/**************************************************************************
* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
*                                                                        *
* Author: The ALICE Off-line Project.                                    *
* Contributors are mentioned in the code where appropriate.              *
*                                                                        *
* Permission to use, copy, modify and distribute this software and its   *
* documentation strictly for non-commercialf purposes is hereby granted   *
* without fee, provided that the above copyright notice appears in all   *
* copies and that both the copyright notice and this permission notice   *
* appear in the supporting documentation. The authors make no claims     *
* about the suitability of this software for any purpose. It is          *
* provided "as is" without express or implied warranty.                  *
**************************************************************************/

/* $Id: AliTRDtrackingResolution.cxx 27496 2008-07-22 08:35:45Z cblume $ */

////////////////////////////////////////////////////////////////////////////
//                                                                        //
//  TRD tracking resolution                                               //
//
// The class performs resolution and residual studies 
// of the TRD tracks for the following quantities :
//   - spatial position (y, [z])
//   - angular (phi) tracklet
//   - momentum at the track level
// 
// The class has to be used for regular detector performance checks using the official macros:
//   - $ALICE_ROOT/TRD/qaRec/run.C
//   - $ALICE_ROOT/TRD/qaRec/makeResults.C
// 
// For stand alone usage please refer to the following example: 
// {  
//   gSystem->Load("libANALYSIS.so");
//   gSystem->Load("libTRDqaRec.so");
//   AliTRDtrackingResolution *res = new AliTRDtrackingResolution();
//   //res->SetMCdata();
//   //res->SetVerbose();
//   //res->SetVisual();
//   res->Load("TRD.TaskResolution.root");
//   if(!res->PostProcess()) return;
//   res->GetRefFigure(0);
// }  
//
//  Authors:                                                              //
//    Alexandru Bercuci <A.Bercuci@gsi.de>                                //
//    Markus Fasel <M.Fasel@gsi.de>                                       //
//                                                                        //
////////////////////////////////////////////////////////////////////////////

#include <cstring>

#include <TSystem.h>
#include <TObjArray.h>
#include <TH2.h>
#include <TH1.h>
#include <TF1.h>
#include <TCanvas.h>
#include <TProfile.h>
#include <TGraphErrors.h>
#include <TMath.h>
#include "TTreeStream.h"
#include "TGeoManager.h"

#include "AliAnalysisManager.h"
#include "AliTrackReference.h"
#include "AliTrackPointArray.h"
#include "AliCDBManager.h"

#include "AliTRDSimParam.h"
#include "AliTRDgeometry.h"
#include "AliTRDpadPlane.h"
#include "AliTRDcluster.h"
#include "AliTRDseedV1.h"
#include "AliTRDtrackV1.h"
#include "AliTRDtrackerV1.h"
#include "AliTRDReconstructor.h"
#include "AliTRDrecoParam.h"

#include "AliTRDtrackInfo/AliTRDtrackInfo.h"
#include "AliTRDtrackingResolution.h"

ClassImp(AliTRDtrackingResolution)

//________________________________________________________
AliTRDtrackingResolution::AliTRDtrackingResolution()
  :AliTRDrecoTask("Resolution", "Tracking Resolution")
  ,fStatus(0)
  ,fReconstructor(0x0)
  ,fGeo(0x0)
  ,fGraphS(0x0)
  ,fGraphM(0x0)
{
  fReconstructor = new AliTRDReconstructor();
  fReconstructor->SetRecoParam(AliTRDrecoParam::GetLowFluxParam());
  fGeo = new AliTRDgeometry();
}

//________________________________________________________
AliTRDtrackingResolution::~AliTRDtrackingResolution()
{
  if(fGraphS){fGraphS->Delete(); delete fGraphS;}
  if(fGraphM){fGraphM->Delete(); delete fGraphM;}
  delete fGeo;
  delete fReconstructor;
  if(gGeoManager) delete gGeoManager;
}


//________________________________________________________
void AliTRDtrackingResolution::CreateOutputObjects()
{
  // spatial resolution
  OpenFile(0, "RECREATE");

  fContainer = Histos();

