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/data/refman/pasoursint/CMSSW_5_3_9_patch3/src/TrackingTools/KalmanUpdators/src/KFStripUpdator.cc

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00001 #include "TrackingTools/KalmanUpdators/interface/KFStripUpdator.h"
00002 #include "TrackingTools/KalmanUpdators/interface/StripMeasurementTransformator.h"
00003 #include "DataFormats/Math/interface/invertPosDefMatrix.h"
00004 
00005 
00006 TrajectoryStateOnSurface 
00007 KFStripUpdator::update(const TSOS& aTsos, const TransientTrackingRecHit& aHit) const {
00008 
00009   double pzSign = aTsos.localParameters().pzSign();
00010 
00011   StripMeasurementTransformator myTrafo(aTsos, aHit);
00012 
00013   AlgebraicMatrix25 H(myTrafo.projectionMatrix());
00014   AlgebraicVector2 m(myTrafo.hitParameters());
00015   AlgebraicVector5 x(myTrafo.trajectoryParameters());
00016   AlgebraicVector2 px(myTrafo.projectedTrajectoryParameters());
00017   //  AlgebraicVector px = H*x;
00018   
00019   AlgebraicSymMatrix22 V(myTrafo.hitError());
00020   const AlgebraicSymMatrix55 &C = myTrafo.trajectoryError();
00021   AlgebraicSymMatrix22 pC(myTrafo.projectedTrajectoryError());
00022   //  AlgebraicSymMatrix pC = C.similarity(H);
00023 
00024   AlgebraicSymMatrix22 R(V + pC);
00025   //int ierr; R.invert(ierr); // if (ierr != 0) throw exception;
00026   invertPosDefMatrix(R);
00027   
00028   // Compute Kalman gain matrix
00029   //  AlgebraicMatrix Hm2l(myTrafo.measurement2LocalProj());
00030   AlgebraicMatrix52 K(C * ROOT::Math::Transpose(H) * R);
00031 
00032   // Compute local filtered state vector
00033   AlgebraicVector5 fsv(x + K * (m - px));
00034 
00035   // Compute covariance matrix of local filtered state vector
00036   AlgebraicMatrix55 I = AlgebraicMatrixID();
00037   AlgebraicMatrix55 M = (I - K * H);
00038   AlgebraicSymMatrix55 fse = ROOT::Math::Similarity(M,C) + ROOT::Math::Similarity(K,V);
00039 
00040   return TSOS( LTP(fsv, pzSign), LTE(fse), aTsos.surface(),&(aTsos.globalParameters().magneticField()));  
00041 }
00042 
00043 
00044 
00045