#include <CSCSegAlgoShowering.h>

Public Types
typedef std::vector< const CSCRecHit2D * >	ChamberHitContainer

Public Member Functions
	CSCSegAlgoShowering (const edm::ParameterSet &ps)
	Constructor. More...

CSCSegment	showerSeg (const CSCChamber *aChamber, const ChamberHitContainer &rechits)

virtual	~CSCSegAlgoShowering ()
	Destructor. More...

Private Member Functions
bool	addHit (const CSCRecHit2D *hit, int layer)

AlgebraicSymMatrix	calculateError (void) const

void	compareProtoSegment (const CSCRecHit2D *h, int layer)

CLHEP::HepMatrix	derivativeMatrix (void) const

void	flipErrors (AlgebraicSymMatrix &) const

bool	hasHitOnLayer (int layer) const

bool	isHitNearSegment (const CSCRecHit2D *h) const
	Utility functions. More...

void	pruneFromResidual ()

void	updateParameters (void)

AlgebraicSymMatrix	weightMatrix (void) const

Private Attributes
float	chi2Max

bool	debug

double	dPhiFineMax

double	dRPhiFineMax

float	maxDPhi

float	maxDTheta

float	maxRatioResidual

int	minHitsPerSegment

const std::string	myName

double	protoChi2

LocalVector	protoDirection

LocalPoint	protoIntercept

ChamberHitContainer	protoSegment

float	protoSlope_u

float	protoSlope_v

float	tanPhiMax

float	tanThetaMax

const CSCChamber *	theChamber

Detailed Description

class CSCSegAlgoShowering

Author: : D. Fortin - UC Riverside by J. Babb - UC Riverside

Handle case where too many hits are reconstructed in the chamber, even after preclustering for normal segment reconstruction to properly handle these. In this case, determine the average local (x,y) for each layer and find the hit closest to that localpoint for that given layer. From these hits, reconstruct a segment. The idea is to give the reconstruction (seeding) a valid starting point for the kalman filter.

Definition at line 24 of file CSCSegAlgoShowering.h.

Member Typedef Documentation

typedef std::vector<const CSCRecHit2D*> CSCSegAlgoShowering::ChamberHitContainer

Definition at line 28 of file CSCSegAlgoShowering.h.

Constructor & Destructor Documentation

CSCSegAlgoShowering::CSCSegAlgoShowering ( const edm::ParameterSet & ps )

explicit

Constructor.

Definition at line 28 of file CSCSegAlgoShowering.cc.

References dPhiFineMax, dRPhiFineMax, edm::ParameterSet::getParameter(), maxDPhi, maxDTheta, maxRatioResidual, tanPhiMax, and tanThetaMax.

                                                                   {
 //  debug                  = ps.getUntrackedParameter<bool>("CSCSegmentDebug");
   dRPhiFineMax           = ps.getParameter<double>("dRPhiFineMax");
   dPhiFineMax            = ps.getParameter<double>("dPhiFineMax");
   tanThetaMax            = ps.getParameter<double>("tanThetaMax");
   tanPhiMax              = ps.getParameter<double>("tanPhiMax");    
   maxRatioResidual       = ps.getParameter<double>("maxRatioResidualPrune");
 //  maxDR                  = ps.getParameter<double>("maxDR");
   maxDTheta              = ps.getParameter<double>("maxDTheta");
   maxDPhi                = ps.getParameter<double>("maxDPhi");
 }

CSCSegAlgoShowering::~CSCSegAlgoShowering ( )

virtual

Destructor.

Definition at line 44 of file CSCSegAlgoShowering.cc.

                                          {
 
 }

Member Function Documentation

bool CSCSegAlgoShowering::addHit	(	const CSCRecHit2D *	hit,
		int	layer
	)

private

Definition at line 301 of file CSCSegAlgoShowering.cc.

References convertSQLiteXML::ok, and protoSegment.

Referenced by compareProtoSegment().