  // cluster to tracklet residuals [2]
  fContainer->AddAt(new TH2I("fYClRes", "Clusters Residuals", 21, -21., 21., 100, -.5, .5), kClusterYResidual);
//   // tracklet to Riemann fit residuals [2]
//   fContainer->AddAt(new TH2I("fYTrkltRRes", "Tracklet Riemann Residuals", 21, -21., 21., 100, -.5, .5), kTrackletRiemanYResidual);
//   fContainer->AddAt(new TH2I("fAngleTrkltRRes", "Tracklet Riemann Angular Residuals", 21, -21., 21., 100, -.5, .5), kTrackletRiemanAngleResidual);
//   fContainer->AddAt(new TH2I("fYTrkltKRes", "Tracklet Kalman Residuals", 21, -21., 21., 100, -.5, .5), kTrackletKalmanYResidual);
//   fContainer->AddAt(new TH2I("fAngleTrkltKRes", "Tracklet Kalman Angular Residuals", 21, -21., 21., 100, -.5, .5), kTrackletKalmanAngleResidual);

  // Resolution histos
  if(HasMCdata()){
    // cluster y resolution [0]
    fContainer->AddAt(new TH2I("fCY", "Cluster Resolution", 31, -31., 31., 100, -.5, .5), kClusterYResolution);
    // tracklet y resolution [0]
    fContainer->AddAt(new TH2I("fY", "Tracklet Resolution", 31, -31., 31., 100, -.5, .5), kTrackletYResolution);
    // tracklet angular resolution [1]
    fContainer->AddAt(new TH2I("fPhi", "Tracklet Angular Resolution", 31, -31., 31., 100, -10., 10.), kTrackletAngleResolution);

//     // Riemann track resolution [y, z, angular]
//     fContainer->AddAt(new TH2I("fYRT", "Track Riemann Y Resolution", 21, -21., 21., 100, -.5, .5), kTrackRYResolution);
//     fContainer->AddAt(new TH2I("fZRT", "Track Riemann Z Resolution", 21, -21., 21., 100, -.5, .5), kTrackRZResolution);
//     fContainer->AddAt(new TH2I("fPhiRT", "Track Riemann Angular Resolution", 21, -21., 21., 100, -10., 10.), kTrackRAngleResolution);
// 
//     Kalman track resolution [y, z, angular]
//     fContainer->AddAt(new TH2I("fYKT", "", 21, -21., 21., 100, -.5, .5), kTrackKYResolution);
//     fContainer->AddAt(new TH2I("fZKT", "", 21, -21., 21., 100, -.5, .5), kTrackKZResolution);
//     fContainer->AddAt(new TH2I("fPhiKT", "", 21, -21., 21., 100, -10., 10.), kTrackKAngleResolution);
  }
}

//________________________________________________________
void AliTRDtrackingResolution::Exec(Option_t *)
{
  // spatial Resolution: res = pos_{Tracklet}(x = x_{Anode wire}) - pos_{TrackRef}(x = x_{Anode wire})
  // angular Resolution: res = Tracklet angle - TrackRef Angle

  Int_t nTrackInfos = fTracks->GetEntriesFast();
  if(fDebugLevel>=2 && nTrackInfos){ 
    printf("Event[%d] TrackInfos[%d]\n", (Int_t)AliAnalysisManager::GetAnalysisManager()->GetCurrentEntry(), nTrackInfos);
  }
  const Int_t kNLayers = AliTRDgeometry::kNlayer;
  Int_t pdg, nly, ncrs;
  Double_t p, dy, theta/*, dphi, dymc, dzmc, dphimc*/;
  Float_t fP[kNLayers], fX[kNLayers], fY[kNLayers], fZ[kNLayers], fPhi[kNLayers], fTheta[kNLayers]; // phi/theta angle per layer
  Bool_t fMCMap[kNLayers], fLayerMap[kNLayers]; // layer map

  AliTRDpadPlane *pp = 0x0;
  AliTrackPoint tr[kNLayers], tk[kNLayers];
  AliExternalTrackParam *fOp = 0x0;
  AliTRDtrackV1 *fTrack = 0x0;
  AliTRDtrackInfo *fInfo = 0x0;
  for(Int_t iTI = 0; iTI < nTrackInfos; iTI++){
    // check if ESD and MC-Information are available
    if(!(fInfo = dynamic_cast<AliTRDtrackInfo *>(fTracks->UncheckedAt(iTI)))) continue;
    if(!(fTrack = fInfo->GetTrack())) continue;
    if(!(fOp = fInfo->GetOuterParam())) continue;
    pdg = fInfo->GetPDG();
    nly = 0; ncrs = 0; theta = 0.;

