/data/refman/pasoursint/CMSSW_6_1_2_SLHC4_patch1/src/RecoTracker/TkMSParametrization/src/MSLayersAtAngle.cc

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#include "MSLayersAtAngle.h"

#include "RecoTracker/TkMSParametrization/interface/PixelRecoLineRZ.h"
using namespace std;

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

//------------------------------------------------------------------------------
MSLayersAtAngle::MSLayersAtAngle(const vector<MSLayer> & layers)
  : theLayers(layers)
{ sort(theLayers.begin(), theLayers.end()); }
//------------------------------------------------------------------------------
const MSLayer * MSLayersAtAngle::findLayer(const MSLayer & layer) const
{
  vector<MSLayer>::const_iterator it =
     find(theLayers.begin(), theLayers.end(), layer);
  return it==theLayers.end() ? 0 : &(*it);  
}

//------------------------------------------------------------------------------
void MSLayersAtAngle::update(const MSLayer & layer)
{
  vector<MSLayer>::iterator it = find(theLayers.begin(),theLayers.end(),layer); 
  if (it == theLayers.end()) {
    theLayers.push_back(layer);
    sort(theLayers.begin(), theLayers.end()); 
  } else {
    *it = layer;
  }
}

//------------------------------------------------------------------------------
float MSLayersAtAngle::sumX0D(
    const PixelRecoPointRZ & pointI,
    const PixelRecoPointRZ & pointO,
    float tip) const
{
  LayerItr iO = findLayer(pointO, theLayers.begin(), theLayers.end());
//  cout << "outer Layer: "<<*iO<<endl;
  LayerItr iI = findLayer(pointI, theLayers.begin(), iO);
//  cout << "inner Layer: "<<*iI<<endl;

  return sqrt(sum2RmRn(iI,iO, pointO.r(),
                              PixelRecoLineRZ(pointI, pointO, tip)));
}
//------------------------------------------------------------------------------
float MSLayersAtAngle::sumX0D(
    const PixelRecoPointRZ & pointI,
    const PixelRecoPointRZ & pointM,
    const PixelRecoPointRZ & pointO,
    float tip) const
{
  LayerItr iO = findLayer(pointO, theLayers.begin(), theLayers.end());
  LayerItr iI = findLayer(pointI, theLayers.begin(), iO);
  LayerItr iM = findLayer(pointM, iI, iO);

  float drOI = pointO.r() - pointI.r();
  float drMO = pointO.r() - pointM.r();
  float drMI = pointM.r() - pointI.r();

  PixelRecoLineRZ line(pointI, pointO, tip);
  float sum2I = sum2RmRn(iI+1, iM, pointI.r(), line);
  float sum2O = sum2RmRn(iM, iO, pointO.r(), line);

  return sqrt( sum2I* sqr(drMO) + sum2O*sqr(drMI) )/drOI;
}

//------------------------------------------------------------------------------
float MSLayersAtAngle::sum2RmRn(
    MSLayersAtAngle::LayerItr i1,
    MSLayersAtAngle::LayerItr i2,
    float rTarget,
    const PixelRecoLineRZ & line) const
{
  float sum2 = 0.f;
  float cotTh = line.cotLine();
  for (LayerItr it = i1; it < i2; it++) {
    pair<PixelRecoPointRZ,bool> cross = it->crossing(line);
    if (cross.second) {
      float x0 = it->x0(cotTh);
      float dr = rTarget-cross.first.r();
      if (x0 > 1.e-5f) dr *= 1.f+0.038f*std::log(x0); 
      sum2 += x0*dr*dr;
    } 
//  cout << *it << " crossing: "<<cross.second<<endl;
  }
  return sum2;
}
//------------------------------------------------------------------------------
MSLayersAtAngle::LayerItr MSLayersAtAngle::findLayer(
    const PixelRecoPointRZ & point,
    MSLayersAtAngle::LayerItr ibeg,
    MSLayersAtAngle::LayerItr iend) const
{
  const float BIG=99999.f;
  const float EPSILON = 1.e-4f;
  LayerItr theIt = ibeg; float dist = BIG;
  for (LayerItr it = ibeg; it < iend; it++) {
    float d = it->distance(point);
    if (d < dist) {
      if (d < EPSILON) return it; 
      dist = d;
      theIt = it;
    }
  }
  return theIt;
}

//------------------------------------------------------------------------------
void MSLayersAtAngle::print() const 
{
  for (LayerItr it = theLayers.begin(); it != theLayers.end(); it++) 
    cout <<*it<<endl;
}