ErrorFrameTransformer.h

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#ifndef ErrorFrameTransformer_H
#define ErrorFrameTransformer_H

#include "DataFormats/GeometrySurface/interface/Surface.h"
#include "DataFormats/GeometrySurface/interface/LocalError.h"
#include "DataFormats/GeometryCommonDetAlgo/interface/LocalErrorExtended.h"
#include "DataFormats/GeometryCommonDetAlgo/interface/GlobalError.h"
#include "DataFormats/Math/interface/AlgebraicROOTObjects.h"

#include "DataFormats/CLHEP/interface/AlgebraicObjects.h"

struct ErrorFrameTransformer {
  typedef Surface::Scalar Scalar;

  //old version 1
  static GlobalError transform(const LocalError& le, const Surface& surf) {
    // the GlobalError is a sym matrix, initialisation takes only
    // 6 T because GlobalError is stored as a lower triangular matrix.
    Scalar cxx = le.xx();
    Scalar cxy = le.xy();
    Scalar cyy = le.yy();

    Surface::RotationType r = surf.rotation();

    return GlobalError(r.xx() * (r.xx() * cxx + r.yx() * cxy) + r.yx() * (r.xx() * cxy + r.yx() * cyy),
                       r.xx() * (r.xy() * cxx + r.yy() * cxy) + r.yx() * (r.xy() * cxy + r.yy() * cyy),
                       r.xy() * (r.xy() * cxx + r.yy() * cxy) + r.yy() * (r.xy() * cxy + r.yy() * cyy),
                       r.xx() * (r.xz() * cxx + r.yz() * cxy) + r.yx() * (r.xz() * cxy + r.yz() * cyy),
                       r.xy() * (r.xz() * cxx + r.yz() * cxy) + r.yy() * (r.xz() * cxy + r.yz() * cyy),
                       r.xz() * (r.xz() * cxx + r.yz() * cxy) + r.yz() * (r.xz() * cxy + r.yz() * cyy));
  }

  static LocalError transform(const GlobalError& ge, const Surface& surf) {
    Scalar cxx = ge.cxx();
    Scalar cyx = ge.cyx();
    Scalar cyy = ge.cyy();
    Scalar czx = ge.czx();
    Scalar czy = ge.czy();
    Scalar czz = ge.czz();

    Surface::RotationType r = surf.rotation();

    Scalar l11 = r.xx() * (r.xx() * cxx + r.xy() * cyx + r.xz() * czx) +
                 r.xy() * (r.xx() * cyx + r.xy() * cyy + r.xz() * czy) +
                 r.xz() * (r.xx() * czx + r.xy() * czy + r.xz() * czz);
    Scalar l12 = r.yx() * (r.xx() * cxx + r.xy() * cyx + r.xz() * czx) +
                 r.yy() * (r.xx() * cyx + r.xy() * cyy + r.xz() * czy) +
                 r.yz() * (r.xx() * czx + r.xy() * czy + r.xz() * czz);
    Scalar l22 = r.yx() * (r.yx() * cxx + r.yy() * cyx + r.yz() * czx) +
                 r.yy() * (r.yx() * cyx + r.yy() * cyy + r.yz() * czy) +
                 r.yz() * (r.yx() * czx + r.yy() * czy + r.yz() * czz);

    return LocalError(l11, l12, l22);
  }

  //new Jacobian for 6x6 APE in muon code
  static LocalErrorExtended transform46(const GlobalErrorExtended& ge,
                                        const AlgebraicVector& positions,
                                        const AlgebraicVector& directions) {
    const AlgebraicSymMatrix66& as(ge.matrix());

    AlgebraicMatrix46 jacobian46;
    jacobian46[0][0] = 1.;
    jacobian46[0][1] = 0.;
    jacobian46[0][2] = -directions[0];
    jacobian46[0][3] = -positions[1] * directions[0];
    jacobian46[0][4] = positions[0] * directions[0];
    jacobian46[0][5] = -positions[1];

    jacobian46[1][0] = 0.;
    jacobian46[1][1] = 1.;
    jacobian46[1][2] = -directions[1];
    jacobian46[1][3] = -positions[1] * directions[1];
    jacobian46[1][4] = positions[0] * directions[1];
    jacobian46[1][5] = positions[0];

    jacobian46[2][0] = 0.;
    jacobian46[2][1] = 0.;
    jacobian46[2][2] = 0.;
    jacobian46[2][3] = -directions[1] * directions[0];
    jacobian46[2][4] = 1. + directions[0] * directions[0];
    jacobian46[2][5] = -directions[1];

    jacobian46[3][0] = 0.;
    jacobian46[3][1] = 0.;
    jacobian46[3][2] = 0.;
    jacobian46[3][3] = -1. - directions[1] * directions[1];
    jacobian46[3][4] = directions[0] * directions[1];
    jacobian46[3][5] = directions[0];

    AlgebraicSymMatrix44 out = ROOT::Math::Similarity(jacobian46, as);

    LocalErrorExtended newError(out);

    return newError;
  }
};

#endif