    if(fDebugLevel>=3) printf("\tDoing track[%d] NTrackRefs[%d]\n", iTI, fInfo->GetNTrackRefs());

    p = fOp->P();
    Int_t npts = 0;
    memset(fP, 0, kNLayers*sizeof(Float_t));
    memset(fX, 0, kNLayers*sizeof(Float_t));
    memset(fY, 0, kNLayers*sizeof(Float_t));
    memset(fZ, 0, kNLayers*sizeof(Float_t));
    memset(fPhi, 0, kNLayers*sizeof(Float_t));
    memset(fTheta, 0, kNLayers*sizeof(Float_t));
    memset(fLayerMap, 0, kNLayers*sizeof(Bool_t));
    memset(fMCMap, 0, kNLayers*sizeof(Bool_t));
    AliTRDseedV1 *fTracklet = 0x0;
    for(Int_t iplane = 0; iplane < kNLayers; iplane++){
      if(!(fTracklet = fTrack->GetTracklet(iplane))) continue;
      if(!fTracklet->IsOK()) continue;

      // Book point arrays
      fLayerMap[iplane] = kTRUE;
      tr[npts].SetXYZ(fTracklet->GetX0(), 0., 0.);
      tk[npts].SetXYZ(fTracklet->GetX0(), fTracklet->GetYfit(0), fTracklet->GetZfit(0));
      npts++;

      if(fDebugLevel>=4) printf("\t\tLy[%d] X0[%6.3f] Ncl[%d]\n", iplane, fTracklet->GetX0(), fTracklet->GetN());

      // define reference values
      fP[iplane]   = p;
      fX[iplane]   = fTracklet->GetX0();
      fY[iplane]   = fTracklet->GetYref(0);
      fZ[iplane]   = fTracklet->GetZref(0);
      fPhi[iplane] = TMath::ATan(fTracklet->GetYref(1));
      fTheta[iplane] = TMath::ATan(fTracklet->GetZref(1));
      

      // RESOLUTION (compare to MC)
      if(HasMCdata()){
        if(fInfo->GetNTrackRefs() >= 2){ 
          Double_t pmc, ymc, zmc, phiMC, thetaMC;
          if(Resolution(fTracklet, fInfo, pmc, ymc, zmc, phiMC, thetaMC)){ 
            fMCMap[iplane] = kTRUE;
            fP[iplane]     = pmc;
            fY[iplane]     = ymc;
            fZ[iplane]     = zmc;
            fPhi[iplane]   = phiMC;
            fTheta[iplane] = thetaMC;
          }
        }
      }
      Float_t phi   = fPhi[iplane]*TMath::RadToDeg();
      theta += fTheta[iplane]; nly++;
      if(fTracklet->GetNChange()) ncrs++;

      // Do clusters residuals
      if(!fTracklet->Fit(kFALSE)) continue;
      AliTRDcluster *c = 0x0;
      for(Int_t ic=AliTRDseed::knTimebins-1; ic>=0; ic--){
        if(!(c = fTracklet->GetClusters(ic))) continue;

        dy = fTracklet->GetYat(c->GetX()) - c->GetY();
        ((TH2I*)fContainer->At(kClusterYResidual))->Fill(phi, dy);

        if(fDebugLevel>=2){
          Float_t q = c->GetQ();
          // Get z-position with respect to anode wire
          AliTRDSimParam    *simParam    = AliTRDSimParam::Instance();
          Int_t det = c->GetDetector();
          Float_t x = c->GetX();
          Float_t z = fZ[iplane]-(fX[iplane]-x)*TMath::Tan(fTheta[iplane]);
          Int_t stack = fGeo->GetStack(det);
          pp = fGeo->GetPadPlane(iplane, stack);
          Float_t row0 = pp->GetRow0();
          Float_t d  =  row0 - z + simParam->GetAnodeWireOffset();
          d -= ((Int_t)(2 * d)) / 2.0;
          if (d > 0.25) d  = 0.5 - d;
  
          (*fDebugStream) << "ResidualClusters"
            << "ly="   << iplane
            << "stk="  << stack
            << "pdg="  << pdg
            << "phi="  << fPhi[iplane]
            << "tht="  << fTheta[iplane]
            << "q="    << q
            << "x="    << x
            << "z="    << z
            << "d="    << d
            << "dy="   << dy
            << "\n";
        }
      }
      pp = 0x0;
    }
    if(nly) theta /= nly; 
    if(fDebugLevel>=1){
      (*fDebugStream) << "TrackStatistics"
        << "nly="   << nly
        << "ncrs="  << ncrs
        << "tht="   << theta
        << "\n";
    }


