BoxLibLayout.hpp

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//
// Class BoxLibLayout
//   In contrast to AMReX, OPAL is optimized for the
//   distribution of particles to cores. In AMReX the ParGDB object
//   is responsible for the particle to core distribution. This
//   layout is derived from this object and does all important
//   bunch updates. It is the interface for AMReX and Ippl.
//
//   In AMReX, the geometry, i.e. physical domain, is fixed
//   during the whole computation. Particles leaving the domain
//   would be deleted. In order to prevent this we map the particles
//   onto the domain [-1, 1]^3. Furthermore, it makes sure
//   that we have enougth grid points to represent the bunch
//   when its charges are scattered on the grid for the self-field
//   computation.
//
//   The self-field computation and the particle-to-core update
//   are performed in the particle mapped domain.
//
// Copyright (c) 2016 - 2020, Matthias Frey, Uldis Locans, Paul Scherrer Institut, Villigen PSI, Switzerland
// All rights reserved
//
// Implemented as part of the PhD thesis
// "Precise Simulations of Multibunches in High Intensity Cyclotrons"
//
// This file is part of OPAL.
//
// OPAL is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// You should have received a copy of the GNU General Public License
// along with OPAL. If not, see <https://www.gnu.org/licenses/>.
//
#ifndef BoxLibLayout_HPP
#define BoxLibLayout_HPP
 
#include "Amr/BoxLibLayout.h"
 
#include "Algorithms/Vektor.h"
#include "Message/Format.h"
#include "Message/MsgBuffer.h"
#include "Utility/PAssert.h"
#include "Utilities/OpalException.h"
 
#include <cmath>
#include <utility>
#include <vector>
 
 
template <class T, unsigned Dim>
Vector_t BoxLibLayout<T, Dim>::lowerBound = - Vector_t({1.0, 1.0, 1.0});
 
 
template <class T, unsigned Dim>
Vector_t BoxLibLayout<T, Dim>::upperBound = Vector_t({1.0, 1.0, 1.0});
 
 
template<class T, unsigned Dim>
BoxLibLayout<T, Dim>::BoxLibLayout()
    : ParticleAmrLayout<T, Dim>(),
      ParGDB(),
      refRatio_m(0)
{
    /* FIXME There might be a better solution
     *
     *
     * Figure out the number of grid points in each direction
     * such that all processes have some data at the beginning
     *
     * ( nGridPoints / maxGridSize ) ^3 = max. #procs
     *
     */
    int nProcs = Ippl::getNodes();
    int maxGridSize = 16;
 
    int nGridPoints = std::ceil( std::cbrt( nProcs ) ) * maxGridSize;
 
    this->initBaseBox_m(nGridPoints, maxGridSize);
}
 
 
template<class T, unsigned Dim>
BoxLibLayout<T, Dim>::BoxLibLayout(const BoxLibLayout* layout_p)
    : ParticleAmrLayout<T, Dim>(),
      ParGDB(layout_p->m_geom,
             layout_p->m_dmap,
             layout_p->m_ba,
             layout_p->m_rr)
{
    this->maxLevel_m = layout_p->maxLevel_m;
    refRatio_m.resize(layout_p->m_geom.size()-1);
    for (int i = 0; i < refRatio_m.size(); ++i)
        refRatio_m[i] = layout_p->refRatio(i);
}
 
 
template<class T, unsigned Dim>
BoxLibLayout<T, Dim>::BoxLibLayout(int nGridPoints, int maxGridSize)
    : ParticleAmrLayout<T, Dim>(),
      ParGDB(),
      refRatio_m(0)
{
    this->initBaseBox_m(nGridPoints, maxGridSize);
}
 
 
template<class T, unsigned Dim>
BoxLibLayout<T, Dim>::BoxLibLayout(const AmrGeometry_t &geom,
                                   const AmrProcMap_t &dmap,
                                   const AmrGrid_t &ba)
    : ParticleAmrLayout<T, Dim>(),
      ParGDB(geom, dmap, ba),
      refRatio_m(0)
{ }
 
 
template<class T, unsigned Dim>
BoxLibLayout<T, Dim>::BoxLibLayout(const AmrGeomContainer_t &geom,
                                   const AmrProcMapContainer_t &dmap,
                                   const AmrGridContainer_t &ba,
                                   const AmrIntArray_t &rr)
    : ParticleAmrLayout<T, Dim>(),
      ParGDB(geom, dmap, ba, rr),
      refRatio_m(0)
{ }
 
 
template<class T, unsigned Dim>
void BoxLibLayout<T, Dim>::setBoundingBox(double dh) {
 
