[u/mrichter/AliRoot.git] / PWGHF / hfe / AliHFEtools.cxx

/**************************************************************************
* 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-commercial 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.                  *
**************************************************************************/
//
// Toolkit containing various usefull things
// Usable everywhere in the hfe software package
// For more information see the cxx file
//
// Authors
//   All authors of the HFE group
//
#include <TMath.h>
#include <TParticle.h>
#include "TH1.h"
#include "TH1D.h"
#include "TH2.h"
#include "TGraph.h"
#include "TGraphErrors.h"
#include "THnSparse.h"
#include "TAxis.h"
#include "TMath.h"
#include "TString.h"

#include "AliAODMCParticle.h"
#include "AliAODpidUtil.h"
#include "AliESDpid.h"
#include "AliLog.h"
#include "AliTPCPIDResponse.h"
#include "AliTOFPIDResponse.h"

#include "AliHFEtools.h"

ClassImp(AliHFEtools)

AliPIDResponse *AliHFEtools::fgDefaultPID = NULL;
Int_t AliHFEtools::fgLogLevel = 0;

//__________________________________________
AliHFEtools::AliHFEtools():
  TObject()
{
}

//__________________________________________
Double_t *AliHFEtools::MakeLinearBinning(Int_t nBins, Double_t ymin, Double_t ymax){
  //
  // Helper function for linearly binned array
  //
  Double_t *bins = new Double_t[nBins + 1];
  Double_t stepsize = (ymax - ymin) / static_cast<Double_t>(nBins);
  bins[0] = ymin;
  for(Int_t ibin = 1; ibin <= nBins; ibin++)
    bins[ibin] = bins[ibin-1] + stepsize;
  return bins;
}

//__________________________________________
Double_t *AliHFEtools::MakeLogarithmicBinning(Int_t nBins, Double_t ymin, Double_t ymax){
  //
  // Helper function for logartimically binned array
  //
  Double_t *bins = new Double_t[nBins+1];
  bins[0] = ymin;
  Double_t factor = TMath::Power(ymax/ymin, 1./nBins);
  for(Int_t ibin = 1; ibin <= nBins; ibin++){
    bins[ibin] = factor * bins[ibin-1];
  }
  return bins;
}

//_________________________________________
Bool_t AliHFEtools::BinLogAxis(TObject *o, Int_t dim){

  // 
  // converts the axis (defined by the dimension) of THx or THnSparse
  // object to Log scale. Number of bins and bin min and bin max are preserved
  //


  if(!o){
    AliError("Input histogram is null pointer");
    return kFALSE;    
  }
  
  TAxis *axis = 0x0;
  if(o->InheritsFrom("TH1")){
    TH1 *h1 = dynamic_cast<TH1F*>(o); 
    if(h1) axis = h1->GetXaxis();
  }
  else if(o->InheritsFrom("TH2")){
    TH2 *h2 = dynamic_cast<TH2F*>(o);
    if(h2 && 0 == dim){
      axis = h2->GetXaxis();
    }
    else if(h2 && 1 == dim){
      axis = h2->GetYaxis();
    }
     else{
       AliError("Only dim = 0 or 1 possible for TH2F");
     }
  }
  else if(o->InheritsFrom("THnSparse")){
    THnSparse *hs = dynamic_cast<THnSparse*>(o);
    if(hs) axis = hs->GetAxis(dim);
  }
  else{
    AliError("Type of input object not recognized, please check your code or update this finction");
    return kFALSE;
  }
  if(!axis){
    AliError(Form("Axis '%d' could not be identified in the object \n", dim));
    return kFALSE;
  }
  
  Int_t bins = axis->GetNbins();

  Double_t from = axis->GetXmin();
  if(from <= 0){
    AliError(Form("Log binning not possible for this axis [min = %f]\n", from));
  }
  Double_t to = axis->GetXmax();
  Double_t *newBins = new Double_t[bins+1];
  newBins[0] = from;
  Double_t factor = TMath::Power(to/from, 1./bins);
  for(Int_t i=1; i<=bins; ++i){
    newBins[i] = factor * newBins[i-1];
  }
  axis->Set(bins, newBins);
  delete[] newBins;

  return kTRUE;
}

//__________________________________________
Float_t AliHFEtools::GetRapidity(const TParticle *part){
  //
  // return rapidity
  //
  Float_t rapidity;
  if(!((part->Energy() - part->Pz())*(part->Energy() + part->Pz())>0)) rapidity=-999;
  else rapidity = 0.5*(TMath::Log((part->Energy()+part->Pz()) / (part->Energy()-part->Pz())));
  return rapidity;
}