//     // this protection we might drop TODO
//     if(fTrack->GetNumberOfTracklets() < 6) continue;
// 
//     AliTRDtrackerV1::FitRiemanTilt(fTrack, 0x0, kTRUE, npts, tr);
//     Int_t iref = 0;
//     for(Int_t ip=0; ip<kNLayers; ip++){
//       if(!fLayerMap[ip]) continue;
//       fTracklet = fTrack->GetTracklet(ip);
//       // recalculate fit based on the new tilt correction
//       fTracklet->Fit();
// 
//       dy = fTracklet->GetYfit(0) - tr[iref].GetY();
//       ((TH2I*)fContainer->At(kTrackletRiemanYResidual))->Fill(fPhi[ip]*TMath::RadToDeg(), dy);
// 
//       dphi = fTracklet->GetYfit(1)- fTracklet->GetYref(1);
//       ((TH2I*)fContainer->At(kTrackletRiemanAngleResidual))->Fill(fPhi[ip]*TMath::RadToDeg(), dphi);
// 
//       if(HasMCdata()){
//         dymc = fY[ip] - tr[iref].GetY();
//         ((TH2I*)fContainer->At(kTrackRYResolution))->Fill(fPhi[ip]*TMath::RadToDeg(), dymc);
// 
//         dzmc = fZ[ip] - tr[iref].GetZ();
//         ((TH2I*)fContainer->At(kTrackRZResolution))->Fill(fPhi[ip]*TMath::RadToDeg(), dzmc);
// 
//         dphimc = fPhi[ip] - fTracklet->GetYfit(1);
//         ((TH2I*)fContainer->At(kTrackRAngleResolution))->Fill(fPhi[ip]*TMath::RadToDeg(), dphimc);
//       }
// 
//       iref++;
// 
//       if(fDebugLevel>=1){
//         (*fDebugStream) << "RiemannTrack"
//           << "ly="    << ip
//           << "mc="    << fMCMap[ip]
//           << "p="     << fP[ip]
//           << "phi="   << fPhi[ip]
//           << "tht="   << fTheta[ip]
//           << "dy="    << dy
//           << "dphi="  << dphi
//           << "dymc="  << dymc
//           << "dzmc="  << dzmc
//           << "dphimc="<< dphimc
//           << "\n";
//       }
//     }

//  if(!gGeoManager) TGeoManager::Import("geometry.root");
//     AliTRDtrackerV1::FitKalman(fTrack, 0x0, kFALSE, nc, tr);
//     for(Int_t ip=0; ip<nc; ip++){
//       dy = cl[ip].GetY() - tr[ip].GetY();
//      ((TH2I*)fContainer->At(kTrackletKalmanYResidual))->Fill(phi*TMath::RadToDeg(), dy);
//       dz = cl[ip].GetZ() - tr[ip].GetZ();
//       if(fDebugLevel>=1){
//         (*fDebugStream) << "KalmanTrack"
//           << "dy="		  << dy
//           << "dz="	 	  << dz
// /*          << "phi="			<< phi
//           << "theta="		<< theta
//           << "dphi="		<< dphi*/
//           << "\n";
//       }
//     }    


