MSLayersKeeperX0AtEta.cc

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#include "MSLayersKeeperX0AtEta.h"
#include "MultipleScatteringX0Data.h"
#include "MultipleScatteringGeometry.h"
#include <algorithm>
#include "DataFormats/Math/interface/approx_log.h"

using namespace std;

namespace {
  template <class T>
  inline T sqr(T t) {
    return t * t;
  }
  // float unsafe_asinhf(float x) { return std::abs(x)>10.f ? std::copysign(3.f,x) : unsafe_logf<3>(x+std::sqrt(1.f+x*x)); }
  inline float unsafe_asinhf(float x) { return unsafe_logf<3>(x + std::sqrt(1.f + x * x)); }
}  // namespace

//------------------------------------------------------------------------------
const MSLayersAtAngle& MSLayersKeeperX0AtEta::layers(float cotTheta) const {
  float eta = unsafe_asinhf(cotTheta);
  return theLayersData[idxBin(eta)];
}

//------------------------------------------------------------------------------
float MSLayersKeeperX0AtEta::eta(int idxBin) const { return (idxBin + 0.5 - theHalfNBins) * theDeltaEta; }

//------------------------------------------------------------------------------
int MSLayersKeeperX0AtEta::idxBin(float eta) const {
  float ieta = eta / theDeltaEta;
  if (std::abs(ieta) >= theHalfNBins - 1.e-3)
    return (eta > 0) ? max(2 * theHalfNBins - 1, 0) : 0;
  else
    return int(ieta + theHalfNBins);
}

//------------------------------------------------------------------------------
MSLayersKeeperX0AtEta::MSLayersKeeperX0AtEta(const GeometricSearchTracker& tracker, const MagneticField& bfield) {
  const float BIG = 99999.;

  // set size from data file
  MultipleScatteringX0Data msX0data;
  theHalfNBins = msX0data.nBinsEta();
  float etaMax = msX0data.maxEta();
  theDeltaEta = (theHalfNBins != 0) ? etaMax / theHalfNBins : BIG;

  theLayersData = vector<MSLayersAtAngle>(max(2 * theHalfNBins, 1));
  MultipleScatteringGeometry layout(tracker);
  for (int idxbin = 0; idxbin < 2 * theHalfNBins; idxbin++) {
    float etaValue = eta(idxbin);
    float cotTheta = sinh(etaValue);

    vector<MSLayer> layers = layout.detLayers(etaValue, 0, bfield);
    vector<MSLayer> tmplay = layout.otherLayers(etaValue);
    layers.insert(layers.end(), tmplay.begin(), tmplay.end());
    sort(layers.begin(), layers.end());
    setX0(layers, etaValue, msX0data);
    theLayersData[idxbin] = MSLayersAtAngle(layers);
    PixelRecoPointRZ zero(0., 0.);
    PixelRecoLineRZ line(zero, cotTheta);
    vector<MSLayer>::iterator it;
    for (it = layers.begin(); it != layers.end(); it++) {
      float x0 = getDataX0(*it).x0;
      float sumX0D = theLayersData[idxbin].sumX0D(zero, it->crossing(line).first);
      setDataX0(*it, DataX0(x0, sumX0D, cotTheta));
      theLayersData[idxbin].update(*it);
    }
  }

  // add layers not seen from nominal vertex but crossed if
  // vertex seperated from nominal by less than 3 sigma
  for (int idxbin = 0; idxbin < 2 * theHalfNBins; idxbin++) {
    float etaValue = eta(idxbin);
    for (int isign = -1; isign <= 1; isign += 2) {
      float z = isign * 15.9;  //3 sigma from zero
      const MSLayersAtAngle& layersAtAngle = theLayersData[idxbin];
      vector<MSLayer> candidates = layout.detLayers(etaValue, z, bfield);
      vector<MSLayer>::iterator it;
      for (it = candidates.begin(); it != candidates.end(); it++) {
        if (layersAtAngle.findLayer(*it))
          continue;
        const MSLayer* found = nullptr;
        int bin = idxbin;
        while (!found) {
          bin--;
          if (bin < 0)
            break;
          found = theLayersData[bin].findLayer(*it);
        }
        bin = idxbin;
        while (!found) {
          bin++;
          if (bin > 2 * theHalfNBins - 1)
            break;
          found = theLayersData[bin].findLayer(*it);
        }
        if (found)
          theLayersData[idxbin].update(*found);
      }
    }
  }

  // cout << "LAYERS, size=: "<<theLayersData.size()<< endl;
  /*
  for (int idxbin = 0; idxbin <= theHalfNBins; idxbin+=25) {
    float etaValue = eta(idxbin);
    const MSLayersAtAngle & layers= theLayersData[idxbin];
    cout << "ETA: "<< etaValue <<" (bin:"<<idxbin<<") #layers:"
         <<layers.size()<<endl;
    layers.print();
  }
  for (int idxbin = 2*theHalfNBins-1; idxbin > theHalfNBins; idxbin-=25) {
    float etaValue = eta(idxbin);
    const MSLayersAtAngle & layers= theLayersData[idxbin];
    cout << "ETA: "<< etaValue <<" (bin:"<<idxbin<<") #layers:"
         <<layers.size()<<endl;
    layers.print();
  }
*/
}

//------------------------------------------------------------------------------
void MSLayersKeeperX0AtEta::setX0(vector<MSLayer>& layers, float eta, const SumX0AtEtaDataProvider& sumX0) {
  const float BIG = 99999.;
  float cotTheta = sinh(eta);
  float sinTheta = 1 / sqrt(1 + sqr(cotTheta));
  float cosTheta = cotTheta * sinTheta;

  float sumX0atAngleLast = 0.;
  vector<MSLayer>::iterator il;
  for (il = layers.begin(); il != layers.end(); il++) {
    PixelRecoLineRZ line(PixelRecoPointRZ(0., 0.), cotTheta);
    float rL = (*il).crossing(line).first.r();
    float rN = (il + 1 != layers.end()) ? (il + 1)->crossing(line).first.r() : BIG;
    float rBound = (rL + rN) / 2.;
    float sumX0atAngle = sumX0.sumX0atEta(eta, rBound);

    float dX0 = (il->face() == GeomDetEnumerators::barrel) ? (sumX0atAngle - sumX0atAngleLast) * sinTheta
                                                           : (sumX0atAngle - sumX0atAngleLast) * fabs(cosTheta);

    setDataX0(*il, DataX0(dX0, 0, cotTheta));
    sumX0atAngleLast = sumX0atAngle;
  }
}

//------------------------------------------------------------------------------
MSLayersKeeperX0AtEta::~MSLayersKeeperX0AtEta() = default;