                                                                    {
   
   // Return true if hit was added successfully and then parameters are updated.
   // Return false if there is already a hit on the same layer, or insert failed.
   
   bool ok = true;
   
   // Test that we are not trying to add the same hit again
   for ( ChamberHitContainer::const_iterator it = protoSegment.begin(); it != protoSegment.end(); it++ ) 
     if ( aHit == (*it)  ) return false;
   
   protoSegment.push_back(aHit);
 
   return ok;
 }    

AlgebraicSymMatrix CSCSegAlgoShowering::calculateError ( void ) const

private

Definition at line 517 of file CSCSegAlgoShowering.cc.

References HLT_25ns14e33_v1_cff::A, derivativeMatrix(), query::result, weightMatrix(), and create_public_pileup_plots::weights.

Referenced by showerSeg().

                                                              {
 
   AlgebraicSymMatrix weights = weightMatrix();
   AlgebraicMatrix A = derivativeMatrix();
 
   // (AT W A)^-1
   // from http://www.phys.ufl.edu/~avery/fitting.html, part I
   int ierr;
   AlgebraicSymMatrix result = weights.similarityT(A);
   result.invert(ierr);
 
   // blithely assuming the inverting never fails...
   return result;
 }

void CSCSegAlgoShowering::compareProtoSegment	(	const CSCRecHit2D *	h,
		int	layer
	)

private

Definition at line 433 of file CSCSegAlgoShowering.cc.

References addHit(), convertSQLiteXML::ok, protoChi2, protoDirection, protoIntercept, protoSegment, protoSlope_u, protoSlope_v, and updateParameters().

Referenced by showerSeg().

                                                                              {
   
   // Store old segment first
   double old_protoChi2                  = protoChi2;
   LocalPoint old_protoIntercept         = protoIntercept;
   float old_protoSlope_u                = protoSlope_u;
   float old_protoSlope_v                = protoSlope_v;
   LocalVector old_protoDirection        = protoDirection;
   ChamberHitContainer old_protoSegment  = protoSegment;
  
 
   // Try adding the hit to existing segment, and remove old one existing in same layer
   ChamberHitContainer::iterator it;
   for ( it = protoSegment.begin(); it != protoSegment.end(); ) {
     if ( (*it)->cscDetId().layer() == layer ) {
       it = protoSegment.erase(it);
     } else {
       ++it;
     }
   }
   bool ok = addHit(h, layer);
 
   if (ok) updateParameters();
   
   if ( (protoChi2 > old_protoChi2) || ( !ok ) ) {
     protoChi2       = old_protoChi2;
     protoIntercept  = old_protoIntercept;
     protoSlope_u    = old_protoSlope_u;
     protoSlope_v    = old_protoSlope_v;
     protoDirection  = old_protoDirection;
     protoSegment    = old_protoSegment;
   }
 }

CLHEP::HepMatrix CSCSegAlgoShowering::derivativeMatrix ( void ) const

private

Definition at line 490 of file CSCSegAlgoShowering.cc.

References CSCRecHit2D::cscDetId(), CSCChamber::layer(), CSCDetId::layer(), CSCRecHit2D::localPosition(), makeMuonMisalignmentScenario::matrix, protoSegment, theChamber, GeomDet::toGlobal(), GeomDet::toLocal(), detailsBasic3DVector::z, and PV3DBase< T, PVType, FrameType >::z().

Referenced by calculateError().

                                                            {
 
   ChamberHitContainer::const_iterator it;
   int nhits = protoSegment.size();
   CLHEP::HepMatrix matrix(2*nhits, 4);
   int row = 0;
 
   for(it = protoSegment.begin(); it != protoSegment.end(); ++it) {
 
     const CSCRecHit2D& hit = (**it);
     const CSCLayer* layer = theChamber->layer(hit.cscDetId().layer());
     GlobalPoint gp = layer->toGlobal(hit.localPosition());
     LocalPoint lp = theChamber->toLocal(gp);
     float z = lp.z();
     ++row;
     matrix(row, 1) = 1.;
     matrix(row, 3) = z;
     ++row;
     matrix(row, 2) = 1.;
     matrix(row, 4) = z;
   }
   return matrix;
 }

void CSCSegAlgoShowering::flipErrors ( AlgebraicSymMatrix & a ) const

private

Definition at line 532 of file CSCSegAlgoShowering.cc.

References a.

Referenced by showerSeg().

