/******************************************************************************
*  $Id: CbmRichRingFitter.cxx,v 1.2 2006/09/13 14:57:15 hoehne Exp $
*
*  Class  : CbmRichRingFitter
*  Description: Empty file, just there to please CINT, DoFit is implemented
*               in the actual algorithm.
*
*  Author : Supriya Das
*  E-mail : S.Das@gsi.de
*
*******************************************************************************
*  $Log: CbmRichRingFitter.cxx,v $
*  Revision 1.2  2006/09/13 14:57:15  hoehne
*  task for calculating Chi2 of ring fit added
*
*  Revision 1.1  2006/01/19 11:33:12  hoehne
*  initial version: base class for RingFitters
*
*
*******************************************************************************/

#include "CbmRichRingFitter.h"


#include "CbmRichRing.h"
#include "CbmRootManager.h"
#include "CbmRichHit.h"

// -----   Protected method CalcChi2   ----------------------------------------
void CbmRichRingFitter::CalcChi2(CbmRichRing* pRing)
{
    
    
    Int_t fNhits=pRing->GetNoOfHits();
    
    if (fNhits < 4) {
      pRing->SetChi2(-1.);
      return;
    }
            
    Double_t Xd2, Yd2;
    Double_t ChiSquare = 0.;
    Double_t Xcenter, Ycenter, Radius;
    
    Radius  = pRing->GetRadius();
    Xcenter = pRing->GetCenterX();
    Ycenter = pRing->GetCenterY();    
    
    for (int i = 0; i < fNhits; i++) {
    
        CbmRichHit *hit = (CbmRichHit*)pRing->GetHit(i);
	
	Xd2 = Xcenter - hit->X();
	Yd2 = Ycenter - hit->Y();
	
	Xd2 *= Xd2;
	Yd2 *= Yd2;
	
	ChiSquare += TMath::Sqrt( Xd2 + Yd2 ) - Radius;
    }
    
    ChiSquare *= ChiSquare;
    
    if (fNhits == 3) cout << " -W- CbmRichRingFitter: division by 0 " << endl;
    fChi2 = ChiSquare / (fNhits - 3);
    
    pRing->SetChi2(fChi2);

}

ClassImp(CbmRichRingFitter)