multiGridLattice2D.hh

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/* This file is part of the Palabos library.
 *
 * Copyright (C) 2011 FlowKit Sarl
 * Avenue de Chailly 23
 * 1012 Lausanne, Switzerland
 * E-mail contact: contact@flowkit.com
 *
 * The most recent release of Palabos can be downloaded at 
 * <http://www.palabos.org/>
 *
 * The library Palabos is free software: you can redistribute it and/or
 * modify it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * The library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/* Main author: Daniel Lagrava
 **/

#ifndef MULTI_GRID_LATTICE_2D_HH
#define MULTI_GRID_LATTICE_2D_HH

#include "multiGrid/multiGridLattice2D.h"
#include "multiGrid/multiGridParameterManager.h"

#include "io/parallelIO.h"
#include "core/util.h"

namespace plb {

/* ****** MultiGridLattice2D ****** */

template <typename T, template <typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>::MultiGridLattice2D( MultiGridManagement2D management,
                        Dynamics<T,Descriptor>* backgroundDynamics,
                        plint behaviorLevel,
                        FineGridInterfaceInstantiator<T,Descriptor> *fineGridInstantiator_,
                        CoarseGridInterfaceInstantiator<T,Descriptor> *coarseGridInstantiator_  )
       : MultiGrid2D (
             management,
             behaviorLevel ), fineGridInstantiator(fineGridInstantiator_),
             coarseGridInstantiator(coarseGridInstantiator_)
{
    std::vector<Dynamics<T,Descriptor>*> dynamicsVector(this->getNumLevels());
    for (plint iLevel=0; iLevel<this->getNumLevels(); ++iLevel){
        Dynamics<T,Descriptor>* cloned = backgroundDynamics->clone();
        cloned->rescale(behaviorLevel-iLevel,behaviorLevel-iLevel);
        dynamicsVector[iLevel] = cloned;
    }
    delete backgroundDynamics;
    // generate the lattices that correspond to the blocks contained inside the management object
    lattices = generateLattices( this->getMultiGridManagement(), dynamicsVector,
                                 defaultMultiGridPolicy2D().getBlockCommunicator<T>(management.getNumLevels()),
                                 defaultMultiGridPolicy2D().getCombinedStatistics(management.getNumLevels()),
                                 fineGridInstantiator->getEnvelopeWidth());
                                 
    // initialize the internalStatSubscription (multiGrid) once all the lattices have been created
    this->internalStatSubscription().initialize();
}

template <typename T, template <typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>::MultiGridLattice2D (
        MultiGridManagement2D management,
        std::vector<BlockCommunicator2D*> communicators_,
        std::vector<CombinedStatistics*> combinedStatistics_, 
        Dynamics<T,Descriptor>* backgroundDynamics,
        plint behaviorLevel,
        FineGridInterfaceInstantiator<T,Descriptor> *fineGridInstantiator_,
        CoarseGridInterfaceInstantiator<T,Descriptor> *coarseGridInstantiator_ )
    : MultiGrid2D( management,
                   behaviorLevel ), fineGridInstantiator(fineGridInstantiator_),
      coarseGridInstantiator(coarseGridInstantiator_)
{
    std::vector<Dynamics<T,Descriptor>*> dynamicsVector(this->getNumLevels());
    for (plint iLevel=0; iLevel<this->getNumLevels(); ++iLevel){
        Dynamics<T,Descriptor>* cloned = backgroundDynamics->clone();
        cloned->rescale(behaviorLevel-iLevel,behaviorLevel-iLevel);
        dynamicsVector[iLevel] = cloned;
    }
    delete backgroundDynamics;
    // generate the lattices that correspond to the blocks contained inside the management object
    lattices = generateLattices( this->getMultiGridManagement(), dynamicsVector,
                                 communicators_, combinedStatistics_,
                                 fineGridInstantiator->getEnvelopeWidth() );
    // initialize the internalStatSubscription (multiGrid) once all the lattices have been created
    this->internalStatSubscription().initialize();
}