//__________________________________________
Float_t AliHFEtools::GetRapidity(const AliAODMCParticle *part){
  // return rapidity

  Float_t rapidity;        
  if(!((part->E() - part->Pz())*(part->E() + part->Pz())>0)) rapidity=-999; 
  else rapidity = 0.5*(TMath::Log((part->E()+part->Pz()) / (part->E()-part->Pz()))); 
  return rapidity;
}

//__________________________________________
AliPIDResponse* AliHFEtools::GetDefaultPID(Bool_t isMC, Bool_t isESD){
  //
  // Get the default PID as singleton instance
  //
  if(!fgDefaultPID){

    if(isESD) fgDefaultPID = new AliESDpid;
    else fgDefaultPID = new AliAODpidUtil;
    Double_t tres = isMC ? 80. : 130.;
    fgDefaultPID->GetTOFResponse().SetTimeResolution(tres);

    // TPC Bethe Bloch parameters
    Double_t alephParameters[5];
    if(isMC){
      // simulation
      alephParameters[0] = 2.15898e+00/50.;
      alephParameters[1] = 1.75295e+01;
      alephParameters[2] = 3.40030e-09;
      alephParameters[3] = 1.96178e+00;
      alephParameters[4] = 3.91720e+00;
    } else {
      alephParameters[0] = 0.0283086/0.97;
      //alephParameters[0] = 0.0283086;
      alephParameters[1] = 2.63394e+01;
      alephParameters[2] = 5.04114e-11;
      alephParameters[3] = 2.12543e+00;
      alephParameters[4] = 4.88663e+00;
    }
    fgDefaultPID->GetTPCResponse().SetBetheBlochParameters(alephParameters[0],alephParameters[1],alephParameters[2], alephParameters[3],alephParameters[4]);
    fgDefaultPID->GetTPCResponse().SetSigma(3.79301e-03, 2.21280e+04);

  }
  if(fgLogLevel){
    printf("Error - You are using the default PID: You should use the PID coming from the tender\n");
    printf("Error - Arrrrrrrrr...\n");
    printf("Error - Please rethink your program logic. Using default PID is really dangerous\n");
    printf("Error - TOF PID is adapted to Monte Carlo\n");
  }
  return fgDefaultPID;
}


//__________________________________________
void AliHFEtools::DestroyDefaultPID(){
  //
  // Destroy default PID object if existing
  //
  if(fgDefaultPID) delete fgDefaultPID;
  fgDefaultPID = NULL;
}

//__________________________________________
Int_t AliHFEtools::GetPdg(const AliVParticle *track){
  // 
  // Get MC PDG code (only MC particles supported)
  //
  Int_t pdg = 0;
  if(!TString(track->IsA()->GetName()).CompareTo("AliMCParticle")){
    const AliMCParticle *mctrack = dynamic_cast<const AliMCParticle *>(track);
    pdg = mctrack ? mctrack->Particle()->GetPdgCode() : 0;
  } else if(!TString(track->IsA()->GetName()).CompareTo("AliAODMCParticle")){
    const AliAODMCParticle *aodmctrack = dynamic_cast<const AliAODMCParticle *>(track);
    pdg = aodmctrack ? aodmctrack->GetPdgCode() : 0;
  }
  return pdg;
}

//__________________________________________
Int_t AliHFEtools::PDG2AliPID(Int_t pdg){
  // 
  // Helper function to convert MC PID codes into AliPID codes
  //
  Int_t pid = -1;
  switch(TMath::Abs(pdg)){
    case 11: pid = AliPID::kElectron; break;
    case 13: pid = AliPID::kMuon; break;
    case 211: pid = AliPID::kPion; break;
    case 321: pid = AliPID::kKaon; break;
    case 2212: pid = AliPID::kProton; break;
    default: pid = -1; break;
  };
  return pid;
}

//__________________________________________
TH1D* AliHFEtools::GraphErrorsToHist(TGraphErrors* g, Double_t firstBinWidth, Bool_t exchange, Int_t markerstyle,Int_t markercolor,Float_t markersize)
{
    // Creates a TH1D from TGraph g. The binwidth of the first bin has to
    // specified. The others bins are calculated automatically. Supports also Graphs
    // with non constant x steps. The axis of the Graph can be exchanged if
    // exchange=kTRUE (modifies the Graph).