  }
  PostData(0, fContainer);
}

//________________________________________________________
void AliTRDtrackingResolution::GetRefFigure(Int_t ifig)
{
  TAxis *ax = 0x0;
  TGraphErrors *g = 0x0;
  switch(ifig){
  case kClusterYResidual:
    if(!(g = (TGraphErrors*)fGraphS->At(kClusterYResidual))) break;
    g->Draw("apl");
    ax = g->GetHistogram()->GetYaxis();
    ax->SetRangeUser(-.5, 1.);
    ax->SetTitle("Clusters Y Residuals #sigma/#mu [mm]");
    ax = g->GetHistogram()->GetXaxis();
    ax->SetTitle("tg(#phi)");
    if(!(g = (TGraphErrors*)fGraphM->At(kClusterYResidual))) break;
    g->Draw("pl");
    return;
  case kClusterYResolution:
    if(!(g = (TGraphErrors*)fGraphS->At(kClusterYResolution))) break;
    ax = g->GetHistogram()->GetYaxis();
    ax->SetRangeUser(-.5, 1.);
    ax->SetTitle("Cluster Y Resolution #sigma/#mu [mm]");
    ax = g->GetHistogram()->GetXaxis();
    ax->SetTitle("tg(#phi)");
    g->Draw("apl");
    if(!(g = (TGraphErrors*)fGraphM->At(kClusterYResolution))) break;
    g->Draw("pl");
    return;
  case kTrackletYResolution:
    if(!(g = (TGraphErrors*)fGraphS->At(kTrackletYResolution))) break;
    ax = g->GetHistogram()->GetYaxis();
    ax->SetRangeUser(-.5, 1.);
    ax->SetTitle("Tracklet Y Resolution #sigma/#mu [mm]");
    ax = g->GetHistogram()->GetXaxis();
    ax->SetTitle("#phi [deg]");
    g->Draw("apl");
    if(!(g = (TGraphErrors*)fGraphM->At(kTrackletYResolution))) break;
    g->Draw("pl");
    return;
  case kTrackletAngleResolution:
    if(!(g = (TGraphErrors*)fGraphS->At(kTrackletAngleResolution))) break;
    ax = g->GetHistogram()->GetYaxis();
    ax->SetRangeUser(-.05, .2);
    ax->SetTitle("Tracklet Angular Resolution #sigma/#mu [deg]");
    ax = g->GetHistogram()->GetXaxis();
    ax->SetTitle("#phi [deg]");
    g->Draw("apl");
    if(!(g = (TGraphErrors*)fGraphM->At(kTrackletAngleResolution))) break;
    g->Draw("pl");
    return;
  default:
    AliInfo(Form("Reference plot [%d] not implemented yet", ifig));
    return;
  }
  AliInfo(Form("Reference plot [%d] missing result", ifig));
}


//________________________________________________________
Bool_t AliTRDtrackingResolution::Resolution(AliTRDseedV1 *tracklet, AliTRDtrackInfo *fInfo, Double_t &p, Double_t &ymc, Double_t &zmc, Double_t &phi, Double_t &theta)
{

  AliTrackReference *fTrackRefs[2] = {0x0, 0x0};
  Float_t x0  = tracklet->GetX0();
  Float_t tilt= tracklet->GetTilt();
  Int_t cross = tracklet->GetNChange();
  Int_t det = tracklet->GetDetector();
  Int_t pdg = fInfo->GetPDG();

  // check for 2 track ref where the radial position has a distance less than 3.7mm
  Int_t nFound = 0;
  for(Int_t itr = 0; itr < AliTRDtrackInfo::kNTrackRefs; itr++){
    if(!(fTrackRefs[nFound] = fInfo->GetTrackRef(itr))) break;

    if(fDebugLevel>=5) printf("\t\tref[%2d] x[%6.3f]\n", itr, fTrackRefs[nFound]->LocalX());
    if(TMath::Abs(x0 - fTrackRefs[nFound]->LocalX()) > 3.7) continue;
    nFound++;
    if(nFound == 2) break;
  }
  if(nFound < 2){ 
    if(fDebugLevel>=3) printf("\t\tMissing track ref x0[%6.3f] ly[%d] nref[%d]\n", x0, tracklet->GetPlane(), fInfo->GetMCinfo()->GetNTrackRefs());
    return kFALSE;
  }
  // We found 2 track refs for the tracklet, get y and z at the anode wire by a linear approximation


  // RESOLUTION
  Double_t dx = fTrackRefs[1]->LocalX() - fTrackRefs[0]->LocalX();
  if(dx <= 0. || TMath::Abs(dx-3.7)>1.E-3){
    if(fDebugLevel>=3) printf("\t\tTrack ref with wrong radial distances refX0[%6.3f] refX1[%6.3f]\n", fTrackRefs[0]->LocalX(), fTrackRefs[1]->LocalX());
    return kFALSE;
  }

  Double_t dydx = (fTrackRefs[1]->LocalY() - fTrackRefs[0]->LocalY()) / dx;
  Double_t dzdx = (fTrackRefs[1]->Z() - fTrackRefs[0]->Z()) / dx;
  Double_t dx0 = fTrackRefs[1]->LocalX() - tracklet->GetX0();
  ymc =  fTrackRefs[1]->LocalY() - dydx*dx0;
  zmc =  fTrackRefs[1]->Z() - dzdx*dx0;
  
