DmxChiSqrStat.cxx

Go to the documentation of this file.

//$Id: DmxChiSqrStat.cxx,v 1.28 2002/10/03 21:22:48 brebel Exp $
//
//DmxChiSqrStat.cxx
//
//DmxChiSqrStat is a Statistic class returning a Chi^2 statistic
//
//Author:  B. Rebel 6/2000

#include <iostream>
#include "DeMux/DmxChiSqrStat.h"
#include "MessageService/MsgService.h"
#include "MessageService/MsgFormat.h"
#include "DeMux/DmxRMSStat.h"
#include "TMath.h"

ClassImp(DmxChiSqrStat)

//______________________________________________________________________
//CVSID("$Id: DmxChiSqrStat.cxx,v 1.28 2002/10/03 21:22:48 brebel Exp $");

//----------------------------------------------------------------------
DmxChiSqrStat::DmxChiSqrStat() 
{
}

//----------------------------------------------------------------------
DmxChiSqrStat::DmxChiSqrStat(Float_t *SignalW, Float_t *SignalE, Float_t CoG) :
  fChi2(0.),
  fRms(-1.),
  fPredictor(0.)
{

  Float_t sumW = 0.;
  Float_t sumE = 0.;

  //sum up the signal on sides W and E 

  for(Int_t i = 0; i < 192; i++ ){
    sumE += SignalE[i];
    sumW += SignalW[i];
  }
  
  //check to see if we can initialize the predictor as sumE / sumW.  if not
  //set it = 0.
  
  if(sumW > 0.) { fPredictor = sumE / sumW; }
    
  //MSG("DmxHyp", Msg::kInfo) << "predictor\t" << fPredictor << endl;

  //MSG("DmxHyp", Msg::kInfo) << "DmxChiSqrStat calculating goodness of fit" 
  //        << endl << endl;


  //this loop finds the chi^2 statistic for the signal and strip information
  //passed to the constructor.  the statistic is
  //
  //   chi^2 = SUM[ (RW_i - E_i)^2 / (W_i^2 + E_i^2) ]
  //
  //where R is fPredictor and W_i, E_i is the signal for strip i. 

  if( fPredictor > 0. ){
    for(Int_t j = 0; j < 192; j++){
      if(SignalW[j] > 0. || SignalE[j] > 0.){
        fChi2 += (((fPredictor * SignalW[j]) - SignalE[j]) * ((fPredictor * SignalW[j]) - SignalE[j])) / 
          ((SignalW[j] * SignalW[j]) + (SignalE[j] * SignalE[j]));
        //MSG("DmxHyp", Msg::kInfo) <<"strip = " << j << "\tchi^2 = " << fChi2 << "\tpredicter = " 
        //  << fPredictor << "\tW = " << SignalW[j] 
        //  << "\tE = " << SignalE[j] << endl;
      }
    }
  }
  else{ fChi2 = 10000.; }
  //MSG("DmxHyp", Msg::kInfo) << "chi^2 = " << fChi2 <<endl;

  //find the tiebreaker
  DmxRMSStat rms = DmxRMSStat(SignalW, SignalE, CoG);
   
  fRms = rms.GetGoodness();

  return;

}

//-----------------------------------------------------------------------
DmxChiSqrStat::~DmxChiSqrStat()
{
  //MSG("Dmx", Msg::kVerbose) << "deleting DmxChiSqrObject" << endl;
}


//-----------------------------------------------------------------------
Float_t DmxChiSqrStat::GetGoodness() const
{
  
  return fChi2;
}

//-----------------------------------------------------------------------
Float_t DmxChiSqrStat::GetPredictor() const
{
  return fPredictor;
}

//-----------------------------------------------------------------------
//the following method returns the rms of the reconstruction for use
//as a tiebreaker if the chi^2 stat is the same for two signal/strip 
//combinations

Float_t DmxChiSqrStat::GetTieBreaker() const 
{
  return fRms;
}

//------------------------------------------------------------------------
void DmxChiSqrStat::SetPredictor(Float_t predictor)
{
  fPredictor = predictor;
}
 
  
  

---