    // cubic box
    int nGridPoints = this->m_geom[0].Domain().length(0);
    int maxGridSize = this->m_ba[0][0].length(0);
 
    this->initBaseBox_m(nGridPoints, maxGridSize, dh);
}
 
 
template <class T, unsigned Dim>
void BoxLibLayout<T, Dim>::setDomainRatio(const std::vector<double>& ratio) {
 
    static bool isCalled = false;
 
    if ( isCalled ) {
        return;
    }
 
    isCalled = true;
 
    if ( ratio.size() != Dim ) {
        throw OpalException("BoxLibLayout::setDomainRatio() ",
                            "Length " + std::to_string(ratio.size()) +
                            " != " + std::to_string(Dim));
    }
 
    for (unsigned int i = 0; i < Dim; ++i) {
        if ( ratio[i] <= 0.0 ) {
            throw OpalException("BoxLibLayout::setDomainRatio() ",
                                "The ratio has to be larger than zero.");
        }
 
        lowerBound[i] *= ratio[i];
        upperBound[i] *= ratio[i];
    }
}
 
 
template<class T, unsigned Dim>
void BoxLibLayout<T, Dim>::update(IpplParticleBase< BoxLibLayout<T,Dim> >& /*PData*/,
                                  const ParticleAttrib<char>* /*canSwap*/)
{
    /* Exit since we need AmrParticleBase with grids and levels for particles for this layout
     * if IpplParticleBase is used something went wrong
     */
    throw OpalException("BoxLibLayout::update(IpplParticleBase, ParticleAttrib) ",
                        "Wrong update method called.");
}
 
 
// // Function from AMReX adjusted to work with Ippl AmrParticleBase class
// // redistribute the particles using BoxLibs ParGDB class to determine where particle should go
template<class T, unsigned Dim>
void BoxLibLayout<T, Dim>::update(AmrParticleBase< BoxLibLayout<T,Dim> >& PData,
                                  int lev_min, int lev_max, bool isRegrid)
{
    // in order to avoid transforms when already done
    if ( !PData.isForbidTransform() ) {
        /* we need to update on Amr domain + boosted frame (Lorentz transform,
         * has to be undone at end of function
         */
        PData.domainMapping();
    }
 
    int nGrow = 0;
 
    unsigned N = Ippl::getNodes();
    unsigned myN = Ippl::myNode();
 
    int theEffectiveFinestLevel = this->finestLevel();
    while (!this->LevelDefined(theEffectiveFinestLevel)) {
        theEffectiveFinestLevel--;
    }
 
    if (lev_max == -1)
        lev_max = theEffectiveFinestLevel;
    else if ( lev_max > theEffectiveFinestLevel )
        lev_max = theEffectiveFinestLevel;
 
    //loop trough the particles and assign the grid and level where each particle belongs
    size_t LocalNum = PData.getLocalNum();
 
    auto& LocalNumPerLevel = PData.getLocalNumPerLevel();
 
    if ( LocalNum != LocalNumPerLevel.getLocalNumAllLevel() )
        throw OpalException("BoxLibLayout::update()",
                            "Local #particles disagrees with sum over levels");
 
    std::multimap<unsigned, unsigned> p2n; //node ID, particle
 
    std::vector<int> msgsend(N);
    std::vector<int> msgrecv(N);
 
    size_t lBegin = LocalNumPerLevel.begin(lev_min);
    size_t lEnd   = LocalNumPerLevel.end(lev_max);
 
    /* in the case of regrid we might lose a level
     * and therefore the level counter is invalidated
     */
    if ( isRegrid ) {
        lBegin = 0;
        lEnd   = LocalNum;
    }
 
 
    //loop trough particles and assign grid and level to each particle
    //if particle doesn't belong to this process save the index of the particle to be sent
    for (unsigned int ip = lBegin; ip < lEnd; ++ip) {
        // old level
        const size_t& lold = PData.Level[ip];
 
//         /*
//          * AMReX sets m_grid = -1 and m_lev = -1
//          */
//         PData.Level[ip] = -1;
//         PData.Grid[ip] = -1;
 
