID *theGrid)
{
  FORMAT *fmt;
  ELEMENT *theElement;
  NODE *theNode;
  VECTOR *theVector;
  EDGE *theEdge;
  LINK *theLink;
  INT errors;
  INT *s2p;
#       ifdef __THREEDIM__
  INT i;
#       endif

  errors = 0;

  if ((GLEVEL(theGrid)==0) && !MG_COARSE_FIXED(MYMG(theGrid)))
  {
    if ((NVEC(theGrid)>0) || (NC(theGrid)>0))
    {
      errors++;
      UserWriteF("coarse grid not fixed but vectors allocated\n");
    }
    return(errors);
  }

  s2p = BVPD_S2P_PTR(MG_BVPD(MYMG(theGrid)));
  fmt = MGFORMAT(MYMG(theGrid));

  /* reset USED flag */
  for (theVector=PFIRSTVECTOR(theGrid); theVector!=NULL;
       theVector=SUCCVC(theVector))
  {
    SETVCUSED(theVector,0);
  }

  /* check pointers to element, side, edge vector */
  for (theElement=PFIRSTELEMENT(theGrid); theElement!=NULL;
       theElement=SUCCE(theElement))
  {

    /* check element vectors */
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,ELEMVEC))
    {
      theVector = EVECTOR(theElement);
      errors += CheckVector(fmt,s2p,(GEOM_OBJECT *) theElement, "ELEMENT",
                            theVector, ELEMVEC,NOSIDE);
    }

                #ifdef __THREEDIM__
    /* check side vectors */
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
    {
      for (i=0; i<SIDES_OF_ELEM(theElement); i++)
      {
        theVector = SVECTOR(theElement,i);
        errors += CheckVector(fmt,s2p,(GEOM_OBJECT *) theElement, "ELEMSIDE",
                              theVector, SIDEVEC,i);
      }
    }
                #endif
  }

  for (theNode=PFIRSTNODE(theGrid); theNode!=NULL; theNode=SUCCN(theNode))
  {

    /* check node vectors */
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,NODEVEC))
    {
      theVector = NVECTOR(theNode);
      errors += CheckVector(fmt,s2p,(GEOM_OBJECT *) theNode, "NODE", theVector,
                            NODEVEC,NOSIDE);
    }

    /* check edge vectors */
    if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
    {
      for (theLink=START(theNode); theLink!=NULL; theLink=NEXT(theLink))
      {
        theEdge = GetEdge(theNode,NBNODE(theLink));
        if (theEdge != NULL) {
          theVector = EDVECTOR(theEdge);
          errors += CheckVector(fmt,s2p,(GEOM_OBJECT *) theEdge, "EDGE",
                                theVector, EDGEVEC,NOSIDE);
        }
      }
    }
  }

  /* check USED flag */
  for (theVector=PFIRSTVECTOR(theGrid); theVector!=NULL;
       theVector=SUCCVC(theVector))
  {
    if (VCUSED(theVector) != 1)
    {
      errors++;
      UserWriteF("vector" VINDEX_FMTX " NOT referenced by an geom_object: "
                 "vtype=%d, objptr=%x",
                 VINDEX_PRTX(theVector), VTYPE(theVector), VOBJECT(theVector));
      if (VOBJECT(theVector) != NULL)
        UserWriteF(" objtype=%d\n",OBJT(VOBJECT(theVector)));
      else
        UserWrite("\n");
    }
    else
      SETVCUSED(theVector,0);
  }

  /* check validity of all defined connections */
  errors += CheckConnections(theGrid);

  /* reset flags in connections */
  for (theVector=PFIRSTVECTOR(theGrid); theVector!=NULL;
       theVector=SUCCVC(theVector))
  {
    MATRIX  *theMatrix;

    for (theMatrix=VSTART(theVector); theMatrix!=NULL;
         theMatrix = MNEXT(theMatrix)) SETCUSED(MMYCON(theMatrix),0);
  }

  /* set flags in connections */
#if defined __OVERLAP2__
  for (theVector=PFIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
#else
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
#endif
  {
    MATRIX  *theMatrix;

    for (theMatrix=VSTART(theVector); theMatrix!=NULL;
         theMatrix = MNEXT(theMatrix)) SETMUSED(MADJ(theMatrix),1);
  }

  /* check matrices and connections */
  for (theVector=PFIRSTVECTOR(theGrid);
       theVector!=NULL;
       theVector=SUCCVC(theVector))
  {
    MATRIX  *theMatrix;
                #ifdef ModelP
    INT prio = PRIO(theVector);
                #endif

    for (theMatrix=VSTART(theVector);
         theMatrix!=NULL;
         theMatrix = MNEXT(theMatrix))
    {
      MATRIX *Adj = MADJ(theMatrix);

      if (MDEST(theMatrix) == NULL)
      {
        errors++;
        UserWriteF("ERROR: matrix %x has no dest, start vec="
                   VINDEX_FMTX "\n",
                   theMatrix,VINDEX_PRTX(theVector));
      }
      if (MDEST(Adj) != theVector)
      {
        errors++;
        UserWriteF("ERROR: dest=%x of adj matrix "
                   " unequal vec=" VINDEX_FMTX "\n",
                   MDEST(Adj),VINDEX_PRTX(theVector));
      }