                                                                   {
 
   // The CSCSegment needs the error matrix re-arranged
 
   AlgebraicSymMatrix hold( a );
 
   // errors on slopes into upper left
   a(1,1) = hold(3,3);
   a(1,2) = hold(3,4);
   a(2,1) = hold(4,3);
   a(2,2) = hold(4,4);
 
   // errors on positions into lower right
   a(3,3) = hold(1,1);
   a(3,4) = hold(1,2);
   a(4,3) = hold(2,1);
   a(4,4) = hold(2,2);
 
   // off-diagonal elements remain unchanged
 
 }

bool CSCSegAlgoShowering::hasHitOnLayer ( int layer ) const

private

bool CSCSegAlgoShowering::isHitNearSegment ( const CSCRecHit2D * h ) const

private

Utility functions.

Definition at line 264 of file CSCSegAlgoShowering.cc.

References CSCRecHit2D::cscDetId(), SiPixelRawToDigiRegional_cfi::deltaPhi, dPhiFineMax, dRPhiFineMax, CSCChamber::layer(), CSCDetId::layer(), CSCRecHit2D::localPosition(), M_PI, PV3DBase< T, PVType, FrameType >::phi(), protoIntercept, protoSlope_u, protoSlope_v, dttmaxenums::R, mathSSE::sqrt(), theChamber, GeomDet::toGlobal(), GeomDet::toLocal(), PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), detailsBasic3DVector::z, and PV3DBase< T, PVType, FrameType >::z().

Referenced by showerSeg().

                                                                         {
 
   const CSCLayer* layer = theChamber->layer(hit->cscDetId().layer());
 
   // hit phi position in global coordinates
   GlobalPoint Hgp = layer->toGlobal(hit->localPosition());
   double Hphi = Hgp.phi();                                
   if (Hphi < 0.) Hphi += 2.*M_PI;
   LocalPoint Hlp = theChamber->toLocal(Hgp);
   double z = Hlp.z();  
 
   double LocalX = protoIntercept.x() + protoSlope_u * z;
   double LocalY = protoIntercept.y() + protoSlope_v * z;
   LocalPoint Slp(LocalX, LocalY, z);
   GlobalPoint Sgp = theChamber->toGlobal(Slp); 
   double Sphi = Sgp.phi();
   if (Sphi < 0.) Sphi += 2.*M_PI;
   double R = sqrt(Sgp.x()*Sgp.x() + Sgp.y()*Sgp.y());
   
   double deltaPhi = Sphi - Hphi;
   if (deltaPhi >  2.*M_PI) deltaPhi -= 2.*M_PI;
   if (deltaPhi < -2.*M_PI) deltaPhi += 2.*M_PI;
   if (deltaPhi < 0.) deltaPhi = -deltaPhi; 
 
   double RdeltaPhi = R * deltaPhi;
 
   if (RdeltaPhi < dRPhiFineMax && deltaPhi < dPhiFineMax ) return true;
 
   return false;
 }

void CSCSegAlgoShowering::pruneFromResidual ( )

private

Definition at line 555 of file CSCSegAlgoShowering.cc.

References CSCRecHit2D::cscDetId(), j, CSCChamber::layer(), CSCDetId::layer(), CSCRecHit2D::localPosition(), maxRatioResidual, protoIntercept, protoSegment, protoSlope_u, protoSlope_v, mathSSE::sqrt(), theChamber, GeomDet::toGlobal(), GeomDet::toLocal(), updateParameters(), findQualityFiles::v, PV3DBase< T, PVType, FrameType >::x(), PV3DBase< T, PVType, FrameType >::y(), detailsBasic3DVector::z, and PV3DBase< T, PVType, FrameType >::z().

Referenced by showerSeg().