        //check to which level and grid the particle belongs to
        locateParticle(PData, ip, lev_min, lev_max, nGrow);
 
        // The owner of the particle is the CPU owning the finest grid
        // in state data that contains the particle.
        const size_t& lnew = PData.Level[ip];
 
        const unsigned int who = ParticleDistributionMap(lnew)[PData.Grid[ip]];
 
        --LocalNumPerLevel[lold];
 
        if (who != myN) {
            // we lost the particle to another process
            msgsend[who] = 1;
            p2n.insert(std::pair<unsigned, unsigned>(who, ip));
        } else {
            /* if we still own the particle it may have moved to
             * another level
             */
            ++LocalNumPerLevel[lnew];
        }
    }
 
    //reduce message count so every node knows how many messages to receive
    allreduce(msgsend.data(), msgrecv.data(), N, std::plus<int>());
 
    int tag = Ippl::Comm->next_tag(P_SPATIAL_TRANSFER_TAG,P_LAYOUT_CYCLE);
 
    typename std::multimap<unsigned, unsigned>::iterator i = p2n.begin();
 
    Format *format = PData.getFormat();
 
    std::vector<MPI_Request> requests;
    std::vector<MsgBuffer*> buffers;
 
    //create a message and send particles to nodes they belong to
    while (i!=p2n.end()) {
        unsigned cur_destination = i->first;
 
        MsgBuffer *msgbuf = new MsgBuffer(format, p2n.count(i->first));
 
        for (; i!=p2n.end() && i->first == cur_destination; ++i) {
            Message msg;
            PData.putMessage(msg, i->second);
            PData.destroy(1, i->second);
            msgbuf->add(&msg);
        }
 
        MPI_Request request = Ippl::Comm->raw_isend(msgbuf->getBuffer(),
                                                    msgbuf->getSize(),
                                                    cur_destination, tag);
 
        //remember request and buffer so we can delete them later
        requests.push_back(request);
        buffers.push_back(msgbuf);
 
    }
 
    //destroy the particles that are sent to other domains
    if ( LocalNum < PData.getDestroyNum() ) {
        throw OpalException("BoxLibLayout::update()",
                            "Rank " + std::to_string(myN) +
                            " can't destroy more particles than possessed.");
    } else {
        LocalNum -= PData.getDestroyNum();  // update local num
        PData.performDestroy();
    }
 
    for (int lev = lev_min; lev <= lev_max; ++lev) {
        if ( LocalNumPerLevel[lev] < 0 ) {
            throw OpalException("BoxLibLayout::update()",
                                "Negative particle level count.");
        }
    }
 
    //receive new particles
    for (int k = 0; k<msgrecv[myN]; ++k) {
        int node = Communicate::COMM_ANY_NODE;
        char *buffer = 0;
        int bufsize = Ippl::Comm->raw_probe_receive(buffer, node, tag);
        MsgBuffer recvbuf(format, buffer, bufsize);
 
        Message *msg = recvbuf.get();
        while (msg != 0) {
            /* pBeginIdx is the start index of the new particle data
             * pEndIdx is the last index of the new particle data
             */
            size_t pBeginIdx = LocalNum;
 
            LocalNum += PData.getSingleMessage(*msg);
 
            size_t pEndIdx = LocalNum;
 
            for (size_t idx = pBeginIdx; idx < pEndIdx; ++idx)
                ++LocalNumPerLevel[ PData.Level[idx] ];
 
            delete msg;
            msg = recvbuf.get();
        }
    }
 
    //wait for communication to finish and clean up buffers
    MPI_Request* requests_ptr = requests.empty()? static_cast<MPI_Request*>(0): &(requests[0]);
    MPI_Waitall(requests.size(), requests_ptr, MPI_STATUSES_IGNORE);
    for (unsigned int j = 0; j<buffers.size(); ++j) {
        delete buffers[j];
    }
 
    delete format;
 
    // there is extra work to do if there are multipple nodes, to distribute
    // the particle layout data to all nodes
    //TODO: do we need info on how many particles are on each node?
 