                        #if defined ModelP && ! defined  __OVERLAP2__
      if (prio != PrioHGhost)
                        #endif
      if (MUSED(theMatrix)!=1 &&  !CEXTRA(MMYCON(theMatrix)))
      {
        errors++;
        UserWriteF("ERROR: connection dead vec=" VINDEX_FMTX
                   " vector=" VINDEX_FMTX " con=%x mat=%x matadj=%x level(vec)=%d is_extra_con %d\n",
                   VINDEX_PRTX(theVector),VINDEX_PRTX(MDEST(theMatrix)),
                   MMYCON(theMatrix),MDEST(theMatrix),MDEST(MADJ(theMatrix)),
                   GLEVEL(theGrid),CEXTRA(MMYCON(theMatrix)));
      }

                        #if defined ModelP && ! defined  __OVERLAP2__
      if (GHOSTPRIO(prio) && !CEXTRA(MMYCON(theMatrix)))
      {
        errors++;
        UserWriteF("ERROR: ghost vector has matrix vec="
                   VINDEX_FMTX " con=%x mat=%x\n",
                   VINDEX_PRTX(theVector),MMYCON(theMatrix),theMatrix);
      }
                        #endif
    }
  }

  return(errors);
}

/****************************************************************************/
/** \brief Decide whether a vector corresponds to an element or not

 * @param theElement - pointer to element
 * @param theVector - pointer to a vector

   This function decides whether a given vector belongs to the given element, or
   one of its sides, edges or nodes.

 * @return <ul>
 *   <li>   0 if does not correspond </li>
 *   <li>   1 if does correspond.	 </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX VectorInElement (ELEMENT *theElement, VECTOR *theVector)
{
  INT i;
  VECTOR *vList[20];
  INT cnt;

  if (VOTYPE(theVector) == ELEMVEC)
  {
    GetVectorsOfElement(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
      if (vList[i]==theVector) RETURN(1);
  }
        #ifdef __THREEDIM__
  if (VOTYPE(theVector) == SIDEVEC)
  {
    GetVectorsOfSides(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
      if (vList[i]==theVector) RETURN(1);
  }
    #endif
  if (VOTYPE(theVector) == EDGEVEC)
  {
    GetVectorsOfEdges(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
      if (vList[i]==theVector) RETURN(1);
  }
  if (VOTYPE(theVector) == NODEVEC)
  {
    GetVectorsOfNodes(theElement,&cnt,vList);
    for (i=0; i<cnt; i++)
      if (vList[i]==theVector) RETURN(1);
  }

  return (0);
}

/****************************************************************************/
/** \brief Calc coordinate position of vector

 * @param theVector - a given vector
 * @param position - array to be filled

   This function calcs physical position of vector. For edge vectors the
   midpoint is returned, and for sides and elements the center of mass.

 * @return <ul>
 *   <li>    0 if ok                     </li>
 *   <li>    1 if error occured.	 </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX VectorPosition (const VECTOR *theVector, DOUBLE *position)
{
  INT i;
  EDGE *theEdge;
        #ifdef __THREEDIM__
  ELEMENT *theElement;
  INT theSide,j;
        #endif

  ASSERT(theVector != NULL);

        #if defined __OVERLAP2__
  if( VOBJECT(theVector) == NULL )
  {
    for (i=0; i<DIM; i++)
      position[i] = -MAX_D;
    return (0);
  }
        #endif

  switch (VOTYPE(theVector))
  {
  case NODEVEC :
    for (i=0; i<DIM; i++)
      position[i] = CVECT(MYVERTEX((NODE*)VOBJECT(theVector)))[i];
    return (0);

  case EDGEVEC :
    theEdge = (EDGE*)VOBJECT(theVector);
    for (i=0; i<DIM; i++)
      position[i] = 0.5*(CVECT(MYVERTEX(NBNODE(LINK0(theEdge))))[i] +
                         CVECT(MYVERTEX(NBNODE(LINK1(theEdge))))[i]   );
    return (0);
                #ifdef __THREEDIM__
  case SIDEVEC :
    theElement = (ELEMENT *)VOBJECT(theVector);
    theSide = VECTORSIDE(theVector);
    for (i=0; i<DIM; i++)
    {
      position[i] = 0.0;
      for(j=0; j<CORNERS_OF_SIDE(theElement,theSide); j++)
        position[i] += CVECT(MYVERTEX(CORNER(theElement,CORNER_OF_SIDE(theElement,theSide,j))))[i];
      position[i] /= CORNERS_OF_SIDE(theElement,theSide);
    }
    return (0);
                #endif
  case ELEMVEC :
    /* calculate center of mass */
    CalculateCenterOfMass( (ELEMENT *) VOBJECT(theVector), position );
    return (0);

  default : PrintErrorMessage('E',"VectorPosition","unrecognized object type for vector");
    assert(0);
  }