                                            {
 
   // Only prune if have at least 5 hits 
   if ( protoSegment.size() < 5 ) return ;
 
 
   // Now Study residuals
       
   float maxResidual = 0.;
   float sumResidual = 0.;
   int nHits = 0;
   int badIndex = -1;
   int j = 0;
 
 
   ChamberHitContainer::const_iterator ih;
 
   for ( ih = protoSegment.begin(); ih != protoSegment.end(); ++ih ) {
     const CSCRecHit2D& hit = (**ih);
     const CSCLayer* layer  = theChamber->layer(hit.cscDetId().layer());
     GlobalPoint gp         = layer->toGlobal(hit.localPosition());
     LocalPoint lp          = theChamber->toLocal(gp);
 
     double u = lp.x();
     double v = lp.y();
     double z = lp.z();
 
     double du = protoIntercept.x() + protoSlope_u * z - u;
     double dv = protoIntercept.y() + protoSlope_v * z - v;
 
     float residual = sqrt(du*du + dv*dv);
 
     sumResidual += residual;
     nHits++;
     if ( residual > maxResidual ) {
       maxResidual = residual;
       badIndex = j;
     }
     j++;
   }
 
   float corrAvgResidual = (sumResidual - maxResidual)/(nHits -1);
 
   // Keep all hits 
   if ( maxResidual/corrAvgResidual < maxRatioResidual ) return;
 
 
   // Drop worse hit and recompute segment properties + fill
 
   ChamberHitContainer newProtoSegment;
 
   j = 0;
   for ( ih = protoSegment.begin(); ih != protoSegment.end(); ++ih ) {
     if ( j != badIndex ) newProtoSegment.push_back(*ih);
     j++;
   }
   
   protoSegment.clear();
 
   for ( ih = newProtoSegment.begin(); ih != newProtoSegment.end(); ++ih ) {
     protoSegment.push_back(*ih);
   }
 
   // Update segment parameters
   updateParameters();
 
 }

CSCSegment CSCSegAlgoShowering::showerSeg	(	const CSCChamber *	aChamber,
		const ChamberHitContainer &	rechits
	)

Definition at line 52 of file CSCSegAlgoShowering.cc.

References calculateError(), compareProtoSegment(), CSCRecHit2D::cscDetId(), diffTreeTool::diff, dPhi(), flipErrors(), h, i, customizeTrackingMonitorSeedNumber::idx, isHitNearSegment(), CSCChamber::layer(), CSCDetId::layer(), CSCRecHit2D::localPosition(), PV3DBase< T, PVType, FrameType >::mag(), maxDPhi, maxDTheta, gen::n, Geom::Phi< T >::phi(), PV3DBase< T, PVType, FrameType >::phi(), protoChi2, protoDirection, protoIntercept, protoSegment, protoSlope_u, protoSlope_v, pruneFromResidual(), mathSSE::sqrt(), groupFilesInBlocks::temp, theChamber, PV3DBase< T, PVType, FrameType >::theta(), GeomDet::toGlobal(), GeomDet::toLocal(), csvLumiCalc::unit, updateParameters(), x, PV3DBase< T, PVType, FrameType >::x(), detailsBasic3DVector::y, PV3DBase< T, PVType, FrameType >::y(), detailsBasic3DVector::z, and PV3DBase< T, PVType, FrameType >::z().

Referenced by CSCSegAlgoDF::buildSegments(), and CSCSegAlgoST::buildSegments().

                                                                                                           {
 
   theChamber = aChamber;
   // Initialize parameters
   std::vector<float> x, y, gz;
   std::vector<int> n;
   
   
   for (int i = 0; i < 6; ++i) {
     x.push_back(0.);
     y.push_back(0.);
     gz.push_back(0.);
     n.push_back(0);
   }
 
   // Loop over hits to find center-of-mass position in each layer
   for (ChamberHitContainer::const_iterator it = rechits.begin(); it != rechits.end(); it++ ) {
     const CSCRecHit2D& hit = (**it);
     const CSCDetId id = hit.cscDetId();
     int l_id = id.layer();
     const CSCLayer* layer  = theChamber->layer(hit.cscDetId().layer());
     GlobalPoint gp         = layer->toGlobal(hit.localPosition());
     LocalPoint  lp         = theChamber->toLocal(gp);
 
     n[l_id -1]++;
     x[l_id -1] += lp.x();
     y[l_id -1] += lp.y();
     gz[l_id -1] += gp.z();
   }
 
 
   // Determine center of mass for each layer and average center of mass for chamber
   float avgChamberX = 0.;
   float avgChamberY = 0.;
   int n_lay = 0;
 
   for (unsigned i = 0; i < 6; ++i) {
     if (n[i] < 1 ) continue;
  
     x[i] = x[i]/n[i];
     y[i] = y[i]/n[i];
     avgChamberX += x[i];
     avgChamberY += y[i];
     n_lay++;
 
   }
 
   if ( n_lay > 0) {
     avgChamberX = avgChamberX / n_lay;
     avgChamberY = avgChamberY / n_lay;
   }
 
   // Create a FakeSegment origin that points back to the IP
   // Keep all this in global coordinates until last minute to avoid screwing up +/- signs !
 