  // recalculate tracklet based on the MC info
  AliTRDseedV1 tt(*tracklet);
  tt.SetZref(0, zmc);
  tt.SetZref(1, dzdx); 
  tt.Fit();
  Double_t dy = tt.GetYfit(0) - ymc;
  Double_t dz = 100.;
  if(cross){
    Double_t *xyz = tt.GetCrossXYZ();
    dz = xyz[2] - (zmc - (x0 - xyz[0])*dzdx) ;
  }
  p = fTrackRefs[0]->P();

  phi   = TMath::ATan(dydx);
  theta = TMath::ATan(dzdx);
  Double_t dphi   = TMath::ATan(tt.GetYfit(1)) - phi;
  if(fDebugLevel>=4) printf("\t\tdx[%6.4f] dy[%6.4f] dz[%6.4f] dphi[%6.4f] \n", dx, dy, dz, dphi);
  
  // Fill Histograms
  ((TH2I*)fContainer->At(kTrackletYResolution))->Fill(phi*TMath::RadToDeg(), dy);
  ((TH2I*)fContainer->At(kTrackletAngleResolution))->Fill(phi*TMath::RadToDeg(), dphi*TMath::RadToDeg());

  // Fill Debug Tree
  if(fDebugLevel>=1){
    (*fDebugStream) << "ResolutionTrklt"
      << "det="	 	  << det
      << "pdg="     << pdg
      << "p="       << p
      << "ymc="     << ymc
      << "zmc="     << zmc
      << "dydx="    << dydx
      << "dzdx="    << dzdx
      << "cross="   << cross
      << "dy="		  << dy
      << "dz="	 	  << dz
      << "dphi="		<< dphi
      << "\n";
  }

  AliTRDpadPlane *pp = fGeo->GetPadPlane(AliTRDgeometry::GetLayer(det), AliTRDgeometry::GetStack(det));
  Float_t z0 = pp->GetRow0() + AliTRDSimParam::Instance()->GetAnodeWireOffset();

  AliTRDcluster *c = 0x0;
  tracklet->ResetClusterIter(kFALSE);
  while((c = tracklet->PrevCluster())){
    Float_t  q = TMath::Abs(c->GetQ());
    Float_t xc = c->GetX();
    Float_t yc = c->GetY();
    Float_t zc = c->GetZ();
    dx = x0 - xc; 
    Float_t yt = ymc - dx*dydx;
    Float_t zt = zmc - dx*dzdx; 
    dy = yt - (yc - tilt*(zc-zt));

    // Fill Histograms
    if(q>100.) ((TH2I*)fContainer->At(kClusterYResolution))->Fill(phi*TMath::RadToDeg(), dy);
    
    // Fill Debug Tree
    if(fDebugLevel>=1){
      Float_t d = z0 - zt;
      d -= ((Int_t)(2 * d)) / 2.0;
      (*fDebugStream) << "ResolutionClstr"
        << "pdg="     << pdg
        << "p="       << p
        << "phi="			<< phi
        << "tht="		  << theta
        << "dy="		  << dy
        << "crs="	 	  << cross
        << "q="       << q
        << "d="       << d
        << "\n";
    }
  }

  return kTRUE;
}

//________________________________________________________
Bool_t AliTRDtrackingResolution::PostProcess()
{
  //fContainer = dynamic_cast<TObjArray*>(GetOutputData(0));
  if (!fContainer) {
    Printf("ERROR: list not available");
    return kFALSE;
  }
  fNRefFigures = fContainer->GetEntriesFast();
  if(!fGraphS){ 
    fGraphS = new TObjArray(fNRefFigures);
    fGraphS->SetOwner();
  }
  if(!fGraphM){ 
    fGraphM = new TObjArray(fNRefFigures);
    fGraphM->SetOwner();
  }

  TH2I *h2 = 0x0;
  TH1D *h = 0x0;
  TGraphErrors *gm = 0x0, *gs = 0x0;

  // define models
  TF1 f("f1", "gaus", -.5, .5);  

  TF1 fb("fb", "[0]*exp(-0.5*((x-[1])/[2])**2)+[3]", -.5, .5);

  TF1 fc("fc", "[0]*exp(-0.5*((x-[1])/[2])**2)+[3]*exp(-0.5*((x-[4])/[5])**2)", -.5, .5);