  RETURN (GM_ERROR);
}


/****************************************************************************/
/** \brief Initialize vector classes

 * @param theGrid - given grid
 * @param theElement - given element

   Initialize vector class in all vectors associated with given element with 3.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX SeedVectorClasses (GRID *theGrid, ELEMENT *theElement)
{
  INT i;
  VECTOR *vList[20];
  INT cnt;

  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,ELEMVEC))
  {
    GetVectorsOfElement(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVCLASS(vList[i],3);
  }
        #ifdef __THREEDIM__
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
  {
    GetVectorsOfSides(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVCLASS(vList[i],3);
  }
    #endif
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
  {
    GetVectorsOfEdges(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVCLASS(vList[i],3);
  }
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,NODEVEC))
  {
    GetVectorsOfNodes(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVCLASS(vList[i],3);
  }
  return (0);
}

/****************************************************************************/
/** \brief Reset vector classes

 * @param theGrid - pointer to grid

   Reset all vector classes in all vectors of given grid to 0.

 * @return <ul>
 *   <li>    0 if ok </li>
 *   <li>    1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX ClearVectorClasses (GRID *theGrid)
{
  VECTOR *theVector;

  /* reset class of each vector to 0 */
  for (theVector=PFIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
    SETVCLASS(theVector,0);

  return(0);
}


#ifdef ModelP
static int Gather_VectorVClass (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  PRINTDEBUG(gm,1,("Gather_VectorVClass(): v=" VINDEX_FMTX " vclass=%d\n",
                   VINDEX_PRTX(theVector),VCLASS(theVector)))

    ((INT *)data)[0] = VCLASS(theVector);

  return(0);
}

static int Scatter_VectorVClass (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  SETVCLASS(theVector,MAX(VCLASS(theVector),((INT *)data)[0]));

  PRINTDEBUG(gm,2,("Scatter_VectorVClass(): v=" VINDEX_FMTX " vclass=%d\n",
                   VINDEX_PRTX(theVector),VCLASS(theVector)))

  return(0);
}

static int Scatter_GhostVectorVClass (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  SETVCLASS(theVector,((INT *)data)[0]);

  PRINTDEBUG(gm,1,("Scatter_GhostVectorVClass(): v=" VINDEX_FMTX " vclass=%d\n",
                   VINDEX_PRTX(theVector),VCLASS(theVector)))

  return(0);
}
#endif

static INT PropagateVectorClass (GRID *theGrid, INT vclass)
{
  VECTOR *theVector;
  MATRIX *theMatrix;

  /* set vector classes in the algebraic neighborhood to vclass-1 */
  /* use matrices to determine next vectors!!!!!                   */
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL;
       theVector=SUCCVC(theVector))
    if ((VCLASS(theVector)==vclass)&&(VSTART(theVector)!=NULL))
      for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL;
           theMatrix=MNEXT(theMatrix))
        if ((VCLASS(MDEST(theMatrix))<vclass)
            &&(CEXTRA(MMYCON(theMatrix))!=1))
          SETVCLASS(MDEST(theMatrix),vclass-1);

  /* only for this values valid */
  ASSERT(vclass==3 || vclass==2);

  return(0);
}
#ifdef __PERIODIC_BOUNDARY__
static INT PropagatePeriodicVectorClass (GRID *theGrid, INT vclass)
{
  VECTOR *theVector;
  MATRIX *theMatrix;

  /* set vector classes in the algebraic neighborhood to vclass-1 */
  /* use matrices to determine next vectors!!!!!                   */
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
    if ((VCLASS(theVector)==vclass)&&(VSTART(theVector)!=NULL))
      for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL;
           theMatrix=MNEXT(theMatrix))
        if ((VCLASS(MDEST(theMatrix))<vclass)
            &&(CEXTRA(MMYCON(theMatrix))!=1)) {
          SETVCLASS(MDEST(theMatrix),vclass);
        }

  /* only for this value valid */
  ASSERT(vclass==1);

  return(0);
}
#endif


/****************************************************************************/
/** \brief Compute vector classes after initialization

 * @param theGrid - pointer to grid

   After vector classes have been reset and initialized, this function
   now computes the class 2 and class 1 vectors.

