LIChannel.cxx

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// Program name: LIChannel.cxx
//                                                                     
// Package: LISummary
//  
// Coded by Jeff Hartnell Oct/2002  
//
// Based on code by: Rob Morse Feb/2002
//                             
// Purpose: To store and calculate the average mean and rms for a 
//          given channel
//                                                                    
// Contact: jeffrey.hartnell@physics.ox.ac.uk   

#include <cmath>

#include "MessageService/MsgService.h"

#include "LISummary/LIChannel.h"

using namespace std;

CVSID("$Id: LIChannel.cxx,v 1.11 2003/11/18 13:51:01 hartnell Exp $");

//......................................................................

LIChannel::LIChannel()
{
  //initialise variables
  fMean=0;
  fNumEntries=0;
  fRms=0;
  fSigma1=0;
  fSigma2=0;
  fSummaryCounter=0;
}
//......................................................................

LIChannel::~LIChannel()
{
  //nothing
}

//......................................................................

Bool_t operator==(LIChannel a, LIChannel b)
{
  return a.GetRawChannelId()==b.GetRawChannelId();
}

//......................................................................

Bool_t operator<(LIChannel a, LIChannel b)
{
  return a.GetRawChannelId()<b.GetRawChannelId();
}

//......................................................................
 
void LIChannel::Clean()
{
  //reset all variables
  fNumEntries=0;
  fMean=0.;
  fRms=0.;
  fSummaryCounter=0;
  fSigma1=0;
  fSigma2=0;
  fChannelId=RawChannelId();//set to default
}

//......................................................................

void LIChannel::SetEntry(Int_t entries, Float_t mean, 
                         Float_t rms)
{
  fNumEntries=entries;
  fMean=static_cast<Double_t>(mean);
  fRms=static_cast<Double_t>(rms);
  fSummaryCounter=1;
}

//......................................................................

Float_t LIChannel::GetRms()
{
  //calcualte the rms from the sum of 
  //1.) the weighted sum of the (sq of the new mean plus the sq of the
  //    new rms)
  //2.) the weighted sum of all the means
  
  //protect against fpe
  if (fNumEntries==0) return fRms;

  //calculate averages
  Double_t avSigma1=fSigma1/fNumEntries;
  Double_t avSigma2Sqd=pow(fSigma2/fNumEntries,2);
  
  //calculate average rms if possible
  if (avSigma1>=avSigma2Sqd){
    fRms=sqrt(avSigma1-avSigma2Sqd);
  }
  else{//would be imaginary
    fRms=0;
    MSG("LIChannel",Msg::kVerbose) 
      << "Zero rms channel (avSigma1="<<avSigma1
      <<" < avSigma2Sqd="<<avSigma2Sqd<<")"
      <<", ent="<<fNumEntries
      <<", fMean="<<fMean
      <<", fRms="<<fRms 
      << endl;
  }
  return static_cast<Float_t>(fRms);
}

//......................................................................

void LIChannel::AddEntry(Int_t entries, Float_t meanInput, 
                         Float_t rmsInput)
{
  //convert to double to preserve precision
  Double_t rms=static_cast<Double_t>(rmsInput);
  Double_t mean=static_cast<Double_t>(meanInput);
  
  MSG("LIChannel",Msg::kVerbose)
    <<" ent="<<entries<<", mean="<<meanInput<<", rms="<<rmsInput
    <<endl;
  
  //protect against fpe
  if(entries>0){   
    //calcuate the sum of the sq of the new mean and the new rms
    //and weight it by the number of new entries
    fSigma1+=entries*(pow(rms,2)+pow(mean,2));
    
    //calculate weighted sum of all the means
    fSigma2+=mean*entries;
    
    //calculate mean by weighting existing mean and new mean
    fMean=fMean*fNumEntries/(fNumEntries+entries)+
      mean*entries/(fNumEntries+entries);
    
    //sum the number of entries in this channel
    fNumEntries+=entries;
    
    //count the number of summaries included
    fSummaryCounter++;
  }
}

//......................................................................

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