    TH1D* result = GraphToHist(g,firstBinWidth,exchange, markerstyle,markercolor,markersize);
    if( result == 0) return result;

    //------------------------------------------
    // setup the final hist
    Int_t nBinX = g->GetN();
    Double_t* err = g->GetEY();           // error y is still ok even if exchanged
    for(Int_t i = 0; i < nBinX; i ++){
	result->SetBinError(i + 1, err[i]);
    }
    if(exchange){
        AliHFEtools::ExchangeXYGraph(g);        // undo  what has been done in GraphToHist
	AliHFEtools::ExchangeXYGraphErrors(g);  // now exchange including errors
    }

    return result;
}

//__________________________________________
Bool_t AliHFEtools::ExchangeXYGraph(TGraph* g)
{
    // exchanges x-values and y-values.
    if(g==0) return kFALSE;
    Int_t nbin=g->GetN();
    Double_t x,y;
    for(Int_t i = 0; i < nbin; i ++)
    {
        g->GetPoint(i,x,y);
        g->SetPoint(i,y,x);
    }

    return kTRUE;
}

//__________________________________________
Bool_t AliHFEtools::ExchangeXYGraphErrors(TGraphErrors* g)
{
    // exchanges x-values and y-values and
    // corresponding errors.
    if(g==0) return kFALSE;
    Int_t nbin=g->GetN();
    Double_t x,y;
    Double_t ex,ey;
    for(Int_t i = 0; i < nbin; i ++)
    {
        g->GetPoint(i,x,y);
        ex = g->GetErrorX(i);
        ey = g->GetErrorY(i);
        g->SetPoint(i,y,x);
        g->SetPointError(i,ey,ex);
    }

    return kTRUE;

}

//__________________________________________
TH1D* AliHFEtools::GraphToHist(TGraph* g, Double_t firstBinWidth, Bool_t exchange, Int_t markerstyle,Int_t markercolor,Float_t markersize)
{
    // Creates a TH1D from TGraph g. The binwidth of the first bin has to
    // specified. The others bins are calculated automatically. Supports also Graphs
    // with non constant x steps. The axis of the Graph can be exchanged if
    // exchange=kTRUE (modifies the Graph).


    TH1D* result = 0;
    if(g == 0)              return result;
    if(firstBinWidth == -1) return result;
    TString myname="";
    myname = g->GetName();
    myname += "_graph";
    if(exchange) AliHFEtools::ExchangeXYGraph(g);

    Int_t nBinX = g->GetN();
    Double_t* x = g->GetX();
    Double_t* y = g->GetY();

    if(nBinX < 1) return result;

    //------------------------------------------
    // create the Matrix for the equation system
    // and init the values

    Int_t nDim = nBinX - 1;
    TMatrixD a(nDim,nDim);
    TMatrixD b(nDim,1);

    Double_t* aA = a.GetMatrixArray();
    Double_t* aB = b.GetMatrixArray();
    memset(aA,0,nDim * nDim * sizeof(Double_t));
    memset(aB,0,nDim * sizeof(Double_t));
    //------------------------------------------

    //------------------------------------------
    // setup equation system
    // width for 1st bin is given therefore
    // we shift bin parameter (column) by one to the left
    // to reduce the matrix size

    Double_t* xAxis = new Double_t [nBinX + 1];
    Double_t* binW  = new Double_t [nBinX ];
    binW[0] = firstBinWidth;

    aB[0] = x[1] - x[0]  - 0.5 * binW[0];
    aA[0] = 0.5;

    for(Int_t col = 1; col < nDim ; col ++)
    {
	Int_t row = col;
	aB[col] = x[col + 1] - x[ col ];
	aA[row * nDim + col - 1 ] = 0.5;
	aA[row * nDim + col     ] = 0.5;
    }
    //------------------------------------------

    //------------------------------------------
    // solve the equations
    a.Invert();
    TMatrixD c = a * b;
    //------------------------------------------

    //------------------------------------------
    // calculate the bin boundaries
    xAxis[0] = x[0] - 0.5 * binW[0];
    memcpy(&binW[1],c.GetMatrixArray(),nDim * sizeof(Double_t));
    for(Int_t col = 0; col < nBinX ; col ++) {
	xAxis[col + 1] = x[col] + 0.5 * binW[col];
    }
    //------------------------------------------