  TCanvas *c = 0x0;
  if(IsVisual()) c = new TCanvas("c", Form("%s Visual", GetName()), 500, 500);
  char opt[5];
  sprintf(opt, "%c%c", IsVerbose() ? ' ' : 'Q', IsVisual() ? ' ': 'N');


  //PROCESS RESIDUAL DISTRIBUTIONS

  // Clusters residuals
  h2 = (TH2I *)(fContainer->At(kClusterYResidual));
  gm = new TGraphErrors(h2->GetNbinsX());
  gm->SetLineColor(kBlue);
  gm->SetMarkerStyle(7);
  gm->SetMarkerColor(kBlue);
  gm->SetNameTitle("clm", "");
  fGraphM->AddAt(gm, kClusterYResidual);
  gs = new TGraphErrors(h2->GetNbinsX());
  gs->SetLineColor(kRed);
  gs->SetMarkerStyle(23);
  gs->SetMarkerColor(kRed);
  gs->SetNameTitle("cls", "");
  fGraphS->AddAt(gs, kClusterYResidual);
  for(Int_t ibin = 1; ibin <= h2->GetNbinsX(); ibin++){
    Double_t phi = h2->GetXaxis()->GetBinCenter(ibin);
    h = h2->ProjectionY("py", ibin, ibin);
    AdjustF1(h, &fc);

    if(IsVisual()){c->cd(); c->SetLogy();}
    h->Fit(&fc, opt, "", -0.5, 0.5);
    if(IsVisual()){c->Modified(); c->Update(); gSystem->Sleep(500);}
    
    gm->SetPoint(ibin - 1, TMath::Tan(phi*TMath::DegToRad()), 10.*fc.GetParameter(1));
    gm->SetPointError(ibin - 1, 0., 10.*fc.GetParError(1));
    gs->SetPoint(ibin - 1, TMath::Tan(phi*TMath::DegToRad()), 10.*fc.GetParameter(2));
    gs->SetPointError(ibin - 1, 0., 10.*fc.GetParError(2));
  }


  //PROCESS RESOLUTION DISTRIBUTIONS

  if(HasMCdata()){
    // cluster y resolution
    h2 = (TH2I*)fContainer->At(kClusterYResolution);
    gm = new TGraphErrors(h2->GetNbinsX());
    gm->SetLineColor(kBlue);
    gm->SetMarkerStyle(7);
    gm->SetMarkerColor(kBlue);
    gm->SetNameTitle("clym", "");
    fGraphM->AddAt(gm, kClusterYResolution);
    gs = new TGraphErrors(h2->GetNbinsX());
    gs->SetLineColor(kRed);
    gs->SetMarkerStyle(23);
    gs->SetMarkerColor(kRed);
    gs->SetNameTitle("clys", "");
    fGraphS->AddAt(gs, kClusterYResolution);
    for(Int_t iphi=1; iphi<=h2->GetNbinsX(); iphi++){
      h = h2->ProjectionY("py", iphi, iphi);
      AdjustF1(h, &fb);

      if(IsVisual()){c->cd(); c->SetLogy();}
      h->Fit(&fb, opt, "", -0.5, 0.5);
      if(IsVisual()){c->Modified(); c->Update(); gSystem->Sleep(500);}

      Double_t phi = h2->GetXaxis()->GetBinCenter(iphi);
      Int_t jphi = iphi -1;
      gm->SetPoint(jphi, TMath::Tan(phi*TMath::DegToRad()), 10.*fb.GetParameter(1));
      gm->SetPointError(jphi, 0., 10.*fb.GetParError(1));
      gs->SetPoint(jphi, TMath::Tan(phi*TMath::DegToRad()), 10.*fb.GetParameter(2));
      gs->SetPointError(jphi, 0., 10.*fb.GetParError(2));
    }
  
    // tracklet y resolution
    h2 = (TH2I*)fContainer->At(kTrackletYResolution);
    gm = new TGraphErrors(h2->GetNbinsX());
    gm->SetLineColor(kBlue);
    gm->SetMarkerStyle(7);
    gm->SetMarkerColor(kBlue);
    gm->SetNameTitle("trkltym", "");
    fGraphM->AddAt(gm, kTrackletYResolution);
    gs = new TGraphErrors(h2->GetNbinsX());
    gs->SetLineColor(kRed);
    gs->SetMarkerStyle(23);
    gs->SetMarkerColor(kRed);
    gs->SetNameTitle("trkltys", "");
    fGraphS->AddAt(gs, kTrackletYResolution);
    for(Int_t iphi=1; iphi<=h2->GetNbinsX(); iphi++){
      h = h2->ProjectionY("py", iphi, iphi);
      AdjustF1(h, &fb);

      if(IsVisual()){c->cd(); c->SetLogy();}
      h->Fit(&fb, opt, "", -0.5, 0.5);
      if(IsVisual()){c->Modified(); c->Update(); gSystem->Sleep(500);}

