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#include "TrackingTools/PatternTools/interface/TwoTrackMinimumDistanceLineLine.h"
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#include "TrackingTools/TrajectoryParametrization/interface/GlobalTrajectoryParameters.h"
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#include "DataFormats/GeometryVector/interface/GlobalVector.h"
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#include "FWCore/MessageLogger/interface/MessageLogger.h"
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#include "MagneticField/Engine/interface/MagneticField.h"
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bool TwoTrackMinimumDistanceLineLine::calculate(
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const GlobalTrajectoryParameters & theG,
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const GlobalTrajectoryParameters & theH)
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{
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GlobalPoint gOrig = theG.position();
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GlobalPoint hOrig = theH.position();
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if ( ( ( theH.charge() != 0. || theG.charge() != 0. ) ) &&
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((theG.magneticField().inTesla(gOrig).z() != 0.)||
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(theH.magneticField().inTesla(hOrig).z() != 0.)) )
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{
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edm::LogWarning ("TwoTrackMinimumDistanceLineLine")
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<< "charge of input track is not zero or field non zero"
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<< "\n positions: "<<gOrig<<" , "<<hOrig
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<< "\n Bz fields: "<<theG.magneticField().inTesla(gOrig).z()<<" , "<<theH.magneticField().inTesla(hOrig).z()
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<< "\n charges: "<<theG.charge()<<" , "<<theH.charge();
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return true;
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};
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GlobalVector gVec = theG.momentum();
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const double gMag= theG.momentum().mag(); double gMag2 = gMag*gMag;
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GlobalVector hVec = theH.momentum();
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const double hMag= theH.momentum().mag(); double hMag2 = hMag*hMag;
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if ( gMag == 0. || hMag == 0. )
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{
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edm::LogWarning ("TwoTrackMinimumDistanceLineLine")
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<< "momentum of input trajectory is zero.";
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return true;
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};
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phiG = theG.momentum().phi();
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phiH = theH.momentum().phi();
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double gVec_Dot_hVec = gVec.dot(hVec);
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double norm = gVec_Dot_hVec*gVec_Dot_hVec - gMag2*hMag2;
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if ( norm == 0 )
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{
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edm::LogWarning ("TwoTrackMinimumDistanceLineLine")
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<< "Tracks are parallel.";
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return true;
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}
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GlobalVector posDiff = gOrig - hOrig;
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double tG = (posDiff.dot(gVec) * hMag2 - gVec_Dot_hVec * posDiff.dot(hVec))/ norm;
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double tH = (gVec_Dot_hVec * posDiff.dot(gVec) - posDiff.dot(hVec) * gMag2)/ norm;
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gPos = GlobalPoint ( gOrig + tG * gVec);
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hPos = GlobalPoint ( hOrig + tH * hVec);
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// cout << "TwoTrackMinimumDistanceLineLine "<<gPos<<hPos<<endl;
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pathG = tG * gMag;
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pathH = tH * hMag;
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return false;
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}
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std::pair<GlobalPoint, GlobalPoint> TwoTrackMinimumDistanceLineLine::points() const
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{
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return std::pair<GlobalPoint, GlobalPoint > ( gPos, hPos );
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}
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std::pair<double, double> TwoTrackMinimumDistanceLineLine::pathLength() const
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{
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return std::pair<double, double> ( pathG, pathH);
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}
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