 * @return <ul>
 *   <li>     0 if ok </li>
 *   <li>     1 if error occured	 </li>
   </ul>
 */
/****************************************************************************/
INT NS_DIM_PREFIX PropagateVectorClasses (GRID *theGrid)
{
    #ifdef ModelP
  auto& context = theGrid->dddContext();
  const auto& dddctrl = ddd_ctrl(context);

  PRINTDEBUG(gm,1,("\nPropagateVectorClasses():"
                   " 1. communication on level %d\n",GLEVEL(theGrid)))
  /* exchange VCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVClass, Scatter_VectorVClass);
    #endif

  /* set vector classes in the algebraic neighborhood to 2 */
  if (PropagateVectorClass(theGrid,3)) REP_ERR_RETURN(1);

    #ifdef ModelP
  PRINTDEBUG(gm,1,("\nPropagateVectorClasses(): 2. communication\n"))
  /* exchange VCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVClass, Scatter_VectorVClass);
    #endif

  /* set vector classes in the algebraic neighborhood to 1 */
  if (PropagateVectorClass(theGrid,2)) REP_ERR_RETURN(1);

    #ifdef ModelP
  PRINTDEBUG(gm,1,("\nPropagateVectorClasses(): 3. communication\n"))
  /* exchange VCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVClass, Scatter_VectorVClass);
    #endif

#ifdef __PERIODIC_BOUNDARY__
  /* set vector classes in the periodic neighbourhood to 1 */
  if (PropagatePeriodicVectorClass(theGrid,1)) REP_ERR_RETURN(1);

    #ifdef ModelP
  PRINTDEBUG(gm,1,("\nPropagateVectorClasses(): 4. communication\n"))
  /* exchange VCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVClass, Scatter_VectorVClass);
        #endif
#endif

        #ifdef ModelP
  /* send VCLASS to ghosts */
  DDD_IFAOneway(context,
                dddctrl.VectorIF,GRID_ATTR(theGrid),IF_FORWARD,sizeof(INT),
                Gather_VectorVClass, Scatter_GhostVectorVClass);
    #endif

  return(0);
}

/****************************************************************************/
/** \brief Reset class of the vectors on the next level

 * @param theGrid - pointer to grid

   This function clears VNCLASS flag in all vectors. This is the first step to
   compute the class of the dofs on the *NEXT* level, which
   is also the basis for determining copies.

 * @return <ul>
 *   <li>    0 if ok </li>
 *   <li>    1 if error occured.			 </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX ClearNextVectorClasses (GRID *theGrid)
{
  VECTOR *theVector;

  /* reset class of each vector to 0 */
  for (theVector=PFIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
    SETVNCLASS(theVector,0);

  /* now the refinement algorithm will initialize the class 3 vectors */
  /* on the *NEXT* level.                                                                                       */
  return(0);
}

/****************************************************************************/
/** \brief Set VNCLASS in all vectors associated with element

 * @param theGrid - given grid
 * @param theElement - pointer to element

   Set VNCLASS in all vectors associated with the element to 3.

 * @return <ul>
 *   <li>    0 if ok  </li>
 *   <li>    1 if error occured.	 </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX SeedNextVectorClasses (GRID *theGrid, ELEMENT *theElement)
{
  INT i;
  VECTOR *vList[20];
  INT cnt;

  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,ELEMVEC))
  {
    GetVectorsOfElement(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVNCLASS(vList[i],3);
  }
        #ifdef __THREEDIM__
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
  {
    GetVectorsOfSides(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVNCLASS(vList[i],3);
  }
        #endif
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
  {
    GetVectorsOfEdges(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVNCLASS(vList[i],3);
  }
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,NODEVEC))
  {
    GetVectorsOfNodes(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) SETVNCLASS(vList[i],3);
  }
  return (0);
}




#ifdef ModelP
static int Gather_VectorVNClass (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  PRINTDEBUG(gm,2,("Gather_VectorVNClass(): v=" VINDEX_FMTX " vnclass=%d\n",
                   VINDEX_PRTX(theVector),VNCLASS(theVector)))

    ((INT *)data)[0] = VNCLASS(theVector);

  return(GM_OK);
}

static int Scatter_VectorVNClass (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  SETVNCLASS(theVector,MAX(VNCLASS(theVector),((INT *)data)[0]));

  PRINTDEBUG(gm,2,("Scatter_VectorVNClass(): v=" VINDEX_FMTX " vnclass=%d\n",
                   VINDEX_PRTX(theVector),VNCLASS(theVector)))

  return(GM_OK);
}

static int Scatter_GhostVectorVNClass (DDD::DDDContext&, DDD_OBJ obj, void *data)
{
  VECTOR *theVector = (VECTOR *)obj;

  SETVNCLASS(theVector,((INT *)data)[0]);

  PRINTDEBUG(gm,2,("Scatter_GhostVectorVNClass(): v=" VINDEX_FMTX " vnclass=%d\n",
                   VINDEX_PRTX(theVector),VNCLASS(theVector)))

  return(GM_OK);
}
#endif

static INT PropagateNextVectorClass (GRID *theGrid, INT vnclass)
{
  VECTOR *theVector;
  MATRIX *theMatrix;

