text: /////////////////////////////////////////////////////////////
  //                                                         //
  // Copyright (c) 2003-2017 by The University of Queensland //
  // Centre for Geoscience Computing                         //
  // http://earth.uq.edu.au/centre-geoscience-computing      //
  //                                                         //
  // Primary Business: Brisbane, Queensland, Australia       //
  // Licensed under the Open Software License version 3.0    //
  // http://www.apache.org/licenses/LICENSE-2.0              //
  //                                                         //
  /////////////////////////////////////////////////////////////
  
  
  #include "pis/pi_storage.h"
  
  //----------------------------------------------
  //       CElasticInteractionGroup functions
  //----------------------------------------------
  template<class T>
  CRotElasticInteractionGroup<T>::CRotElasticInteractionGroup()
  {
    m_exIG=NULL;
    this->m_update_timestamp=0;
  }
  
  template<class T>
  CRotElasticInteractionGroup<T>::CRotElasticInteractionGroup(const CRotElasticIGP* Param)
  {
    m_exIG=NULL;
    this->m_kr=Param->getNormalSpringConst(); 
    this->m_update_timestamp=0;
  }
  
  template<class T>
  void CRotElasticInteractionGroup<T>::setParam(const CRotElasticIGP* Param)
  {
    this->m_kr=Param->getNormalSpringConst();
  }
  
  template<class T>
  void CRotElasticInteractionGroup<T>::calcForces()
  {
  
    console.Debug() << "calculating " << m_interactions.size() << " elastic forces\n" ;
  
    for(vector<CRotElasticInteraction>::iterator it=m_interactions.begin();it!=m_interactions.end();it++){
      it->calcForces();
    }
  }
  
  /*!
    Update the interactions from the neighbor table. If the ParallelParticleArray 
    has been rebuilt since the last update, the interaction group is cleared and 
    rebuilt from scratch. Otherwise only new interactions are added.
  */
  template<class T>
  void CRotElasticInteractionGroup<T>::Update(ParallelParticleArray<T>* PPA)
  {
    console.XDebug() << "CElasticInteractionGroup::Update\n";
    int count_l=0;
  
    if(this->m_update_timestamp!=PPA->getTimeStamp()){// PPA rebuild since last update 
      // clean out old interactions
      m_interactions.erase(m_interactions.begin(),m_interactions.end());
      this->m_set.erase(this->m_set.begin(),this->m_set.end());
      // get list of pairs from PPA
      typename ParallelParticleArray<T>::PairListHandle plh=PPA->getFullPairList();
      // generate interactions from pairs
      for(typename ParallelParticleArray<T>::PairListIterator iter=plh->begin();iter!=plh->end();iter++){
        // check vs. ExIG
        vector<int> tv;
        tv.push_back(iter->first->getID());
        tv.push_back(iter->second->getID());
        if(m_exIG!=NULL){
          if(!m_exIG->isIn(tv)){
            m_interactions.push_back(CRotElasticInteraction(iter->first,iter->second,m_kr));
            this->m_set.insert(pair<int,int>(iter->first->getID(),iter->second->getID()));
            console.XDebug() << "adding pair: " << iter->first->getID() << " - " << iter->second->getID() << "\n";
            count_l++;
          } else {
            console.XDebug() << "not adding pair: " << iter->first->getID() << " - " << iter->second->getID() << "\n";
          }
        } else {
          m_interactions.push_back(CRotElasticInteraction(iter->first,iter->second,m_kr));
          this->m_set.insert(pair<int,int>(iter->first->getID(),iter->second->getID()));
          console.XDebug() << "adding pair: " << iter->first->getID() << " - " << iter->second->getID() << "\n";
        }
      }
    } else { // PPA not rebuilt since last update -> just get additional interactions
      // get list of pairs from PPA
      typename ParallelParticleArray<T>::PairListHandle plh=PPA->getNewPairList();
      for(typename ParallelParticleArray<T>::PairListIterator iter=plh->begin();iter!=plh->end();iter++){
        // check vs. ExIG
        vector<int> tv;
        tv.push_back(iter->first->getID());
        tv.push_back(iter->second->getID());
        if(m_exIG!=NULL){
          if(!m_exIG->isIn(tv)){
            m_interactions.push_back(CRotElasticInteraction(iter->first,iter->second,m_kr));
            this->m_set.insert(pair<int,int>(iter->first->getID(),iter->second->getID()));
            console.XDebug() << "adding pair: " << iter->first->getID() << " - " << iter->second->getID() << "\n";
            count_l++;
          } else {
            console.XDebug() << "not adding pair: " << iter->first->getID() << " - " << iter->second->getID() << "\n";
          }
        } else {
          m_interactions.push_back(CRotElasticInteraction(iter->first,iter->second,m_kr));
          this->m_set.insert(pair<int,int>(iter->first->getID(),iter->second->getID()));
          console.XDebug() << "adding pair: " << iter->first->getID() << " - " << iter->second->getID() << "\n";
        }
      }
    }
  
    this->m_update_timestamp=PPA->getTimeStamp();
    console.XDebug() << "added " << count_l << " pairs to EIG\n";
    console.XDebug() << "end CElasticInteractionGroup::Update\n";
  }
  
  template<class T>
  ostream& operator<<(ostream& ost,const CRotElasticInteractionGroup<T>& E)
  {
    ost << "CElasticInteractionGroup : \n";
    for(vector<CRotElasticInteraction>::const_iterator it=E.m_interactions.begin();it!=E.m_interactions.end();it++){
      ost << *it << " , " ;
    }
    ost << "exchange list: \n";
    for(set<pair<int,int> >::const_iterator vit=E.m_exchg_list.begin();vit!=E.m_exchg_list.end();vit++){
      ost << "[ " << vit->first << " from " << vit->second << " ]  ,  ";
    }
    return ost;
  }
  