    //save how many total particles we have
    size_t TotalNum = 0;
    allreduce(&LocalNum, &TotalNum, 1, std::plus<size_t>());
 
    // update our particle number counts
    PData.setTotalNum(TotalNum);    // set the total atom count
    PData.setLocalNum(LocalNum);    // set the number of local atoms
 
    // final check
    if ( LocalNum != LocalNumPerLevel.getLocalNumAllLevel() )
        throw OpalException("BoxLibLayout::update()",
                            "Local #particles disagrees with sum over levels");
 
    if ( !PData.isForbidTransform() ) {
        // undo domain transformation + undo Lorentz transform
        PData.domainMapping(true);
    }
}
 
 
// Function from AMReX adjusted to work with Ippl AmrParticleBase class
//get the cell where particle is located - uses AmrParticleBase object and particle id
template <class T, unsigned Dim>
typename BoxLibLayout<T, Dim>::AmrIntVect_t
    BoxLibLayout<T, Dim>::Index(AmrParticleBase< BoxLibLayout<T,Dim> >& p,
                                const unsigned int ip,
                                int lev) const
{
    return Index(p.R[ip], lev);
}
 
//get the cell where particle is located - uses the particle position vector R
template <class T, unsigned Dim>
typename BoxLibLayout<T, Dim>::AmrIntVect_t
    BoxLibLayout<T, Dim>::Index(SingleParticlePos_t &R,
                                int lev) const
{
    AmrIntVect_t iv;
    const AmrGeometry_t& geom = Geom(lev);
 
    D_TERM(iv[0]=floor((R[0]-geom.ProbLo(0))/geom.CellSize(0));,
           iv[1]=floor((R[1]-geom.ProbLo(1))/geom.CellSize(1));,
           iv[2]=floor((R[2]-geom.ProbLo(2))/geom.CellSize(2)););
 
    iv += geom.Domain().smallEnd();
 
    return iv;
}
 
 
template <class T, unsigned Dim>
void BoxLibLayout<T, Dim>::buildLevelMask(int lev, const int ncells) {
    int covered = 0;
    int notcovered = 1;
    int physbnd = 1;
    int interior = 0;
 
    if ( lev >= (int)masks_m.size() )
        masks_m.resize(lev + 1);
 
    masks_m[lev].reset(new mask_t(ParticleBoxArray(lev),
                                  ParticleDistributionMap(lev), 1, 1));
 
    masks_m[lev]->setVal(1, 1);
 
    mask_t tmp_mask(ParticleBoxArray(lev),
                    ParticleDistributionMap(lev),
                    1, ncells);
 
    tmp_mask.setVal(0, ncells);
 
    tmp_mask.BuildMask(Geom(lev).Domain(), Geom(lev).periodicity(),
                       covered, notcovered, physbnd, interior);
 
    tmp_mask.FillBoundary(Geom(lev).periodicity());
 
    for (amrex::MFIter mfi(tmp_mask); mfi.isValid(); ++mfi) {
        const AmrBox_t& bx = mfi.validbox();
        const int* lo = bx.loVect();
        const int* hi = bx.hiVect();
 
        basefab_t& mfab = (*masks_m[lev])[mfi];
        const basefab_t& fab = tmp_mask[mfi];
 
        for (int i = lo[0]; i <= hi[0]; ++i) {
            for (int j = lo[1]; j <= hi[1]; ++j) {
                for (int k = lo[2]; k <= hi[2]; ++k) {
                    int total = 0;
 
                    for (int ii = i - ncells; ii <= i + ncells; ++ii) {
                        for (int jj = j - ncells; jj <= j + ncells; ++jj) {
                            for (int kk = k - ncells; kk <= k + ncells; ++kk) {
                                AmrIntVect_t iv(ii, jj, kk);
                                total += fab(iv);
                            }
                        }
                    }
 
                    AmrIntVect_t iv(i, j, k);
                    if (total == 0) {
                        mfab(iv) = 0;
                    }
                }
            }
        }
    }
 
    masks_m[lev]->FillBoundary(Geom(lev).periodicity());
}
 
 
template <class T, unsigned Dim>
void BoxLibLayout<T, Dim>::clearLevelMask(int lev) {
    PAssert(lev < (int)masks_m.size());
    masks_m[lev].reset(nullptr);
}
 
 
template <class T, unsigned Dim>
const std::unique_ptr<typename BoxLibLayout<T, Dim>::mask_t>&
BoxLibLayout<T, Dim>::getLevelMask(int lev) const {
    if ( lev >= (int)masks_m.size() ) {
        throw OpalException("BoxLibLayout::getLevelMask()",
                            "Unable to access level " + std::to_string(lev) + ".");
    }
    return masks_m[lev];
}
 