  /* set vector classes in the algebraic neighborhood to vnclass-1 */
  /* use matrices to determine next vectors!!!!!                   */
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL;
       theVector=SUCCVC(theVector))
    if ((VNCLASS(theVector)==vnclass)&&(VSTART(theVector)!=NULL))
      for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL;
           theMatrix=MNEXT(theMatrix))
        if ((VNCLASS(MDEST(theMatrix))<vnclass)
            &&(CEXTRA(MMYCON(theMatrix))!=1))
          SETVNCLASS(MDEST(theMatrix),vnclass-1);

  /* only for this values valid */
  ASSERT(vnclass==3 || vnclass==2);

  return(0);
}

#ifdef __PERIODIC_BOUNDARY__
static INT PropagatePeriodicNextVectorClass (GRID *theGrid)
{
  VECTOR *theVector;
  MATRIX *theMatrix;

  /* set vector classes in the periodic neighborhood to 1 */
  /* use matrices to determine next vectors!!!!!                   */
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL;
       theVector=SUCCVC(theVector))
    if ((VNCLASS(theVector)==1)&&(VSTART(theVector)!=NULL))
      for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL;
           theMatrix=MNEXT(theMatrix))
        if ((VNCLASS(MDEST(theMatrix))<1)
            &&(CEXTRA(MMYCON(theMatrix))!=1)) {
          SETVNCLASS(MDEST(theMatrix),1);
          PRINTDEBUG(gm,1,("VNCLASS(%d)=1\n",VINDEX(MDEST(theMatrix))));
        }

  return(0);
}
#endif

/****************************************************************************/
/** \brief Compute VNCLASS in all vectors of a grid level

 * @param theGrid - pointer to grid

   Computes values of VNCLASS field in all vectors after seed.

 * @return <ul>
 *   <li>   0 if ok              </li>
 *   <li>   1 if error occured </li>
   </ul>
 */
/****************************************************************************/
INT NS_DIM_PREFIX PropagateNextVectorClasses (GRID *theGrid)
{
    #ifdef ModelP
  auto& context = theGrid->dddContext();
  const auto& dddctrl = ddd_ctrl(context);

  PRINTDEBUG(gm,1,("\nPropagateNextVectorClasses(): 1. communication\n"))
  /* exchange VNCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVNClass, Scatter_VectorVNClass);
    #endif

  if (PropagateNextVectorClass(theGrid,3)) REP_ERR_RETURN(1);

    #ifdef ModelP
  PRINTDEBUG(gm,1,("\nPropagateNextVectorClasses(): 2. communication\n"))
  /* exchange VNCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVNClass, Scatter_VectorVNClass);
    #endif

  if (PropagateNextVectorClass(theGrid,2)) REP_ERR_RETURN(1);

    #ifdef ModelP
  PRINTDEBUG(gm,1,("\nPropagateNextVectorClasses(): 3. communication\n"))
  /* exchange VNCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVNClass, Scatter_VectorVNClass);
        #endif

#ifdef __PERIODIC_BOUNDARY__
  if (PropagatePeriodicNextVectorClass(theGrid)) REP_ERR_RETURN(1);

    #ifdef ModelP
  PRINTDEBUG(gm,1,("\nPropagateNextVectorClasses(): 4. communication\n"))
  /* exchange VNCLASS of vectors */
  DDD_IFAExchange(context,
                  dddctrl.BorderVectorSymmIF,GRID_ATTR(theGrid),sizeof(INT),
                  Gather_VectorVNClass, Scatter_VectorVNClass);
        #endif
#endif

        #ifdef ModelP
  /* send VCLASS to ghosts */
  DDD_IFAOneway(context,
                dddctrl.VectorIF,GRID_ATTR(theGrid),IF_FORWARD,sizeof(INT),
                Gather_VectorVNClass, Scatter_GhostVectorVNClass);
    #endif

  return(0);
}

/****************************************************************************/
/** \brief Returns highest vector class of a dof on next level

 * @param theGrid - pointer to a grid
 * @param theElement - pointer to a element

   This function returns highest VNCLASS of a vector associated with the
   element.