   LocalPoint   lpCOM(avgChamberX, avgChamberY, 0.);
   GlobalPoint  gpCOM = theChamber->toGlobal(lpCOM);
   GlobalVector gvCOM(gpCOM.x(), gpCOM.y(), gpCOM.z());
 
   float Gdxdz = gpCOM.x()/gpCOM.z();
   float Gdydz = gpCOM.y()/gpCOM.z();
 
   // Figure out the intersection of this vector with each layer of the chamber
   // by projecting the vector
   std::vector<LocalPoint> layerPoints;
 
   for (unsigned i = 1; i < 7; i++) {
     // Get the layer z coordinates in global frame
     const CSCLayer* layer = theChamber->layer(i);
     LocalPoint temp(0., 0., 0.);
     GlobalPoint gp = layer->toGlobal(temp);
     float layer_Z = gp.z();
 
     // Then compute interesection of vector with that plane
     float layer_X = Gdxdz * layer_Z;
     float layer_Y = Gdydz * layer_Z;
     GlobalPoint Gintersect(layer_X, layer_Y, layer_Z);
     LocalPoint  Lintersect = theChamber->toLocal(Gintersect);
 
     float layerX = Lintersect.x();
     float layerY = Lintersect.y();
     float layerZ = Lintersect.z();
     LocalPoint layerPoint(layerX, layerY, layerZ);
     layerPoints.push_back(layerPoint);
   }
 
 
   std::vector<float> r_closest;
   std::vector<int> id;
   for (unsigned i = 0; i < 6; ++i ) {
     id.push_back(-1);
     r_closest.push_back(9999.);
   }
 
   int idx = 0;
 
   // Loop over all hits and find hit closest to com for that layer.
   for (ChamberHitContainer::const_iterator it = rechits.begin(); it != rechits.end(); it++ ) {    
     const CSCRecHit2D& hit = (**it);
     int layId = hit.cscDetId().layer();
     const CSCLayer* layer  = theChamber->layer(hit.cscDetId().layer());
     GlobalPoint gp         = layer->toGlobal(hit.localPosition());
     LocalPoint  lp         = theChamber->toLocal(gp);
 
     float d_x = lp.x() - layerPoints[layId-1].x();
     float d_y = lp.y() - layerPoints[layId-1].y();
 
     LocalPoint diff(d_x, d_y, 0.);
     
     if ( fabs(diff.mag() ) < r_closest[layId-1] ) {
        r_closest[layId-1] =  fabs(diff.mag());
        id[layId-1] = idx;
     }
     idx++;
   }
 
   // Now fill vector of rechits closest to center of mass:
   protoSegment.clear();
   idx = 0;
 
   // Loop over all hits and find hit closest to com for that layer.
   for (ChamberHitContainer::const_iterator it = rechits.begin(); it != rechits.end(); it++ ) {    
     const CSCRecHit2D& hit = (**it);
     int layId = hit.cscDetId().layer();
 
     if ( idx == id[layId-1] )protoSegment.push_back(*it);
 
     idx++;    
   }
 
   // Reorder hits in protosegment
   if ( gz[0] > 0. ) {
     if ( gz[0] > gz[5] ) { 
       reverse( protoSegment.begin(), protoSegment.end() );
     }    
   }
   else if ( gz[0] < 0. ) {
     if ( gz[0] < gz[5] ) {
       reverse( protoSegment.begin(), protoSegment.end() );
     }    
   }
 
 
   // Compute the segment properties
   updateParameters();
 
   // Clean up protosegment if there is one very bad hit on segment
   if (protoSegment.size() > 4) pruneFromResidual();
 