template <typename T, template <typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>::~MultiGridLattice2D(){
    for (plint i = 0; i < this->getNumLevels(); ++i){
        delete lattices[i];
        // the dynamics are taken care by each lattice
    }
    
    delete fineGridInstantiator;
    delete coarseGridInstantiator;
}

//BUG: there is a problem with the copy constructor
template <typename T, template <typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>::MultiGridLattice2D(MultiGridLattice2D<T,Descriptor> const& rhs)
  : MultiGrid2D(rhs), fineGridInstantiator(rhs.fineGridInstantiator->clone()),
    coarseGridInstantiator(rhs.coarseGridInstantiator->clone())
{
    std::vector<Dynamics<T,Descriptor>*> dynamicsVector(this->getNumLevels());
    
    for (plint iLevel=0; iLevel<this->getNumLevels(); ++iLevel){
        Dynamics<T,Descriptor>* cloned = rhs.lattices[iLevel]->getBackgroundDynamics().clone();
        dynamicsVector[iLevel] = cloned;
    }
    MultiGridManagement2D const& management = this->getMultiGridManagement();
    // generate the lattices that correspond to the blocks contained inside the management object
    lattices = generateLattices( management, dynamicsVector,
                                 defaultMultiGridPolicy2D().getBlockCommunicator<T>(management.getNumLevels()),
                                 defaultMultiGridPolicy2D().getCombinedStatistics(management.getNumLevels()),
                                 fineGridInstantiator->getEnvelopeWidth() );
                                 
    // initialize the internalStatSubscription (multiGrid) once all the lattices have been created
    this->internalStatSubscription().initialize();
}


template <typename T, template <typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>::MultiGridLattice2D( MultiGridLattice2D<T,Descriptor> const& rhs, 
                                                      Box2D subDomain, bool crop )
  : MultiGrid2D(rhs, subDomain, crop), fineGridInstantiator(rhs.fineGridInstantiator),
    coarseGridInstantiator(rhs.coarseGridInstantiator)
{
    std::vector<Dynamics<T,Descriptor>*> backgroundDynamics;
    for (plint iDyn=0; iDyn<this->getNumLevels(); ++iDyn) {
      backgroundDynamics[iDyn] = new NoDynamics<T,Descriptor>();
    }
    // generate the lattices that correspond to the blocks contained inside the management object
    lattices = generateLattices( this->getMultiGridManagement(), backgroundDynamics,
                                 this->getCommunicators(), this->getCombinedStatistics(),
                                 fineGridInstantiator->getEnvelopeWidth() );
                                 
    // initialize the internalStatSubscription (multiGrid) once all the lattices have been created
    this->internalStatSubscription().initialize();
}


template <typename T, template <typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>::MultiGridLattice2D(MultiGrid2D const& rhs)
  : MultiGrid2D(rhs)
{
    std::vector<Dynamics<T,Descriptor>*> backgroundDynamics;
    for (plint iDyn=0; iDyn<this->getNumLevels(); ++iDyn) {
      backgroundDynamics[iDyn] = new NoDynamics<T,Descriptor>();
    }
    // generate the lattices that correspond to the blocks contained inside the management object
    lattices = generateLattices( this->getMultiGridManagement(), backgroundDynamics,
                                 this->getCommunicators(), this->getCombinedStatistics() );
                                 
    // initialize the internalStatSubscription (multiGrid) once all the lattices have been created
    this->internalStatSubscription().initialize();

}

template <typename T, template <typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>::MultiGridLattice2D( MultiGrid2D const& rhs, 
                                                      Box2D subDomain, bool crop )
  : MultiGrid2D(rhs, subDomain, crop)
{
    std::vector<Dynamics<T,Descriptor>*> backgroundDynamics;
    for (plint iDyn=0; iDyn<this->getNumLevels(); ++iDyn) {
      backgroundDynamics[iDyn] = new NoDynamics<T,Descriptor>();
    }
    // generate the lattices that correspond to the blocks contained inside the management object
    lattices = generateLattices( this->getMultiGridManagement(), backgroundDynamics,
                                 this->getCommunicators(), this->getCombinedStatistics() );
                                 