 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
   </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX MaxNextVectorClass (GRID *theGrid, ELEMENT *theElement)
{
  INT i,m;
  VECTOR *vList[20];
  INT cnt;

  m = 0;
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,ELEMVEC))
  {
    GetVectorsOfElement(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) m = MAX(m,VNCLASS(vList[i]));
  }
        #ifdef __THREEDIM__
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,SIDEVEC))
  {
    GetVectorsOfSides(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) m = MAX(m,VNCLASS(vList[i]));
  }
        #endif
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,EDGEVEC))
  {
    GetVectorsOfEdges(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) m = MAX(m,VNCLASS(vList[i]));
  }
  if (VEC_DEF_IN_OBJ_OF_GRID(theGrid,NODEVEC))
  {
    GetVectorsOfNodes(theElement,&cnt,vList);
    for (i=0; i<cnt; i++) m = MAX(m,VNCLASS(vList[i]));
  }
  return (m);
}

/****************************************************************************/
/** \brief Create a new find cut procedure in environment

 * @param name - name
 * @param FindCutProc -  the find cut procedure

   This function creates a new find cut dependency in environement.

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

FIND_CUT * NS_DIM_PREFIX CreateFindCutProc (const char *name, FindCutProcPtr FindCutProc)
{
  FIND_CUT *newFindCut;

  if (ChangeEnvDir("/FindCut")==NULL)
  {
    UserWrite("cannot change to dir '/FindCut'\n");
    return(NULL);
  }
  newFindCut = (FIND_CUT *) MakeEnvItem (name,theFindCutVarID,sizeof(FIND_CUT));
  if (newFindCut==NULL) return(NULL);

  newFindCut->FindCutProc = FindCutProc;

  return (newFindCut);
}

/****************************************************************************/
/** \brief Create a new algebraic dependency in environment

 * @param name - name
 * @param DependencyProc -  the dependency procedure

   This function creates a new algebraic dependency in environement.

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

ALG_DEP * NS_DIM_PREFIX CreateAlgebraicDependency (const char *name, DependencyProcPtr DependencyProc)
{
  ALG_DEP *newAlgDep;

  if (ChangeEnvDir("/Alg Dep")==NULL)
  {
    UserWrite("cannot change to dir '/Alg Dep'\n");
    return(NULL);
  }
  newAlgDep = (ALG_DEP *) MakeEnvItem (name,theAlgDepVarID,sizeof(ALG_DEP));
  if (newAlgDep==NULL) return(NULL);

  newAlgDep->DependencyProc = DependencyProc;

  return (newAlgDep);
}

/****************************************************************************/
/** \brief Put `every` vector !VCUSED into the new order list

 * @param theGrid - pointer to grid
   .  CutVectors -
   .  nb -

   This function can be used as a find-cut-procedure for the streamwise ordering
   algorithm. But it just puts `all` the remaining vectors into the new order
   list instead of removing only as much as necessary to get rid of cyclic
   dependencies.

   It is used as default when no cut procedure is specified.

 * @return <ul>
 *   <li>   0 if ok
 *   <li>   1 if error occured.
   </ul>
 */
/****************************************************************************/

static VECTOR *FeedbackVertexVectors (GRID *theGrid, VECTOR *LastVector, INT *nb)
{
  VECTOR *theVector;

  /* push all remaining vectors */
  *nb = 0;
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
    if (!VCUSED(theVector))
    {
      (*nb)++;
      PREDVC(LastVector) = theVector;
      LastVector = theVector;
      SETVCUSED(theVector,1);
    }
  return (LastVector);
}


/****************************************************************************/
/** \brief Dependency function for lexicographic ordering

 * @param theGrid - pointer to grid
 * @param data - option string from orderv command

   This function defines a dependency function for lexicographic ordering.

 * @return <ul>
 *   <li>   0 if ok
 *   <li>   1 if error occured.
   </ul>
 */
/****************************************************************************/

static INT LexAlgDep (GRID *theGrid, const char *data)
{
  MULTIGRID *theMG;
  VECTOR *theVector,*NBVector;
  MATRIX *theMatrix;
  DOUBLE_VECTOR pos,nbpos;
  DOUBLE diff[DIM];
  INT i,order,res;
  INT Sign[DIM],Order[DIM],xused,yused,zused,error;
  char ord[3];

  /* read ordering directions */
        #ifdef __TWODIM__
  res = sscanf(data,expandfmt("%2[rlud]"),ord);
        #else
  res = sscanf(data,expandfmt("%3[rlbfud]"),ord);
        #endif
  if (res!=1)
  {
    PrintErrorMessage('E',"LexAlgDep","could not read order type");
    return(1);
  }
  if (strlen(ord)!=DIM)
  {
                #ifdef __TWODIM__
    PrintErrorMessage('E',"LexAlgDep","specify 2 chars out of 'rlud'");
                #else
    PrintErrorMessage('E',"LexAlgDep","specify 3 chars out of 'rlbfud'");
                #endif
    return(1);
  }
  error = xused = yused = zused = false;
  for (i=0; i<DIM; i++)
    switch (ord[i])
    {
    case 'r' :
      if (xused) error = true;
      xused = true;
      Order[i] = _X_; Sign[i] =  1; break;
    case 'l' :
      if (xused) error = true;
      xused = true;
      Order[i] = _X_; Sign[i] = -1; break;

