/data/refman/pasoursint/CMSSW_5_2_7_hltpatch2/src/RecoTracker/TkMSParametrization/src/MultipleScatteringParametrisation.cc

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#include <vector>
#include "RecoTracker/TkMSParametrization/interface/MultipleScatteringParametrisation.h"
#include "TrackingTools/DetLayers/interface/DetLayer.h"
#include "RecoTracker/TkMSParametrization/interface/PixelRecoPointRZ.h"
#include "RecoTracker/TkMSParametrization/interface/PixelRecoLineRZ.h"


template <class T> inline T sqr( T t) {return t*t;}

#include "RecoTracker/TkMSParametrization/interface/MSLayersKeeper.h"
#include "RecoTracker/TkMSParametrization/interface/MSLayersKeeperX0AtEta.h"
#include "RecoTracker/TkMSParametrization/interface/MSLayersKeeperX0Averaged.h"
#include "RecoTracker/TkMSParametrization/interface/MSLayersKeeperX0DetLayer.h"
#include "RecoTracker/TkMSParametrization/interface/MSLayersAtAngle.h"

//#include "RecoTracker/TkMSParametrization/interface/PixelRecoUtilities.h"

#include<iostream>

using namespace std;

const float MultipleScatteringParametrisation::x0ToSigma = 0.0136f;

//using namespace PixelRecoUtilities;
//----------------------------------------------------------------------
MultipleScatteringParametrisation::
MultipleScatteringParametrisation( const DetLayer* layer,const edm::EventSetup &iSetup, X0Source x0Source)
 
{
  switch (x0Source) {
  case useX0AtEta: { 
    static MSLayersKeeperX0AtEta x0AtEta; 
    theLayerKeeper = &x0AtEta;
    break;
  }
  case useX0DataAveraged: {
    static MSLayersKeeperX0Averaged x0Averaged;
    theLayerKeeper = &x0Averaged;
    break;
  }

  case useDetLayer: {
    static MSLayersKeeperX0DetLayer x0DetLayer;
    theLayerKeeper = &x0DetLayer;
    break;
  }
  default:
    //FIXME should throw or similar
    cout << "** MultipleScatteringParametrisation ** wrong x0Source"<<endl;
    return;
  }
  theLayerKeeper->init(iSetup);
  if (!layer) return;
  theLayer = theLayerKeeper->layer(layer);
} 

//----------------------------------------------------------------------
float MultipleScatteringParametrisation::operator()(
    float pT, float cotTheta, float tip) const
{
  float sumX0D = theLayer.sumX0D(cotTheta); 
  return x0ToSigma * sumX0D /pT;
}

//----------------------------------------------------------------------
float MultipleScatteringParametrisation::operator()(
  float pT, float cotTheta, const PixelRecoPointRZ & pointI, float tip) const
{

  PixelRecoLineRZ lineIO(pointI, cotTheta, tip);
  PixelRecoPointRZ pointO = theLayer.crossing(lineIO).first;

  const MSLayersAtAngle & layersAtEta = theLayerKeeper->layers(cotTheta);
  
  float sumX0D = layersAtEta.sumX0D(pointI, pointO);
  return x0ToSigma * sumX0D /pT;
}

//----------------------------------------------------------------------
float MultipleScatteringParametrisation::operator()(
    float pT,
    const PixelRecoPointRZ & pointI,
    const PixelRecoPointRZ & pointO,
    Consecutive consecutive,
    float tip) const
{   


  PixelRecoLineRZ lineIO(pointI, pointO, tip);
  PixelRecoPointRZ pointM = theLayer.crossing(lineIO).first;
  float cotTheta = lineIO.cotLine();

  if (consecutive==useConsecutive) {
    float dist = fabs(  (pointO.r()-pointM.r())
                      * (pointM.r()-pointI.r())
                      / (pointO.r()-pointI.r()) );
    return  x0ToSigma * sqrt(theLayer.x0(cotTheta)) * dist /pT;
  } else {
    const MSLayersAtAngle & layersAtEta = theLayerKeeper->layers(cotTheta);
    float sumX0D = layersAtEta.sumX0D(pointI, pointM, pointO);
    return x0ToSigma * sumX0D /pT;
  }
}