    // initialize the internalStatSubscription (multiGrid) once all the lattices have been created
    this->internalStatSubscription().initialize();

}

template<typename T, template<typename U> class Descriptor>
MultiGridLattice2D<T,Descriptor>& MultiGridLattice2D<T,Descriptor>::operator= (
        MultiGridLattice2D<T,Descriptor> const& rhs )
{
    MultiGridLattice2D<T,Descriptor> tmp(rhs);
    swap(tmp);
    return *this;
}


template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::initialize()
{
    this->createInterfaces();
    
    // eliminate the statistics in the refinement overlap
    this->eliminateStatisticsInOverlap();
    
    // Execute this data processor once, because this allocates memory on the fine grid dynamcis
    //   for time t0 (after we have values for t1)
    lattices[0]->initialize();
    std::vector<std::vector<Box2D> > fineGridInterfaces = this->getMultiGridManagement().getFineInterface();
    plint timeForImmediateExecution = 0;
    plint numTimeSteps=2;
    // fineGrid interfaces start at level 1
    for (pluint iLevel=1; iLevel<fineGridInterfaces.size(); ++iLevel){
        std::vector<Box2D> levelInterfaces=fineGridInterfaces[iLevel];
        for (pluint iInterf=0; iInterf<levelInterfaces.size(); ++iInterf){
            applyProcessingFunctional (
                new Copy_t1_to_t0_2D<T, Descriptor>(numTimeSteps, timeForImmediateExecution),
                levelInterfaces[iInterf].multiply(2),
                *lattices[iLevel] );
        }
        lattices[iLevel]->initialize();
    }
    
    // toggle all stats on
    for (int iLevel = 0; iLevel < (plint)lattices.size(); ++iLevel){
        lattices[iLevel]->toggleInternalStatistics(true);
    }
    
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::createInterfaces(){
    MultiGridManagement2D management = this->getMultiGridManagement();
    
    std::vector<std::vector<Box2D> > fineGridInterfaces   = management.getFineInterface();
    std::vector<std::vector<Box2D> > coarseGridInterfaces = management.getCoarseInterface();
    std::vector<std::vector<Array<plint,2> > > coarseOrientations = management.getCoarseOrientation();
    std::vector<std::vector<Array<plint,2> > > fineOrientations   = management.getFineOrientation();

    // Create the part of the coupling in which a lattice acts as a coarse lattice.
    for (pluint iCoarse=0; iCoarse<lattices.size()-1; ++iCoarse) {
        for (pluint iInterface=0; iInterface<coarseGridInterfaces[iCoarse].size(); ++iInterface) {
            plint direction = (coarseOrientations[iCoarse][iInterface])[0]; // w.r.t. the coarse grid
            plint orientation = (coarseOrientations[iCoarse][iInterface])[1]; // w.r.t. the coarse grid
            coarseGridInstantiator->instantiateDataProcessors(coarseGridInterfaces[iCoarse][iInterface],
                                                            *lattices[iCoarse],*lattices[iCoarse+1],
                                                            direction, orientation);
        }
    }
    // Create the part of the coupling in which a lattice acts as a fine lattice.
    for (pluint iFine=1; iFine<lattices.size(); ++iFine) {
        for (pluint iInterface=0; iInterface<fineGridInterfaces[iFine].size(); ++iInterface) {
            plint direction = (fineOrientations[iFine][iInterface])[0]; // w.r.t. the fine grid
            plint orientation = (fineOrientations[iFine][iInterface])[1]; // w.r.t. the fine grid
            fineGridInstantiator->instantiateDataProcessors(fineGridInterfaces[iFine][iInterface],
                                                            *lattices[iFine-1],*lattices[iFine],
                                                            direction, orientation);
        }
    }
}

/* *** MultiGrid2D methods *** */
template <typename T, template <typename U> class Descriptor>
MultiBlockLattice2D<T,Descriptor>& MultiGridLattice2D<T,Descriptor>::getComponent(plint iBlock)
{
    PLB_PRECONDITION( iBlock >= 0 && iBlock < (plint) lattices.size() );
    return *lattices[iBlock];
}

template <typename T, template <typename U> class Descriptor>
const MultiBlockLattice2D<T,Descriptor>& MultiGridLattice2D<T,Descriptor>::getComponent(plint iBlock) const
{
    PLB_PRECONDITION( iBlock >= 0 && iBlock < (plint) lattices.size() );
    return *lattices[iBlock];
}