    //------------------------------------------
    // setup the final hist
    result = new TH1D(myname.Data(),myname.Data(),nBinX, xAxis);
    for(Int_t i = 0; i < nBinX; i ++){
	result->SetBinContent(i + 1, y[i]);
    }
    result->SetMarkerColor(markercolor);
    result->SetMarkerStyle(markerstyle);
    result->SetMarkerSize(markersize);
    //------------------------------------------

    delete [] xAxis;
    delete [] binW;


    return result;
}
Commit	Line	Data
70da6c5a	1	/**************************************************************************
	2	* Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
	3	* *
	4	* Author: The ALICE Off-line Project. *
	5	* Contributors are mentioned in the code where appropriate. *
	6	* *
	7	* Permission to use, copy, modify and distribute this software and its *
	8	* documentation strictly for non-commercial purposes is hereby granted *
	9	* without fee, provided that the above copyright notice appears in all *
	10	* copies and that both the copyright notice and this permission notice *
	11	* appear in the supporting documentation. The authors make no claims *
	12	* about the suitability of this software for any purpose. It is *
	13	* provided "as is" without express or implied warranty. *
	14	**************************************************************************/
	15	//
	16	// Toolkit containing various usefull things
	17	// Usable everywhere in the hfe software package
	18	// For more information see the cxx file
	19	//
	20	// Authors
	21	// All authors of the HFE group
	22	//
	23	#include <TMath.h>
	24	#include <TParticle.h>
	25	#include "TH1.h"
a8ef1999	26	#include "TH1D.h"
70da6c5a	27	#include "TH2.h"
a8ef1999	28	#include "TGraph.h"
a8ef1999	29	#include "TGraphErrors.h"
70da6c5a	30	#include "THnSparse.h"
70da6c5a	31	#include "TAxis.h"
a8ef1999	32	#include "TMath.h"
a8ef1999	33	#include "TString.h"
70da6c5a	34
70da6c5a	35	#include "AliAODMCParticle.h"
3a72645a	36	#include "AliAODpidUtil.h"
faee3b18	37	#include "AliESDpid.h"
70da6c5a	38	#include "AliLog.h"
3a72645a	39	#include "AliTPCPIDResponse.h"
faee3b18	40	#include "AliTOFPIDResponse.h"
70da6c5a	41
	42	#include "AliHFEtools.h"
	43
	44	ClassImp(AliHFEtools)
	45
8c1c76e9	46	AliPIDResponse *AliHFEtools::fgDefaultPID = NULL;
69ac0e6f	47	Int_t AliHFEtools::fgLogLevel = 0;
faee3b18	48
70da6c5a	49	//__________________________________________
	50	AliHFEtools::AliHFEtools():
	51	TObject()
	52	{
	53	}
	54
	55	//__________________________________________
	56	Double_t *AliHFEtools::MakeLinearBinning(Int_t nBins, Double_t ymin, Double_t ymax){
	57	//
	58	// Helper function for linearly binned array
	59	//
	60	Double_t *bins = new Double_t[nBins + 1];
	61	Double_t stepsize = (ymax - ymin) / static_cast<Double_t>(nBins);
	62	bins[0] = ymin;
	63	for(Int_t ibin = 1; ibin <= nBins; ibin++)
	64	bins[ibin] = bins[ibin-1] + stepsize;
	65	return bins;
	66	}
	67
	68	//__________________________________________
	69	Double_t *AliHFEtools::MakeLogarithmicBinning(Int_t nBins, Double_t ymin, Double_t ymax){
	70	//
	71	// Helper function for logartimically binned array
	72	//
	73	Double_t *bins = new Double_t[nBins+1];
	74	bins[0] = ymin;
	75	Double_t factor = TMath::Power(ymax/ymin, 1./nBins);
	76	for(Int_t ibin = 1; ibin <= nBins; ibin++){
	77	bins[ibin] = factor * bins[ibin-1];
	78	}
	79	return bins;
	80	}
	81
	82	//_________________________________________
	83	Bool_t AliHFEtools::BinLogAxis(TObject *o, Int_t dim){
	84
	85	//
	86	// converts the axis (defined by the dimension) of THx or THnSparse
