ThirdHitPredictionFromInvParabola.cc

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#include "ThirdHitPredictionFromInvParabola.h"

#include <cmath>
#include "DataFormats/GeometryVector/interface/GlobalVector.h"
#include "DataFormats/GeometryVector/interface/GlobalPoint.h"

#include "RecoTracker/TkHitPairs/interface/OrderedHitPair.h"
#include "RecoTracker/TkTrackingRegions/interface/TrackingRegion.h"
#include "RecoTracker/TkMSParametrization/interface/PixelRecoUtilities.h"

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

#include "DataFormats/Math/interface/approx_atan2.h"
namespace {
  inline float f_atan2f(float y, float x) { return unsafe_atan2f<7>(y, x); }
  template <typename V>
  inline float f_phi(V v) {
    return f_atan2f(v.y(), v.x());
  }
}  // namespace

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

using namespace std;

ThirdHitPredictionFromInvParabola::ThirdHitPredictionFromInvParabola(
    const GlobalPoint& P1, const GlobalPoint& P2, Scalar ip, Scalar curv, Scalar tolerance)
    : theTolerance(tolerance) {
  init(P1, P2, ip, std::abs(curv));
}

void ThirdHitPredictionFromInvParabola::init(Scalar x1, Scalar y1, Scalar x2, Scalar y2, Scalar ip, Scalar curv) {
  //  GlobalVector aX = GlobalVector( P2.x()-P1.x(), P2.y()-P1.y(), 0.).unit();

  Point2D p1(x1, y1);
  Point2D p2(x2, y2);
  theRotation = Rotation(p1);
  p1 = transform(p1);  // (1./P1.xy().mag(),0);
  p2 = transform(p2);

  u1u2 = p1.x() * p2.x();
  overDu = 1. / (p2.x() - p1.x());
  pv = p1.y() * p2.x() - p2.y() * p1.x();
  dv = p2.y() - p1.y();
  su = p2.x() + p1.x();

  ip = std::abs(ip);
  RangeD ipRange(-ip, ip);

  Scalar ipIntyPlus = ipFromCurvature(0., true);
  Scalar ipCurvPlus = ipFromCurvature(curv, true);
  Scalar ipCurvMinus = ipFromCurvature(curv, false);

  RangeD ipRangePlus(std::min(ipIntyPlus, ipCurvPlus), std::max(ipIntyPlus, ipCurvPlus));
  RangeD ipRangeMinus(std::min(-ipIntyPlus, ipCurvMinus), std::max(-ipIntyPlus, ipCurvMinus));

  theIpRangePlus = ipRangePlus.intersection(ipRange);
  theIpRangeMinus = ipRangeMinus.intersection(ipRange);

  emptyP = theIpRangePlus.empty();
  emptyM = theIpRangeMinus.empty();
}

ThirdHitPredictionFromInvParabola::Range ThirdHitPredictionFromInvParabola::rangeRPhi(Scalar radius,
                                                                                      int icharge) const {
  bool pos = icharge > 0;

  RangeD ip = (pos) ? theIpRangePlus : theIpRangeMinus;

  //  it will vectorize with gcc 4.7 (with -O3 -fno-math-errno)
  // change sign as intersect assume -ip for negative charge...
  Scalar ipv[2] = {(pos) ? ip.min() : -ip.min(), (pos) ? ip.max() : -ip.max()};
  Scalar u[2], v[2];
  for (int i = 0; i != 2; ++i)
    findPointAtCurve(radius, ipv[i], u[i], v[i]);