      Double_t phi = h2->GetXaxis()->GetBinCenter(iphi);
      Int_t jphi = iphi -1;
      gm->SetPoint(jphi, phi, 10.*fb.GetParameter(1));
      gm->SetPointError(jphi, 0., 10.*fb.GetParError(1));
      gs->SetPoint(jphi, phi, 10.*fb.GetParameter(2));
      gs->SetPointError(jphi, 0., 10.*fb.GetParError(2));
    }
  
    // tracklet phi resolution
    h2 = (TH2I*)fContainer->At(kTrackletAngleResolution);
    gm = new TGraphErrors(h2->GetNbinsX());
    gm->SetLineColor(kBlue);
    gm->SetMarkerStyle(7);
    gm->SetMarkerColor(kBlue);
    gm->SetNameTitle("trkltym", "");
    fGraphM->AddAt(gm, kTrackletAngleResolution);
    gs = new TGraphErrors(h2->GetNbinsX());
    gs->SetLineColor(kRed);
    gs->SetMarkerStyle(23);
    gs->SetMarkerColor(kRed);
    gs->SetNameTitle("trkltys", "");
    fGraphS->AddAt(gs, kTrackletAngleResolution);
    for(Int_t iphi=1; iphi<=h2->GetNbinsX(); iphi++){
      h = h2->ProjectionY("py", iphi, iphi);

      if(IsVisual()){c->cd(); c->SetLogy();}
      h->Fit(&f, opt, "", -0.5, 0.5);
      if(IsVisual()){c->Modified(); c->Update(); gSystem->Sleep(500);}

      Double_t phi = h2->GetXaxis()->GetBinCenter(iphi);
      Int_t jphi = iphi -1;
      gm->SetPoint(jphi, phi, f.GetParameter(1));
      gm->SetPointError(jphi, 0., f.GetParError(1));
      gs->SetPoint(jphi, phi, f.GetParameter(2));
      gs->SetPointError(jphi, 0., f.GetParError(2));
    }
  }
  if(c) delete c;

  return kTRUE;
}


//________________________________________________________
void AliTRDtrackingResolution::Terminate(Option_t *)
{
  if(fDebugStream){ 
    delete fDebugStream;
    fDebugStream = 0x0;
    fDebugLevel = 0;
  }
  if(HasPostProcess()) PostProcess();
}

//________________________________________________________
void AliTRDtrackingResolution::AdjustF1(TH1 *h, TF1 *f)
{
// Helper function to avoid duplication of code
// Make first guesses on the fit parameters

  // find the intial parameters of the fit !! (thanks George)
  Int_t nbinsy = Int_t(.5*h->GetNbinsX());
  Double_t sum = 0.;
  for(Int_t jbin=nbinsy-4; jbin<=nbinsy+4; jbin++) sum+=h->GetBinContent(jbin); sum/=9.;
  f->SetParLimits(0, 0., 3.*sum);
  f->SetParameter(0, .9*sum);

  f->SetParLimits(1, -.2, .2);
  f->SetParameter(1, 0.);

  f->SetParLimits(2, 0., 4.e-1);
  f->SetParameter(2, 2.e-2);
  if(f->GetNpar() <= 4) return;

  f->SetParLimits(3, 0., sum);
  f->SetParameter(3, .1*sum);

  f->SetParLimits(4, -.3, .3);
  f->SetParameter(4, 0.);

  f->SetParLimits(5, 0., 1.e2);
  f->SetParameter(5, 2.e-1);
}

//________________________________________________________
TObjArray* AliTRDtrackingResolution::Histos()
{
  if(!fContainer) fContainer  = new TObjArray(4);
  return fContainer;
}


//________________________________________________________
void AliTRDtrackingResolution::SetRecoParam(AliTRDrecoParam *r)
{

  fReconstructor->SetRecoParam(r);
}