	87	// object to Log scale. Number of bins and bin min and bin max are preserved
	88	//
	89
	90
	91	if(!o){
	92	AliError("Input histogram is null pointer");
	93	return kFALSE;
	94	}
	95
	96	TAxis *axis = 0x0;
	97	if(o->InheritsFrom("TH1")){
bf892a6a	98	TH1 h1 = dynamic_cast<TH1F>(o);
bf892a6a	99	if(h1) axis = h1->GetXaxis();
70da6c5a	100	}
70da6c5a	101	else if(o->InheritsFrom("TH2")){
bf892a6a	102	TH2 h2 = dynamic_cast<TH2F>(o);
	103	if(h2 && 0 == dim){
	104	axis = h2->GetXaxis();
70da6c5a	105	}
bf892a6a	106	else if(h2 && 1 == dim){
bf892a6a	107	axis = h2->GetYaxis();
70da6c5a	108	}
	109	else{
	110	AliError("Only dim = 0 or 1 possible for TH2F");
	111	}
	112	}
	113	else if(o->InheritsFrom("THnSparse")){
bf892a6a	114	THnSparse hs = dynamic_cast<THnSparse>(o);
bf892a6a	115	if(hs) axis = hs->GetAxis(dim);
70da6c5a	116	}
	117	else{
	118	AliError("Type of input object not recognized, please check your code or update this finction");
	119	return kFALSE;
	120	}
	121	if(!axis){
	122	AliError(Form("Axis '%d' could not be identified in the object \n", dim));
	123	return kFALSE;
	124	}
	125
	126	Int_t bins = axis->GetNbins();
	127
	128	Double_t from = axis->GetXmin();
	129	if(from <= 0){
	130	AliError(Form("Log binning not possible for this axis [min = %f]\n", from));
	131	}
	132	Double_t to = axis->GetXmax();
	133	Double_t *newBins = new Double_t[bins+1];
	134	newBins[0] = from;
	135	Double_t factor = TMath::Power(to/from, 1./bins);
	136	for(Int_t i=1; i<=bins; ++i){
	137	newBins[i] = factor * newBins[i-1];
	138	}
	139	axis->Set(bins, newBins);
bf892a6a	140	delete[] newBins;
70da6c5a	141
	142	return kTRUE;
	143	}
	144
	145	//__________________________________________
3a72645a	146	Float_t AliHFEtools::GetRapidity(const TParticle *part){
70da6c5a	147	//
	148	// return rapidity
	149	//
	150	Float_t rapidity;
	151	if(!((part->Energy() - part->Pz())*(part->Energy() + part->Pz())>0)) rapidity=-999;
	152	else rapidity = 0.5*(TMath::Log((part->Energy()+part->Pz()) / (part->Energy()-part->Pz())));
	153	return rapidity;
	154	}
	155
	156	//__________________________________________
3a72645a	157	Float_t AliHFEtools::GetRapidity(const AliAODMCParticle *part){
70da6c5a	158	// return rapidity
	159
	160	Float_t rapidity;
	161	if(!((part->E() - part->Pz())*(part->E() + part->Pz())>0)) rapidity=-999;
	162	else rapidity = 0.5*(TMath::Log((part->E()+part->Pz()) / (part->E()-part->Pz())));
	163	return rapidity;
	164	}
	165
faee3b18	166	//__________________________________________
8c1c76e9	167	AliPIDResponse* AliHFEtools::GetDefaultPID(Bool_t isMC, Bool_t isESD){
faee3b18	168	//
	169	// Get the default PID as singleton instance
	170	//
	171	if(!fgDefaultPID){
8c1c76e9	172
	173	if(isESD) fgDefaultPID = new AliESDpid;
	174	else fgDefaultPID = new AliAODpidUtil;
faee3b18	175	Double_t tres = isMC ? 80. : 130.;
	176	fgDefaultPID->GetTOFResponse().SetTimeResolution(tres);
	177
	178	// TPC Bethe Bloch parameters
	179	Double_t alephParameters[5];
	180	if(isMC){
	181	// simulation
	182	alephParameters[0] = 2.15898e+00/50.;
	183	alephParameters[1] = 1.75295e+01;
	184	alephParameters[2] = 3.40030e-09;
	185	alephParameters[3] = 1.96178e+00;
	186	alephParameters[4] = 3.91720e+00;
	187	} else {
	188	alephParameters[0] = 0.0283086/0.97;
	189	//alephParameters[0] = 0.0283086;
	190	alephParameters[1] = 2.63394e+01;
	191	alephParameters[2] = 5.04114e-11;
	192	alephParameters[3] = 2.12543e+00;
	193	alephParameters[4] = 4.88663e+00;
	194	}
