SZLine.h

/**************************************************************************
 * basf2 (Belle II Analysis Software Framework)                           *
 * Author: The Belle II Collaboration                                     *
 *                                                                        *
 * See git log for contributors and copyright holders.                    *
 * This file is licensed under LGPL-3.0, see LICENSE.md.                  *
 **************************************************************************/
#pragma once
 
#include <tracking/trackingUtilities/geometry/SZParameters.h>
#include <tracking/trackingUtilities/numerics/Quadratic.h>
 
#include <Math/Vector2D.h>
 
namespace Belle2 {
  namespace TrackingUtilities {

    class SZLine {
 
    public:
      SZLine()
        : m_tanLambda(NAN)
        , m_z0(NAN)
      {
      }

      SZLine(double tanLambda, double z0)
        : m_tanLambda(tanLambda)
        , m_z0(z0)
      {
      }

      explicit SZLine(const SZParameters& szParameters)
        : m_tanLambda(szParameters(ESZParameter::c_TanL))
        , m_z0(szParameters(ESZParameter::c_Z0))
      {
      }
 
    public:
      double tanLambda() const
      {
        return m_tanLambda;
      }

      double slope() const
      {
        return m_tanLambda;
      }

      double inverseSlope() const
      {
        return 1 / tanLambda();
      }

      double theta() const
      {
        return m_tanLambda;
      }

      void setTanLambda(double tanLambda)
      {
        m_tanLambda = tanLambda;
      }

      double z0() const
      {
        return m_z0;
      }

      double intercept() const
      {
        return m_z0;
      }

      void setZ0(double z0)
      {
        m_z0 = z0;
      }

      SZParameters szParameters() const
      {
        using namespace NSZParameterIndices;
        SZParameters result;
        result(c_TanL) = tanLambda();
        result(c_Z0) = z0();
        return result;
      }

      double zero() const
      {
        return -intercept() / slope();
      }

      double map(double s) const
      {
        return tanLambda() * s + z0();
      }

      double operator()(double s) const
      {
        return map(s);
      }

      double inverseMap(double z) const
      {
        return (z - z0()) / tanLambda();
      }
 
    public:
      void invalidate()
      {
        setZ0(NAN);
        setTanLambda(NAN);
      }

      bool isInvalid() const
      {
        return not std::isfinite(tanLambda()) or not std::isfinite(z0());
      }

      void reverse()
      {
        m_tanLambda = -m_tanLambda;
      }

      SZLine reversed() const
      {
        return SZLine(-tanLambda(), z0());
      }
 
    public:
      double distance(const ROOT::Math::XYVector& szPoint) const
      {
        return distance(szPoint.X(), szPoint.Y());
      }

      double distance(double s, double z) const
      {
        return (map(s) - z) / hypot2(1, tanLambda());
      }

      ROOT::Math::XYVector intersection(const SZLine& szLine) const;

      void passiveMoveBy(const ROOT::Math::XYVector& bySZ)
      {
        passiveMoveBy(bySZ.X(), bySZ.Y());
      }

      void passiveMoveBy(double s, double z)
      {
        m_z0 = map(s) - z;
      }

      SZLine passiveMovedBy(const ROOT::Math::XYVector& bySZ) const
      {
        return passiveMovedBy(bySZ.X(), bySZ.Y());
      }

      SZLine passiveMovedBy(double s, double z) const
      {
        return SZLine(tanLambda(), map(s) - z);
      }

      static SZJacobian passiveMoveByJacobian(const ROOT::Math::XYVector& bySZ)
      {
        using namespace NSZParameterIndices;
        SZJacobian result = SZUtil::identity();
        result(c_Z0, c_TanL) = bySZ.X();
        return result;
      }
 
    private:
      double m_tanLambda;

      double m_z0;
 
    };
  }
}