                        #ifdef __TWODIM__
    case 'u' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] =  1; break;
    case 'd' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] = -1; break;
                        #else
    case 'b' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] =  1; break;
    case 'f' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] = -1; break;

    case 'u' :
      if (zused) error = true;
      zused = true;
      Order[i] = _Z_; Sign[i] =  1; break;
    case 'd' :
      if (zused) error = true;
      zused = true;
      Order[i] = _Z_; Sign[i] = -1; break;
                        #endif
    }
  if (error)
  {
    PrintErrorMessage('E',"LexAlgDep","bad combination of 'rludr' or 'rlbfud' resp.");
    return(1);
  }

  theMG   = MYMG(theGrid);

  /* find an approximate measure for the mesh size */
  // The following method wants the domain radius, which has been removed.
  // Dune has been setting this radius to 1.0 for years now, so I don't think it matters.
  DOUBLE BVPD_RADIUS = 1.0;
  InvMeshSize = POW2(GLEVEL(theGrid)) * pow(NN(GRID_ON_LEVEL(theMG,0)),1.0/DIM) / BVPD_RADIUS;

  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
  {
    VectorPosition(theVector,pos);

    for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL; theMatrix=MNEXT(theMatrix))
    {
      NBVector = MDEST(theMatrix);

      SETMUP(theMatrix,0);
      SETMDOWN(theMatrix,0);

      VectorPosition(NBVector,nbpos);

      V_DIM_SUBTRACT(nbpos,pos,diff);
      V_DIM_SCALE(InvMeshSize,diff);

      if (fabs(diff[Order[DIM-1]])<ORDERRES)
      {
                                      #ifdef __THREEDIM__
        if (fabs(diff[Order[DIM-2]])<ORDERRES)
        {
          if (diff[Order[DIM-3]]>0.0) order = -Sign[DIM-3];
          else order =  Sign[DIM-3];
        }
        else
                                      #endif
        if (diff[Order[DIM-2]]>0.0) order = -Sign[DIM-2];
        else order =  Sign[DIM-2];
      }
      else
      {
        if (diff[Order[DIM-1]]>0.0) order = -Sign[DIM-1];
        else order =  Sign[DIM-1];
      }
      
      if (order==1) SETMUP(theMatrix,1);
      else SETMDOWN(theMatrix,1);
    }
  }

  return (0);
}

/****************************************************************************/
/** \brief Dependency function for lexicographic ordering

 * @param theGrid - pointer to grid
 * @param data - option string from orderv command

   This function defines a dependency function for lexicographic ordering.

 * @return <ul>
 *   <li>   0 if ok
 *   <li>   1 if error occured.
   </ul>
 */
/****************************************************************************/

static INT StrongLexAlgDep (GRID *theGrid, const char *data)
{
  MULTIGRID *theMG;
  VECTOR *theVector,*NBVector;
  MATRIX *theMatrix;
  DOUBLE_VECTOR pos,nbpos;
  DOUBLE diff[DIM];
  INT i,order,res;
  INT Sign[DIM],Order[DIM],xused,yused,zused,error;
  char ord[3];

  /* read ordering directions */
        #ifdef __TWODIM__
  res = sscanf(data,expandfmt("%2[rlud]"),ord);
        #else
  res = sscanf(data,expandfmt("%3[rlbfud]"),ord);
        #endif
  if (res!=1)
  {
    PrintErrorMessage('E',"LexAlgDep","could not read order type");
    return(1);
  }
  if (strlen(ord)!=DIM)
  {
                #ifdef __TWODIM__
    PrintErrorMessage('E',"LexAlgDep","specify 2 chars out of 'rlud'");
                #else
    PrintErrorMessage('E',"LexAlgDep","specify 3 chars out of 'rlbfud'");
                #endif
    return(1);
  }
  error = xused = yused = zused = false;
  for (i=0; i<DIM; i++)
    switch (ord[i])
    {
    case 'r' :
      if (xused) error = true;
      xused = true;
      Order[i] = _X_; Sign[i] =  1; break;
    case 'l' :
      if (xused) error = true;
      xused = true;
      Order[i] = _X_; Sign[i] = -1; break;

                        #ifdef __TWODIM__
    case 'u' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] =  1; break;
    case 'd' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] = -1; break;
                        #else
    case 'b' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] =  1; break;
    case 'f' :
      if (yused) error = true;
      yused = true;
      Order[i] = _Y_; Sign[i] = -1; break;

    case 'u' :
      if (zused) error = true;
      zused = true;
      Order[i] = _Z_; Sign[i] =  1; break;
    case 'd' :
      if (zused) error = true;
      zused = true;
      Order[i] = _Z_; Sign[i] = -1; break;
                        #endif
    }
  if (error)
  {
    PrintErrorMessage('E',"LexAlgDep","bad combination of 'rludr' or 'rlbfud' resp.");
    return(1);
  }

  theMG   = MYMG(theGrid);