	195	fgDefaultPID->GetTPCResponse().SetBetheBlochParameters(alephParameters[0],alephParameters[1],alephParameters[2], alephParameters[3],alephParameters[4]);
67fe7bd0	196	fgDefaultPID->GetTPCResponse().SetSigma(3.79301e-03, 2.21280e+04);
faee3b18	197
	198	}
	199	if(fgLogLevel){
67fe7bd0	200	printf("Error - You are using the default PID: You should use the PID coming from the tender\n");
	201	printf("Error - Arrrrrrrrr...\n");
	202	printf("Error - Please rethink your program logic. Using default PID is really dangerous\n");
	203	printf("Error - TOF PID is adapted to Monte Carlo\n");
faee3b18	204	}
	205	return fgDefaultPID;
	206	}
	207
3a72645a	208
faee3b18	209	//__________________________________________
	210	void AliHFEtools::DestroyDefaultPID(){
	211	//
	212	// Destroy default PID object if existing
	213	//
	214	if(fgDefaultPID) delete fgDefaultPID;
	215	fgDefaultPID = NULL;
3a72645a	216	}
	217
	218	//__________________________________________
	219	Int_t AliHFEtools::GetPdg(const AliVParticle *track){
	220	//
	221	// Get MC PDG code (only MC particles supported)
	222	//
	223	Int_t pdg = 0;
	224	if(!TString(track->IsA()->GetName()).CompareTo("AliMCParticle")){
	225	const AliMCParticle mctrack = dynamic_cast<const AliMCParticle >(track);
e3ae862b	226	pdg = mctrack ? mctrack->Particle()->GetPdgCode() : 0;
3a72645a	227	} else if(!TString(track->IsA()->GetName()).CompareTo("AliAODMCParticle")){
3a72645a	228	const AliAODMCParticle aodmctrack = dynamic_cast<const AliAODMCParticle >(track);
e3ae862b	229	pdg = aodmctrack ? aodmctrack->GetPdgCode() : 0;
3a72645a	230	}
	231	return pdg;
	232	}
	233
	234	//__________________________________________
	235	Int_t AliHFEtools::PDG2AliPID(Int_t pdg){
	236	//
	237	// Helper function to convert MC PID codes into AliPID codes
	238	//
	239	Int_t pid = -1;
	240	switch(TMath::Abs(pdg)){
	241	case 11: pid = AliPID::kElectron; break;
	242	case 13: pid = AliPID::kMuon; break;
	243	case 211: pid = AliPID::kPion; break;
	244	case 321: pid = AliPID::kKaon; break;
	245	case 2212: pid = AliPID::kProton; break;
	246	default: pid = -1; break;
	247	};
	248	return pid;
faee3b18	249	}
a8ef1999	250
	251	//__________________________________________
	252	TH1D* AliHFEtools::GraphErrorsToHist(TGraphErrors* g, Double_t firstBinWidth, Bool_t exchange, Int_t markerstyle,Int_t markercolor,Float_t markersize)
	253	{
	254	// Creates a TH1D from TGraph g. The binwidth of the first bin has to
	255	// specified. The others bins are calculated automatically. Supports also Graphs
	256	// with non constant x steps. The axis of the Graph can be exchanged if
	257	// exchange=kTRUE (modifies the Graph).
	258
	259	TH1D* result = GraphToHist(g,firstBinWidth,exchange, markerstyle,markercolor,markersize);
	260	if( result == 0) return result;
	261
	262	//------------------------------------------
	263	// setup the final hist
	264	Int_t nBinX = g->GetN();
	265	Double_t* err = g->GetEY(); // error y is still ok even if exchanged
	266	for(Int_t i = 0; i < nBinX; i ++){
	267	result->SetBinError(i + 1, err[i]);
	268	}
	269	if(exchange){
	270	AliHFEtools::ExchangeXYGraph(g); // undo what has been done in GraphToHist
	271	AliHFEtools::ExchangeXYGraphErrors(g); // now exchange including errors
	272	}
	273
	274	return result;
	275	}
	276
	277	//__________________________________________
	278	Bool_t AliHFEtools::ExchangeXYGraph(TGraph* g)
	279	{
	280	// exchanges x-values and y-values.
	281	if(g==0) return kFALSE;
	282	Int_t nbin=g->GetN();
	283	Double_t x,y;
	284	for(Int_t i = 0; i < nbin; i ++)