   // Look for better hits near segment  
   for (ChamberHitContainer::const_iterator it = rechits.begin(); it != rechits.end(); it++ ) {
 
     const CSCRecHit2D* h = *it;
     int layer = h->cscDetId().layer();
 
     if ( isHitNearSegment( h ) ) compareProtoSegment(h, layer);
   }
 
   // Prune worse hit if necessary
   if ( protoSegment.size() > 5 ) pruneFromResidual();
 
   // Update the parameters
   updateParameters();
 
   // Local direction
   double dz   = 1./sqrt(1. + protoSlope_u*protoSlope_u + protoSlope_v*protoSlope_v);
   double dx   = dz*protoSlope_u;
   double dy   = dz*protoSlope_v;
   LocalVector localDir(dx,dy,dz);
         
   // localDir may need sign flip to ensure it points outward from IP  
   double globalZpos    = ( theChamber->toGlobal( protoIntercept ) ).z();
   double globalZdir    = ( theChamber->toGlobal( localDir ) ).z();
   double directionSign = globalZpos * globalZdir;
   LocalVector protoDirection = (directionSign * localDir).unit();
 
   // Check to make sure the fitting didn't fuck things up
   GlobalVector protoGlobalDir = theChamber->toGlobal( protoDirection );  
   double protoTheta = protoGlobalDir.theta();
   double protoPhi = protoGlobalDir.phi();
   double simTheta = gvCOM.theta();
   double simPhi = gvCOM.phi();
   
   float dTheta = fabs(protoTheta - simTheta);
   float dPhi   = fabs(protoPhi - simPhi);
   //  float dR = sqrt(dEta*dEta + dPhi*dPhi);
   
   // Error matrix
   AlgebraicSymMatrix protoErrors = calculateError();     
   // but reorder components to match what's required by TrackingRecHit interface
   // i.e. slopes first, then positions
   flipErrors( protoErrors );
   
   //Flag the segment with chi12 of -1 of the segment isn't pointing toward origin      
   if (dTheta > maxDTheta || dPhi > maxDPhi) {
   CSCSegment temp(protoSegment, protoIntercept, protoDirection, protoErrors, -1); 
   return temp;
   }
   else {
   CSCSegment temp(protoSegment, protoIntercept, protoDirection, protoErrors, protoChi2);
   return temp;
   }
 
 } 

void CSCSegAlgoShowering::updateParameters ( void )

private

Definition at line 323 of file CSCSegAlgoShowering.cc.

References CSCRecHit2D::cscDetId(), CSCChamber::layer(), CSCDetId::layer(), CSCRecHit2D::localPosition(), CSCRecHit2D::localPositionError(), LogDebug, AlCaHLTBitMon_ParallelJobs::p, protoChi2, protoIntercept, protoSegment, protoSlope_u, protoSlope_v, theChamber, GeomDet::toGlobal(), GeomDet::toLocal(), findQualityFiles::v, PV3DBase< T, PVType, FrameType >::x(), LocalError::xx(), LocalError::xy(), PV3DBase< T, PVType, FrameType >::y(), LocalError::yy(), detailsBasic3DVector::z, and PV3DBase< T, PVType, FrameType >::z().

Referenced by compareProtoSegment(), pruneFromResidual(), and showerSeg().

                                            {
 
   // Compute slope from Least Square Fit    
   CLHEP::HepMatrix M(4,4,0);
   CLHEP::HepVector B(4,0);
 
   ChamberHitContainer::const_iterator ih;
   
   for (ih = protoSegment.begin(); ih != protoSegment.end(); ++ih) {
     
     const CSCRecHit2D& hit = (**ih);
     const CSCLayer* layer  = theChamber->layer(hit.cscDetId().layer());
     GlobalPoint gp         = layer->toGlobal(hit.localPosition());
     LocalPoint  lp         = theChamber->toLocal(gp); 
     
     double u = lp.x();
     double v = lp.y();
     double z = lp.z();
     
     // ptc: Covariance matrix of local errors 
     CLHEP::HepMatrix IC(2,2);
     IC(1,1) = hit.localPositionError().xx();
     IC(1,2) = hit.localPositionError().xy();
     IC(2,2) = hit.localPositionError().yy();
     IC(2,1) = IC(1,2); // since Cov is symmetric
     