  /* find an approximate measure for the mesh size */
  InvMeshSize = POW2(GLEVEL(theGrid)) * pow(NN(GRID_ON_LEVEL(theMG,0)),1.0/DIM);

  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
  {
    VectorPosition(theVector,pos);

    for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL; theMatrix=MNEXT(theMatrix))
    {
      NBVector = MDEST(theMatrix);

      SETMUP(theMatrix,0);
      SETMDOWN(theMatrix,0);
      SETMUSED(theMatrix,0);

      VectorPosition(NBVector,nbpos);

      V_DIM_SUBTRACT(nbpos,pos,diff);
      V_DIM_SCALE(InvMeshSize,diff);

      if (fabs(diff[Order[DIM-1]])<ORDERRES)
      {
                                #ifdef __THREEDIM__
        if (fabs(diff[Order[DIM-2]])<ORDERRES)
        {
          if (diff[Order[DIM-3]]>0.0) order = -Sign[DIM-3];
          else order =  Sign[DIM-3];
        }
        else
                                #endif
        if (diff[Order[DIM-2]]>0.0) order = -Sign[DIM-2];
        else order =  Sign[DIM-2];
        SETMUSED(theMatrix,1);
      }
      else
      {
        if (diff[Order[DIM-1]]>0.0) order = -Sign[DIM-1];
        else order =  Sign[DIM-1];
      }
      switch (order)
      {
      case  1 : SETMUP(theMatrix,1); break;
      case -1 : SETMDOWN(theMatrix,1); break;
      case  0 : SETMUP(theMatrix,1); SETMDOWN(theMatrix,1); break;
      }
    }
  }
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
  {
    SETVCUSED(theVector,0);
    SETVCFLAG(theVector,0);

    for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL; theMatrix=MNEXT(theMatrix))
      if (MUP(theMatrix) && !MUSED(theMatrix))
        break;
    if (theMatrix==NULL)
      SETVCUSED(theVector,1);
  }
  for (theVector=FIRSTVECTOR(theGrid); theVector!=NULL; theVector=SUCCVC(theVector))
    for (theMatrix=MNEXT(VSTART(theVector)); theMatrix!=NULL; theMatrix=MNEXT(theMatrix))
      if (MUSED(theMatrix) && MUSED(MADJ(theMatrix)))
      {
        SETMUP(theMatrix,1);
        SETMDOWN(theMatrix,1);
      }

  return (0);
}

/****************************************************************************/
/** \brief Init algebra
 *
 * This function inits algebra.
 *
 * @return <ul>
 *   <li>   0 if ok </li>
 *   <li>   1 if error occured. </li>
 * </ul>
 */
/****************************************************************************/

INT NS_DIM_PREFIX InitAlgebra (void)
{
  INT i;

  /* install the /Alg Dep directory */
  if (ChangeEnvDir("/")==NULL)
  {
    PrintErrorMessage('F',"InitAlgebra","could not changedir to root");
    return(__LINE__);
  }
  theAlgDepDirID = GetNewEnvDirID();
  if (MakeEnvItem("Alg Dep",theAlgDepDirID,sizeof(ENVDIR))==NULL)
  {
    PrintErrorMessage('F',"InitAlgebra","could not install '/Alg Dep' dir");
    return(__LINE__);
  }
  theAlgDepVarID = GetNewEnvVarID();

  /* install the /FindCut directory */
  if (ChangeEnvDir("/")==NULL)
  {
    PrintErrorMessage('F',"InitAlgebra","could not changedir to root");
    return(__LINE__);
  }
  theFindCutDirID = GetNewEnvDirID();
  if (MakeEnvItem("FindCut",theFindCutDirID,sizeof(ENVDIR))==NULL)
  {
    PrintErrorMessage('F',"InitAlgebra","could not install '/FindCut' dir");
    return(__LINE__);
  }
  theFindCutVarID = GetNewEnvVarID();

  /* init standard algebraic dependencies */
  if (CreateAlgebraicDependency ("lex",LexAlgDep)==NULL) return(__LINE__);
  if (CreateAlgebraicDependency ("stronglex",StrongLexAlgDep)==NULL) return(__LINE__);

  /* init default find cut proc */
  if (CreateFindCutProc ("lex",FeedbackVertexVectors)==NULL) return(__LINE__);

  for (i=0; i<MAXVOBJECTS; i++)
    switch (i)
    {
    case NODEVEC : ObjTypeName[i] = "nd"; break;
    case EDGEVEC : ObjTypeName[i] = "ed"; break;
    case ELEMVEC : ObjTypeName[i] = "el"; break;
    case SIDEVEC : ObjTypeName[i] = "si"; break;
    default : ObjTypeName[i] = "";
    }

  return (0);
}


/*@}*/