/* **** BlockLatticeBase2D methods **** */

template <typename T, template <typename U> class Descriptor>
Cell<T,Descriptor>& MultiGridLattice2D<T,Descriptor>::get(plint iX, plint iY){
    return lattices[this->getBehaviorLevel()]->get(iX,iY);
}

template <typename T, template <typename U> class Descriptor>
Cell<T,Descriptor> const& MultiGridLattice2D<T,Descriptor>::get(plint iX, plint iY) const{
    return lattices[this->getBehaviorLevel()]->get(iX,iY);
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::specifyStatisticsStatus(Box2D domain, bool status){
    for (plint iLevel = 0; iLevel < (plint)lattices.size(); ++iLevel){
        Box2D rescaledDomain = this->getScaleManager().scaleBox(domain,iLevel);
        lattices[iLevel]->specifyStatisticsStatus(rescaledDomain,status);
    }
}


template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::collide(Box2D domain){
    plint levelNumber = (plint)lattices.size();
    PLB_PRECONDITION( levelNumber >= 0 && levelNumber <= (plint)lattices.size() );
    for (plint iLevel = 0; iLevel < levelNumber; ++iLevel){
        // each level will iterate 2 times the iterations of level - 1
        plint fineGridIt = util::roundToInt(util::twoToThePower(iLevel));
        for (plint iterations = 0; iterations < fineGridIt; ++iterations){
            lattices[iLevel]->collide(domain);
        }
    }
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::collide() {
    plint levelNumber = (plint)lattices.size();
    PLB_PRECONDITION( levelNumber >= 0 && levelNumber <= (plint)lattices.size() );
    for (plint iLevel = 0; iLevel < levelNumber; ++iLevel){
        // each level will iterate 2 times the iterations of level - 1
        plint fineGridIt = util::roundToInt(util::twoToThePower(iLevel));
        for (plint iterations = 0; iterations < fineGridIt; ++iterations){
            lattices[iLevel]->collide();
        }
    }
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::stream(Box2D domain) {
    plint levelNumber = (plint)lattices.size();
    PLB_PRECONDITION( levelNumber >= 0 && levelNumber <= (plint)lattices.size() );
    for (plint iLevel = 0; iLevel < levelNumber; ++iLevel){
        // each level will iterate 2 times the iterations of level - 1
        plint fineGridIt = util::roundToInt(util::twoToThePower(iLevel));
        for (plint iterations = 0; iterations < fineGridIt; ++iterations){
            lattices[iLevel]->stream(domain);
        }
    }
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::stream() {
    plint levelNumber = (plint)lattices.size();
    PLB_PRECONDITION( levelNumber >= 0 && levelNumber <= (plint)lattices.size() );
    for (plint iLevel = 0; iLevel < levelNumber; ++iLevel){
        // each level will iterate 2 times the iterations of level - 1
        plint fineGridIt = util::roundToInt(util::twoToThePower(iLevel));
        for (plint iterations = 0; iterations < fineGridIt; ++iterations){
                lattices[iLevel]->stream();
        }
        // update the values for parallelism
        lattices[iLevel]->getBlockCommunicator().duplicateOverlaps(*lattices[iLevel], modif::staticVariables);
    }
    
    this->evaluateStatistics();
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::collideAndStream(Box2D domain){
    plint levelNumber = (plint)lattices.size();
    PLB_PRECONDITION( levelNumber >= 0 && levelNumber <= (plint)lattices.size() );
    for (plint iLevel = 0; iLevel < levelNumber; ++iLevel){
        // each level will iterate 2 times the iterations of level - 1
        plint fineGridIt = util::roundToInt(util::twoToThePower(iLevel));
        for (plint iterations = 0; iterations < fineGridIt; ++iterations){
            lattices[iLevel]->collideAndStream(domain);
        }
    }
}