	285	{
	286	g->GetPoint(i,x,y);
	287	g->SetPoint(i,y,x);
	288	}
	289
	290	return kTRUE;
	291	}
	292
	293	//__________________________________________
	294	Bool_t AliHFEtools::ExchangeXYGraphErrors(TGraphErrors* g)
	295	{
	296	// exchanges x-values and y-values and
	297	// corresponding errors.
	298	if(g==0) return kFALSE;
	299	Int_t nbin=g->GetN();
	300	Double_t x,y;
	301	Double_t ex,ey;
	302	for(Int_t i = 0; i < nbin; i ++)
	303	{
	304	g->GetPoint(i,x,y);
	305	ex = g->GetErrorX(i);
	306	ey = g->GetErrorY(i);
	307	g->SetPoint(i,y,x);
	308	g->SetPointError(i,ey,ex);
	309	}
	310
	311	return kTRUE;
	312
	313	}
314
315	//__________________________________________
316	TH1D* AliHFEtools::GraphToHist(TGraph* g, Double_t firstBinWidth, Bool_t exchange, Int_t markerstyle,Int_t markercolor,Float_t markersize)
317	{
318	// Creates a TH1D from TGraph g. The binwidth of the first bin has to
319	// specified. The others bins are calculated automatically. Supports also Graphs
320	// with non constant x steps. The axis of the Graph can be exchanged if
321	// exchange=kTRUE (modifies the Graph).
322
323
324	TH1D* result = 0;
325	if(g == 0) return result;
326	if(firstBinWidth == -1) return result;
327	TString myname="";
328	myname = g->GetName();
329	myname += "_graph";
330	if(exchange) AliHFEtools::ExchangeXYGraph(g);
331
332	Int_t nBinX = g->GetN();
333	Double_t* x = g->GetX();
334	Double_t* y = g->GetY();
335
336	if(nBinX < 1) return result;
337
338	//------------------------------------------
339	// create the Matrix for the equation system
340	// and init the values
341
342	Int_t nDim = nBinX - 1;
343	TMatrixD a(nDim,nDim);
344	TMatrixD b(nDim,1);
345
346	Double_t* aA = a.GetMatrixArray();
347	Double_t* aB = b.GetMatrixArray();
348	memset(aA,0,nDim * nDim * sizeof(Double_t));
349	memset(aB,0,nDim * sizeof(Double_t));
350	//------------------------------------------
351
352	//------------------------------------------
353	// setup equation system
354	// width for 1st bin is given therefore
355	// we shift bin parameter (column) by one to the left
356	// to reduce the matrix size
357
358	Double_t* xAxis = new Double_t [nBinX + 1];
359	Double_t* binW = new Double_t [nBinX ];
360	binW[0] = firstBinWidth;
361
362	aB[0] = x[1] - x[0] - 0.5 * binW[0];
363	aA[0] = 0.5;
364
365	for(Int_t col = 1; col < nDim ; col ++)
366	{
367	Int_t row = col;
368	aB[col] = x[col + 1] - x[ col ];
369	aA[row * nDim + col - 1 ] = 0.5;
370	aA[row * nDim + col ] = 0.5;
371	}
372	//------------------------------------------
373
374	//------------------------------------------
375	// solve the equations
376	a.Invert();
377	TMatrixD c = a * b;
378	//------------------------------------------
379
380	//------------------------------------------
381	// calculate the bin boundaries
382	xAxis[0] = x[0] - 0.5 * binW[0];
383	memcpy(&binW[1],c.GetMatrixArray(),nDim * sizeof(Double_t));
384	for(Int_t col = 0; col < nBinX ; col ++) {
385	xAxis[col + 1] = x[col] + 0.5 * binW[col];
386	}
387	//------------------------------------------
388
389	//------------------------------------------
390	// setup the final hist
391	result = new TH1D(myname.Data(),myname.Data(),nBinX, xAxis);
392	for(Int_t i = 0; i < nBinX; i ++){
393	result->SetBinContent(i + 1, y[i]);
394	}
395	result->SetMarkerColor(markercolor);
396	result->SetMarkerStyle(markerstyle);
397	result->SetMarkerSize(markersize);
398	//------------------------------------------
399
400	delete [] xAxis;
401	delete [] binW;
402
403
404	return result;
405	}