 
// template <class T, unsigned Dim>
// int BoxLibLayout<T, Dim>::getTileIndex(const AmrIntVect_t& iv, const Box& box, Box& tbx) {
//     if (do_tiling == false) {
//         tbx = box;
//         return 0;
//     } else {
//         //
//         // This function must be consistent with FabArrayBase::buildTileArray function!!!
//         //
//         auto tiling_1d = [](int i, int lo, int hi, int tilesize,
//                             int& ntile, int& tileidx, int& tlo, int& thi) {
//             int ncells = hi-lo+1;
//             ntile = std::max(ncells/tilesize, 1);
//             int ts_right = ncells/ntile;
//             int ts_left  = ts_right+1;
//             int nleft = ncells - ntile*ts_right;
//             int ii = i - lo;
//             int nbndry = nleft*ts_left;
//             if (ii < nbndry) {
//                 tileidx = ii / ts_left; // tiles on the left of nbndry have size of ts_left
//                 tlo = lo + tileidx * ts_left;
//                 thi = tlo + ts_left - 1;
//             } else {
//                 tileidx = nleft + (ii-nbndry) / ts_right;  // tiles on the right: ts_right
//                 tlo = lo + tileidx * ts_right + nleft;
//                 thi = tlo + ts_right - 1;
//             }
//         };
//         const AmrIntVect_t& small = box.smallEnd();
//         const AmrIntVect_t& big   = box.bigEnd();
//         AmrIntVect_t ntiles, ivIndex, tilelo, tilehi;
//
//         D_TERM(int iv0 = std::min(std::max(iv[0], small[0]), big[0]);,
//                int iv1 = std::min(std::max(iv[1], small[1]), big[1]);,
//                int iv2 = std::min(std::max(iv[2], small[2]), big[2]););
//
//         D_TERM(tiling_1d(iv0, small[0], big[0], tile_size[0], ntiles[0], ivIndex[0], tilelo[0], tilehi[0]);,
//                tiling_1d(iv1, small[1], big[1], tile_size[1], ntiles[1], ivIndex[1], tilelo[1], tilehi[1]);,
//                tiling_1d(iv2, small[2], big[2], tile_size[2], ntiles[2], ivIndex[2], tilelo[2], tilehi[2]););
//
//         tbx = Box(tilelo, tilehi);
//
//         return D_TERM(ivIndex[0], + ntiles[0]*ivIndex[1], + ntiles[0]*ntiles[1]*ivIndex[2]);
//     }
// }
 
 
//sets the grid and level where particle belongs - returns false if particle is outside the domain
template <class T, unsigned Dim>
bool BoxLibLayout<T, Dim>::Where(AmrParticleBase< BoxLibLayout<T,Dim> >& p,
                                 const unsigned int ip,
                                 int lev_min,
                                 int lev_max,
                                 int nGrow) const
{
 
    if (lev_max == -1)
        lev_max = finestLevel();
 
    PAssert(lev_max <= finestLevel());
 
    PAssert(nGrow == 0 || (nGrow >= 0 && lev_min == lev_max));
 
    std::vector< std::pair<int, AmrBox_t> > isects;
 
    for (int lev = lev_max; lev >= lev_min; lev--)
    {
        const AmrIntVect_t& iv = Index(p, ip, lev);
        const AmrGrid_t& ba = ParticleBoxArray(lev);
        PAssert(ba.ixType().cellCentered());
 
        if (lev == (int)p.Level[ip]) {
            // The fact that we are here means this particle does not belong to any finer grids.
            if (0 <= p.Grid[ip] && p.Grid[ip] < ba.size()) {
                const AmrBox_t& bx = ba.getCellCenteredBox(p.Grid[ip]);
                const AmrBox_t& gbx = amrex::grow(bx,nGrow);
                if (gbx.contains(iv)) {
//                     if (bx != pld.m_gridbox || !pld.m_tilebox.contains(iv)) {
//                         pld.m_tile = getTileIndex(iv, bx, pld.m_tilebox);
//                         pld.m_gridbox = bx;
//                     }
                    return true;
                }
            }
        }
 
        ba.intersections(AmrBox_t(iv, iv), isects, true, nGrow);
 