     // ptc: Invert covariance matrix (and trap if it fails!)
     int ierr = 0;
     IC.invert(ierr); // inverts in place
     if (ierr != 0) {
       LogDebug("CSC") << "CSCSegment::fitSlopes: failed to invert covariance matrix=\n" << IC << "\n";      
     }
     
     M(1,1) += IC(1,1);
     M(1,2) += IC(1,2);
     M(1,3) += IC(1,1) * z;
     M(1,4) += IC(1,2) * z;
     B(1)   += u * IC(1,1) + v * IC(1,2);
     
     M(2,1) += IC(2,1);
     M(2,2) += IC(2,2);
     M(2,3) += IC(2,1) * z;
     M(2,4) += IC(2,2) * z;
     B(2)   += u * IC(2,1) + v * IC(2,2);
     
     M(3,1) += IC(1,1) * z;
     M(3,2) += IC(1,2) * z;
     M(3,3) += IC(1,1) * z * z;
     M(3,4) += IC(1,2) * z * z;
     B(3)   += ( u * IC(1,1) + v * IC(1,2) ) * z;
     
     M(4,1) += IC(2,1) * z;
     M(4,2) += IC(2,2) * z;
     M(4,3) += IC(2,1) * z * z;
     M(4,4) += IC(2,2) * z * z;
     B(4)   += ( u * IC(2,1) + v * IC(2,2) ) * z;
   }
   
   CLHEP::HepVector p = solve(M, B);
   
   // Update member variables 
   // Note that origin has local z = 0
 
   protoIntercept = LocalPoint(p(1), p(2), 0.);
   protoSlope_u = p(3);
   protoSlope_v = p(4);
 
   // Determine Chi^2 for the proto wire segment
   
   double chsq = 0.;
   
   for (ih = protoSegment.begin(); ih != protoSegment.end(); ++ih) {
     
     const CSCRecHit2D& hit = (**ih);
     const CSCLayer* layer  = theChamber->layer(hit.cscDetId().layer());
     GlobalPoint gp         = layer->toGlobal(hit.localPosition());
     LocalPoint lp          = theChamber->toLocal(gp);
     
     double u = lp.x();
     double v = lp.y();
     double z = lp.z();
     
     double du = protoIntercept.x() + protoSlope_u * z - u;
     double dv = protoIntercept.y() + protoSlope_v * z - v;
     
     CLHEP::HepMatrix IC(2,2);
     IC(1,1) = hit.localPositionError().xx();
     IC(1,2) = hit.localPositionError().xy();
     IC(2,2) = hit.localPositionError().yy();
     IC(2,1) = IC(1,2);
     
     // Invert covariance matrix
     int ierr = 0;
     IC.invert(ierr);
     if (ierr != 0) {
       LogDebug("CSC") << "CSCSegment::fillChiSquared: failed to invert covariance matrix=\n" << IC << "\n";      
     }
     chsq += du*du*IC(1,1) + 2.*du*dv*IC(1,2) + dv*dv*IC(2,2);
   }
   protoChi2 = chsq;
 }

AlgebraicSymMatrix CSCSegAlgoShowering::weightMatrix ( void ) const

private

Definition at line 467 of file CSCSegAlgoShowering.cc.

References CSCRecHit2D::localPositionError(), makeMuonMisalignmentScenario::matrix, protoSegment, LocalError::xx(), LocalError::xy(), and LocalError::yy().

Referenced by calculateError().

                                                            {
 
   std::vector<const CSCRecHit2D*>::const_iterator it;
   int nhits = protoSegment.size();
   AlgebraicSymMatrix matrix(2*nhits, 0);
   int row = 0;
 
   for (it = protoSegment.begin(); it != protoSegment.end(); ++it) {
 
     const CSCRecHit2D& hit = (**it);
     ++row;
     matrix(row, row)   = hit.localPositionError().xx();
     matrix(row, row+1) = hit.localPositionError().xy();
     ++row;
     matrix(row, row-1) = hit.localPositionError().xy();
     matrix(row, row)   = hit.localPositionError().yy();
   }
   int ierr;
   matrix.invert(ierr);
   return matrix;
 }