template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::iterateMultiGrid(plint level){
    PLB_PRECONDITION( level>=0 && level<(plint)lattices.size() );
    lattices[level]->collideAndStream();
    if ((pluint)level<lattices.size()-1) {
        iterateMultiGrid(level+1);
        iterateMultiGrid(level+1);
        // Overlaps must be duplicated on the coarse lattice, because the
        //   fine->coarse copy acts on bulk nodes only.
        lattices[level]->getBlockCommunicator().duplicateOverlaps(*lattices[level], modif::staticVariables);
    }
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::collideAndStream(){
    iterateMultiGrid(0);
    this->evaluateStatistics();
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::incrementTime()
{}

template <typename T, template <typename U> class Descriptor>
TimeCounter& MultiGridLattice2D<T,Descriptor>::getTimeCounter(){
    return lattices[this->getBehaviorLevel()]->getTimeCounter();
}

template <typename T, template <typename U> class Descriptor>
TimeCounter const& MultiGridLattice2D<T,Descriptor>::getTimeCounter() const{
    return lattices[this->getBehaviorLevel()]->getTimeCounter();
}

template <typename T, template <typename U> class Descriptor>
int  MultiGridLattice2D<T,Descriptor>::getBlockId () const{
    return lattices[this->getReferenceLevel()]->getStaticId();
}

template <typename T, template <typename U> class Descriptor>
void MultiGridLattice2D<T,Descriptor>::eliminateStatisticsInOverlap(){
    // the fine interface is the region inside the fine grid that overlaps with the coarse
    //   grid. It is therefore there that we need to turn off the statistics in the 
    //   coarse grid.
    std::vector<std::vector<Box2D> > fineOverlaps = this->getMultiGridManagement().getFineInterface();
    for (plint iLevel = 0; iLevel < (plint)lattices.size()-1; ++iLevel){
        for (plint iOv = 0; iOv < (plint)fineOverlaps[iLevel].size(); ++iOv){
            Box2D currentOverlap = (fineOverlaps[iLevel])[iOv];
            lattices[iLevel]->specifyStatisticsStatus(currentOverlap, false);
        }
    }
    // it is also necessary to avoid computation in the coarse interface, as the refinement 
    //   overlap is two coarse sites
    std::vector<std::vector<Box2D> > coarseOverlaps = this->getMultiGridManagement().getCoarseInterface();
    for (plint iLevel = 0; iLevel < (plint)lattices.size()-1; ++iLevel){
        for (plint iOv = 0; iOv < (plint)coarseOverlaps[iLevel].size(); ++iOv){
            Box2D currentOverlap = (coarseOverlaps[iLevel])[iOv];
            lattices[iLevel]->specifyStatisticsStatus(currentOverlap, false);
        }
    }
    
}


template <typename T, template <typename U> class Descriptor>
std::auto_ptr<MultiBlockLattice2D<T,Descriptor> > MultiGridLattice2D<T,Descriptor>::convertToLevel(plint level) const
{
    // create the resulting multiBlock
    std::auto_ptr<MultiBlockLattice2D<T,Descriptor> > result = 
        generateMultiBlockLattice<T,Descriptor>(
                                lattices[level]->getBoundingBox(),
                                lattices[level]->getBackgroundDynamics().clone(),
                                lattices[level]->getMultiBlockManagement().getEnvelopeWidth() );
                                
    // create the first lattice to start looping
    std::auto_ptr<MultiBlockLattice2D<T,Descriptor> > refined = 
        generateMultiBlockLattice<T,Descriptor>(
                                lattices[0]->getBoundingBox(),
                                lattices[0]->getBackgroundDynamics().clone(),
                                lattices[0]->getMultiBlockManagement().getEnvelopeWidth() );

    copyNonLocal<T,Descriptor>(*lattices[0],*refined, 
                               refined->getBoundingBox(), modif::staticVariables);
    