        if (!isects.empty()) {
            p.Level[ip]  = lev;
            p.Grid[ip] = isects[0].first;
 
            return true;
        }
    }
    return false;
}
 
 
//Function from AMReX adjusted to work with Ippl AmrParticleBase class
//Checks/sets whether the particle has crossed a periodic boundary in such a way
//that it is on levels lev_min and higher.
template <class T, unsigned Dim>
bool BoxLibLayout<T, Dim>::EnforcePeriodicWhere (AmrParticleBase< BoxLibLayout<T,Dim> >& p,
                                                      const unsigned int ip,
                                                      int lev_min,
                                                      int lev_max) const
{
    if (!Geom(0).isAnyPeriodic()) return false;
 
    if (lev_max == -1)
        lev_max = finestLevel();
 
    PAssert(lev_max <= finestLevel());
    //
    // Create a copy "dummy" particle to check for periodic outs.
    //
    SingleParticlePos_t R = p.R[ip];
 
    if (PeriodicShift(R)) {
        std::vector< std::pair<int, AmrBox_t> > isects;
 
        for (int lev = lev_max; lev >= lev_min; lev--) {
            const AmrIntVect_t& iv = Index(R, lev);
            const AmrGrid_t& ba = ParticleBoxArray(lev);
 
            ba.intersections(AmrBox_t(iv,iv),isects,true,0);
 
            if (!isects.empty()) {
                D_TERM(p.R[ip][0] = R[0];,
                       p.R[ip][1] = R[1];,
                       p.R[ip][2] = R[2];);
 
                p.Level[ip]  = lev;
                p.Grid[ip] = isects[0].first;
 
                return true;
            }
        }
    }
 
    return false;
}
 
 
// Function from AMReX adjusted to work with Ippl AmrParticleBase class
// Returns true if the particle was shifted.
template <class T, unsigned Dim>
bool BoxLibLayout<T, Dim>::PeriodicShift (SingleParticlePos_t R) const
{
  //
    // This routine should only be called when Where() returns false.
    //
    //
    // We'll use level 0 stuff since ProbLo/ProbHi are the same for every level.
    //
    const AmrGeometry_t& geom    = Geom(0);
    const AmrBox_t&      dmn     = geom.Domain();
    const AmrIntVect_t&  iv      = Index(R, 0);
    bool            shifted = false;
 
    for (int i = 0; i < AMREX_SPACEDIM; i++) {
        if (!geom.isPeriodic(i)) continue;
 
        if (iv[i] > dmn.bigEnd(i)) {
            if (R[i] == geom.ProbHi(i)) {
                //
                // Don't let particles lie exactly on the domain face.
                // Force the particle to be outside the domain so the
                // periodic shift will bring it back inside.
                //
                R[i] += .125*geom.CellSize(i);
            }
            R[i] -= geom.ProbLength(i);
 
            if (R[i] <= geom.ProbLo(i))
                //
                // This can happen due to precision issues.
                //
                R[i] += .125*geom.CellSize(i);
 
            PAssert(R[i] >= geom.ProbLo(i));
 
            shifted = true;
 
        } else if (iv[i] < dmn.smallEnd(i)) {
            if (R[i] == geom.ProbLo(i)) {
                //
                // Don't let particles lie exactly on the domain face.
                // Force the particle to be outside the domain so the
                // periodic shift will bring it back inside.
                //
                R[i] -= .125*geom.CellSize(i);
            }
            R[i] += geom.ProbLength(i);
 
            if (R[i] >= geom.ProbHi(i)) {
                //
                // This can happen due to precision issues.
                //
                R[i] -= .125*geom.CellSize(i);
            }
            PAssert(R[i] <= geom.ProbHi(i));
 
            shifted = true;
        }
    }
    //
    // The particle may still be outside the domain in the case
    // where we aren't periodic on the face out which it travelled.
    //
    return shifted;
}
 
 
template <class T, unsigned Dim>
void BoxLibLayout<T, Dim>::locateParticle(
    AmrParticleBase< BoxLibLayout<T,Dim> >& p,
    const unsigned int ip,
    int lev_min, int lev_max, int nGrow) const
{
    bool outside = D_TERM( p.R[ip](0) <  AmrGeometry_t::ProbLo(0)
                        || p.R[ip](0) >= AmrGeometry_t::ProbHi(0),
                        || p.R[ip](1) <  AmrGeometry_t::ProbLo(1)
                        || p.R[ip](1) >= AmrGeometry_t::ProbHi(1),
                        || p.R[ip](2) <  AmrGeometry_t::ProbLo(2)
                        || p.R[ip](2) >= AmrGeometry_t::ProbHi(2));
 