  //
  Scalar phi1 = f_phi(theRotation.rotateBack(Point2D(u[0], v[0])));
  Scalar phi2 = phi1 + (v[1] - v[0]);

  if (phi2 < phi1)
    std::swap(phi1, phi2);

  if (ip.empty()) {
    Range r1(phi1 * radius - theTolerance, phi1 * radius + theTolerance);
    Range r2(phi2 * radius - theTolerance, phi2 * radius + theTolerance);
    return r1.intersection(r2);  // this range can be empty
  }

  return Range(radius * phi1 - theTolerance, radius * phi2 + theTolerance);
}

ThirdHitPredictionFromInvParabola::Range ThirdHitPredictionFromInvParabola::rangeRPhi(Scalar radius) const {
  auto getRange = [&](Scalar phi1, Scalar phi2, bool empty) -> RangeD {
    if (phi2 < phi1)
      std::swap(phi1, phi2);
    if (empty) {
      RangeD r1(phi1 * radius - theTolerance, phi1 * radius + theTolerance);
      RangeD r2(phi2 * radius - theTolerance, phi2 * radius + theTolerance);
      return r1.intersection(r2);
    }

    return RangeD(radius * phi1 - theTolerance, radius * phi2 + theTolerance);
  };

  //  it will vectorize with gcc 4.7 (with -O3 -fno-math-errno)
  // change sign as intersect assume -ip for negative charge...
  Scalar ipv[4] = {theIpRangePlus.min(), -theIpRangeMinus.min(), theIpRangePlus.max(), -theIpRangeMinus.max()};
  Scalar u[4], v[4];
  for (int i = 0; i < 4; ++i)
    findPointAtCurve(radius, ipv[i], u[i], v[i]);

  //
  auto xr = theRotation.x();
  auto yr = theRotation.y();

  Scalar phi1[2], phi2[2];
  for (int i = 0; i < 2; ++i) {
    auto x = xr[0] * u[i] + yr[0] * v[i];
    auto y = xr[1] * u[i] + yr[1] * v[i];
    phi1[i] = f_atan2f(y, x);
    phi2[i] = phi1[i] + (v[i + 2] - v[i]);
  }

  return getRange(phi1[1], phi2[1], emptyM).sum(getRange(phi1[0], phi2[0], emptyP));
}

/*
ThirdHitPredictionFromInvParabola::Range ThirdHitPredictionFromInvParabola::rangeRPhiSlow(
    Scalar radius, int charge, int nIter) const
{
  Range predRPhi(1.,-1.);

  Scalar invr2 = 1/(radius*radius);
  Scalar u = sqrt(invr2);
  Scalar v = 0.;

  Range ip = (charge > 0) ? theIpRangePlus : theIpRangeMinus;

  for (int i=0; i < nIter; ++i) {
    v = predV(u, charge*ip.min()); 
    Scalar d2 = invr2-sqr(v);
    u = (d2 > 0) ? sqrt(d2) : 0.;
  }
  Point2D  pred_tmp1(u, v);
  Scalar phi1 = transformBack(pred_tmp1).phi(); 
  while ( phi1 >= M_PI) phi1 -= 2*M_PI;
  while ( phi1 < -M_PI) phi1 += 2*M_PI;


  u = sqrt(invr2); 
  v=0;
  for (int i=0; i < nIter; ++i) {
    v = predV(u, ip.max(), charge); 
    Scalar d2 = invr2-sqr(v);
    u = (d2 > 0) ? sqrt(d2) : 0.;
  }
  Point2D  pred_tmp2(u, v);
  Scalar phi2 = transformBack(pred_tmp2).phi(); 
  while ( phi2-phi1 >= M_PI) phi2 -= 2*M_PI;
  while ( phi2-phi1 < -M_PI) phi2 += 2*M_PI;

// check faster alternative, without while(..) it is enough to:
//  phi2 = phi1+radius*(pred_tmp2.v()-pred_tmp1.v()); 

  if (ip.empty()) {
    Range r1(phi1*radius-theTolerance, phi1*radius+theTolerance); 
    Range r2(phi2*radius-theTolerance, phi2*radius+theTolerance); 
    predRPhi = r1.intersection(r2);
  } else {
    Range r(phi1, phi2); 
    r.sort();
    predRPhi= Range(radius*r.min()-theTolerance, radius*r.max()+theTolerance);
  }
  return predRPhi;

}
*/