    // loop to interpolate the blocks until level-1
    for (plint iLevel=0; iLevel<(plint)level; ++iLevel){
        plint envelopeWidth = lattices[iLevel+1]->getMultiBlockManagement().getEnvelopeWidth();
        // interpolate lattice at iLevel
        std::auto_ptr<MultiBlockLattice2D<T,Descriptor> > tmp = 
            refine(*refined,-1,-1,refined->getBackgroundDynamics().clone());
        
        refined = generateMultiBlockLattice<T,Descriptor>(lattices[iLevel+1]->getBoundingBox(),
                                                    lattices[iLevel+1]->getBackgroundDynamics().clone(),
                                                    envelopeWidth );

        // copy from reshaped iLevel to result
        copyNonLocal<T,Descriptor>(*tmp, *refined, refined->getBoundingBox(),modif::staticVariables);
        // copy from iLevel+1 to result
        copyNonLocal<T,Descriptor>(*lattices[iLevel+1], *refined, refined->getBoundingBox(),modif::staticVariables);
    }
    
    // create the last lattice to start looping in the other orientation
    plint lastLevel = getNumLevels()-1;
    std::auto_ptr<MultiBlockLattice2D<T,Descriptor> > coarsened = 
        std::auto_ptr<MultiBlockLattice2D<T,Descriptor> > ( 
                    new MultiBlockLattice2D<T,Descriptor>(*lattices[lastLevel]));
                    
    defineDynamics<T,Descriptor>( *coarsened, coarsened->getBoundingBox(),
                                  lattices[lastLevel]->getBackgroundDynamics().clone() );
                                
    copyNonLocal<T,Descriptor>(*lattices[lastLevel],*coarsened,
                               coarsened->getBoundingBox(),  modif::staticVariables);
    
    // loop to decimate the blocks until level+1
    for (plint iLevel=getNumLevels()-1; iLevel>=(plint)level+1; --iLevel){
        // interpolate lattice at iLevel
        std::auto_ptr<MultiBlockLattice2D<T,Descriptor> > tmp = 
            coarsen(*coarsened,1,1, lattices[iLevel]->getBackgroundDynamics().clone() );
        
        coarsened = generateJoinMultiBlockLattice<T,Descriptor>(*tmp, *lattices[iLevel-1]);
        // make all the dynamics from refinement disappear
        defineDynamics<T,Descriptor>(*coarsened, coarsened->getBoundingBox(), 
                                     lattices[iLevel-1]->getBackgroundDynamics().clone() );
        
        // copy from reshaped iLevel to result
        copyNonLocal<T,Descriptor>(*tmp, *coarsened, coarsened->getBoundingBox(),modif::staticVariables);
        // copy from iLevel-1 to result
        copyNonLocal<T,Descriptor>(*lattices[iLevel-1], *coarsened, coarsened->getBoundingBox(),modif::staticVariables);
    }
    
    // final copies
    copyNonLocal<T,Descriptor>(*refined, *result, result->getBoundingBox(),modif::staticVariables);
    copyNonLocal<T,Descriptor>(*lattices[level], *result, result->getBoundingBox(),modif::staticVariables);
    copyNonLocal<T,Descriptor>(*coarsened, *result, result->getBoundingBox(),modif::staticVariables);
    
    return result;
}


template<typename T, template<typename U> class Descriptor>
double getStoredAverageDensity(MultiGridLattice2D<T,Descriptor> const& multiGrid){
    return Descriptor<T>::fullRho (
                 multiGrid.getInternalStatistics().getAverage(
                    LatticeStatistics::avRhoBar ) );
}

template<typename T, template<typename U> class Descriptor>
double getStoredAverageEnergy(MultiGridLattice2D<T,Descriptor> const& multiGrid){
    return 0.5 * multiGrid.getInternalStatistics().getAverage(
                                            LatticeStatistics::avUSqr );
}

template<typename T, template<typename U> class Descriptor>
double getStoredMaxVelocity(MultiGridLattice2D<T,Descriptor> const& multiGrid){
    return std::sqrt( multiGrid.getInternalStatistics().getMax (
                               LatticeStatistics::maxUSqr ) );
}


}// namespace plb

#endif  // MULTI_GRID_LATTICE_2D_HH