    bool success = false;
 
    if (outside) {
        // Note that EnforcePeriodicWhere may shift the particle if it is successful.
        success = EnforcePeriodicWhere(p, ip, lev_min, lev_max);
        if (!success && lev_min == 0) {
            // The particle has left the domain; invalidate it.
            p.destroy(1, ip);
            success = true;
 
            /* We shouldn't lose particles since they are mapped to be within
             * [-1, 1]^3.
             */
            throw OpalException("BoxLibLayout::locateParticle()",
                                "We're losing particles although we shouldn't");
 
        }
    } else {
        success = Where(p, ip, lev_min, lev_max);
    }
 
    if (!success) {
        success = (nGrow > 0) && Where(p, ip, lev_min, lev_min, nGrow);
    }
 
    if (!success) {
        std::stringstream ss;
        ss << "Invalid particle with ID " << ip << " at position " << p.R[ip] << ".";
        throw OpalException("BoxLibLayout::locateParticle()", ss.str());
    }
}
 
 
// overwritten functions
template <class T, unsigned Dim>
bool BoxLibLayout<T, Dim>::LevelDefined (int level) const {
    return level <= this->maxLevel_m && !m_ba[level].empty() && !m_dmap[level].empty();
}
 
 
template <class T, unsigned Dim>
int BoxLibLayout<T, Dim>::finestLevel () const {
    return this->finestLevel_m;
}
 
 
template <class T, unsigned Dim>
int BoxLibLayout<T, Dim>::maxLevel () const {
    return this->maxLevel_m;
}
 
 
template <class T, unsigned Dim>
typename BoxLibLayout<T, Dim>::AmrIntVect_t
    BoxLibLayout<T, Dim>::refRatio (int level) const {
    return refRatio_m[level];
}
 
 
template <class T, unsigned Dim>
int BoxLibLayout<T, Dim>::MaxRefRatio (int level) const {
    int maxval = 0;
    for (int n = 0; n<AMREX_SPACEDIM; n++)
        maxval = std::max(maxval, refRatio_m[level][n]);
    return maxval;
}
 
 
template <class T, unsigned Dim>
void BoxLibLayout<T, Dim>::initBaseBox_m(int nGridPoints,
                                         int maxGridSize,
                                         double dh) {
    // physical box (in meters)
    AmrDomain_t real_box;
    for (int d = 0; d < AMREX_SPACEDIM; ++d) {
 
        PAssert(lowerBound[d] < 0);
        PAssert(upperBound[d] > 0);
 
        real_box.setLo(d, lowerBound[d] * (1.0 + dh));
        real_box.setHi(d, upperBound[d] * (1.0 + dh));
    }
 
    AmrGeometry_t::ProbDomain(real_box);
 
    // define underlying box for physical domain
    AmrIntVect_t domain_lo(0 , 0, 0);
    AmrIntVect_t domain_hi(nGridPoints - 1, nGridPoints - 1, nGridPoints - 1);
    const AmrBox_t domain(domain_lo, domain_hi);
 
    // use Cartesian coordinates
    int coord = 0;
 
    // Dirichlet boundary conditions
    int is_per[AMREX_SPACEDIM];
    for (int i = 0; i < AMREX_SPACEDIM; i++)
        is_per[i] = 0;
 
    AmrGeometry_t geom;
    geom.define(domain, &real_box, coord, is_per);
 
    AmrGrid_t ba;
    ba.define(domain);
    // break the BoxArrays at both levels into max_grid_size^3 boxes
    ba.maxSize(maxGridSize);
 
    AmrProcMap_t dmap;
    dmap.define(ba, Ippl::getNodes());
 
    // set protected ParGDB member variables
    this->m_geom.resize(1);
    this->m_geom[0] = geom;
 
    this->m_dmap.resize(1);
    this->m_dmap[0] = dmap;
 
    this->m_ba.resize(1);
    this->m_ba[0] = ba;
 
    this->m_nlevels = ba.size();
}
 
#endif