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#include <TrackingTools/GsfTools/interface/MultiTrajectoryStateCombiner.h>
Public Member Functions | |
| TrajectoryStateOnSurface | combine (const std::vector< TrajectoryStateOnSurface > &tsos) const |
| MultiTrajectoryStateCombiner () | |
| ~MultiTrajectoryStateCombiner () | |
Given all the components of a mixture, it calculates the mean and covariance matrix of the entire mixture. This combiner class can also be used in the process of transforming a Gaussian mixture into another Gaussian mixture with a smaller number of components. The relevant formulas can be found in R. Fruhwirth, Computer Physics Communications 100 (1997), 1.
Definition at line 15 of file MultiTrajectoryStateCombiner.h.
| MultiTrajectoryStateCombiner::MultiTrajectoryStateCombiner | ( | ) | [inline] |
| MultiTrajectoryStateCombiner::~MultiTrajectoryStateCombiner | ( | ) | [inline] |
| TrajectoryStateOnSurface MultiTrajectoryStateCombiner::combine | ( | const std::vector< TrajectoryStateOnSurface > & | tsos | ) | const |
Definition at line 6 of file MultiTrajectoryStateCombiner.cc.
References diff, it, it1, mean(), s, and weight.
Referenced by BasicMultiTrajectoryState::checkCombinedState().
00006 { 00007 00008 if (tsos.empty()) { 00009 edm::LogError("MultiTrajectoryStateCombiner") 00010 << "Trying to collapse empty set of trajectory states!"; 00011 return TrajectoryStateOnSurface(); 00012 } 00013 00014 double pzSign = tsos.front().localParameters().pzSign(); 00015 for (std::vector<TrajectoryStateOnSurface>::const_iterator it = tsos.begin(); 00016 it != tsos.end(); it++) { 00017 if (it->localParameters().pzSign() != pzSign) { 00018 edm::LogError("MultiTrajectoryStateCombiner") 00019 << "Trying to collapse trajectory states with different signs on p_z!"; 00020 return TrajectoryStateOnSurface(); 00021 } 00022 } 00023 00024 if (tsos.size() == 1) { 00025 return TrajectoryStateOnSurface(tsos.front()); 00026 } 00027 00028 double sumw = 0.; 00029 //int dim = tsos.front().localParameters().vector().num_row(); 00030 AlgebraicVector5 mean; 00031 AlgebraicSymMatrix55 covarPart1, covarPart2; 00032 for (std::vector<TrajectoryStateOnSurface>::const_iterator it1 = tsos.begin(); 00033 it1 != tsos.end(); it1++) { 00034 double weight = it1->weight(); 00035 AlgebraicVector5 param = it1->localParameters().vector(); 00036 sumw += weight; 00037 mean += weight * param; 00038 covarPart1 += weight * it1->localError().matrix(); 00039 for (std::vector<TrajectoryStateOnSurface>::const_iterator it2 = it1 + 1; 00040 it2 != tsos.end(); it2++) { 00041 AlgebraicVector5 diff = param - it2->localParameters().vector(); 00042 AlgebraicSymMatrix11 s = AlgebraicMatrixID(); //stupid trick to make CLHEP work decently 00043 covarPart2 += weight * it2->weight() * 00044 ROOT::Math::Similarity(AlgebraicMatrix51(diff.Array(), 5), s); 00045 //FIXME: we can surely write this thing in a better way 00046 } 00047 } 00048 double sumwI = 1.0/sumw; 00049 mean *= sumwI; 00050 covarPart1 *= sumwI; covarPart2 *= (sumwI*sumwI); 00051 AlgebraicSymMatrix55 covar = covarPart1 + covarPart2; 00052 00053 return TrajectoryStateOnSurface(LocalTrajectoryParameters(mean, pzSign), 00054 LocalTrajectoryError(covar), 00055 tsos.front().surface(), 00056 &(tsos.front().globalParameters().magneticField()), 00057 tsos.front().surfaceSide(), 00058 sumw); 00059 }
1.5.4