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econte |
1.1 |
#include "TrackingTools/PatternTools/interface/TwoTrackMinimumDistanceHelixLine.h"
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#include "TrackingTools/TrajectoryParametrization/interface/GlobalTrajectoryParameters.h"
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#include "MagneticField/Engine/interface/MagneticField.h"
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#include "FWCore/MessageLogger/interface/MessageLogger.h"
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#include <iostream>
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#include <iomanip>
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using namespace std;
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bool TwoTrackMinimumDistanceHelixLine::updateCoeffs()
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{
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if (firstGTP->charge() == 0. && secondGTP->charge() != 0.) {
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theL= firstGTP;
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theH= secondGTP;
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} else if (firstGTP->charge() != 0. && secondGTP->charge() == 0.) {
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theH= firstGTP;
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theL= secondGTP;
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} else {
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edm::LogWarning ("TwoTrackMinimumDistanceHelixLine")
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<< "Error in track charge: "
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<< "One of the tracks has to be charged, and the other not." << endl
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<< "Track Charges: "<<firstGTP->charge() << " and " <<secondGTP->charge();
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return true;
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}
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Hn = theH->momentum().mag();
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Ln = theL->momentum().mag();
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if ( Hn == 0. || Ln == 0. )
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{
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edm::LogWarning ("TwoTrackMinimumDistanceHelixLine")
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<< "Momentum of input trajectory is zero.";
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return true;
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};
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GlobalPoint lOrig = theL->position();
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GlobalPoint hOrig = theH->position();
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posDiff = GlobalVector((lOrig - hOrig).basicVector());
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X = posDiff.x();
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Y = posDiff.y();
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Z = posDiff.z();
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theLp = theL->momentum();
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px = theLp.x(); px2 = px*px;
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py = theLp.y(); py2 = py*py;
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pz = theLp.z(); pz2 = pz*pz;
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const double Bc2kH = theH->magneticField().inTesla(hOrig).z() * 2.99792458e-3;
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// MagneticField::inInverseGeV ( hOrig ).z();
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if ( Bc2kH == 0. )
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{
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edm::LogWarning ("TwoTrackMinimumDistanceHelixLine")
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<< "Magnetic field at point " << hOrig << " is zero.";
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return true;
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};
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theh= - Hn / (theH->charge() * Bc2kH ) *
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sqrt( 1 - ( ( (theH->momentum().z()*theH->momentum().z()) / (Hn*Hn) )));
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thetanlambdaH = - theH->momentum().z() / ( theH->charge() * Bc2kH * theh);
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thePhiH0 = theH->momentum().phi();
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thesinPhiH0= sin(thePhiH0);
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thecosPhiH0= cos(thePhiH0);
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aa = (X + theh*thesinPhiH0)*(py2 + pz2) - px*(py*Y + pz*Z);
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bb = (Y - theh*thecosPhiH0)*(px2 + pz2) - py*(px*X + pz*Z);
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cc = pz*theh*thetanlambdaH;
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dd = theh* px *py;
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ee = theh*(px2 - py2);
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ff = (px2 + py2)*theh*thetanlambdaH*thetanlambdaH;
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baseFct = thetanlambdaH * (Z*(px2+py2) - pz*(px*X + py*Y));
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baseDer = - ff;
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return false;
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}
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bool TwoTrackMinimumDistanceHelixLine::oneIteration(
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double & thePhiH, double & fct, double & derivative ) const
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{
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double thesinPhiH = sin(thePhiH);
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double thecosPhiH = cos(thePhiH);
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// Fonction of which the root is to be found:
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fct = baseFct;
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fct -= ff*(thePhiH - thePhiH0);
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fct += thecosPhiH * aa;
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fct += thesinPhiH * bb;
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fct += cc*(thePhiH - thePhiH0)*(px * thecosPhiH + py * thesinPhiH);
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fct += cc * (px * (thesinPhiH - thesinPhiH0) - py * (thecosPhiH - thecosPhiH0));
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fct += dd * (thesinPhiH* (thesinPhiH - thesinPhiH0) -
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thecosPhiH*(thecosPhiH - thecosPhiH0));
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fct += ee * thecosPhiH * thesinPhiH;
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// Its derivative:
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derivative = baseDer;
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derivative += - thesinPhiH * aa;
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derivative += thecosPhiH * bb;
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derivative += cc*(thePhiH - thePhiH0)*(py * thecosPhiH - px * thesinPhiH);
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derivative += 2* cc*(px * thecosPhiH + py * thesinPhiH);
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derivative += dd *(4 * thecosPhiH * thesinPhiH - thecosPhiH * thesinPhiH0 -
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thesinPhiH * thecosPhiH0);
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derivative += ee * (thecosPhiH*thecosPhiH-thesinPhiH*thesinPhiH);
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return false;
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}
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bool TwoTrackMinimumDistanceHelixLine::calculate(
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const GlobalTrajectoryParameters & theFirstGTP,
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const GlobalTrajectoryParameters & theSecondGTP, const float qual )
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{
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pointsUpdated = false;
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firstGTP = (GlobalTrajectoryParameters *) &theFirstGTP;
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secondGTP = (GlobalTrajectoryParameters *) &theSecondGTP;
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if ( updateCoeffs () )
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{
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return true;
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};
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double fctVal, derVal, dPhiH;
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thePhiH = thePhiH0;
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double x1=thePhiH0-M_PI, x2=thePhiH0+M_PI;
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for (int j=1; j<=themaxiter; ++j) {
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oneIteration(thePhiH, fctVal, derVal);
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dPhiH=fctVal/derVal;
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thePhiH -= dPhiH;
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if ((x1-thePhiH)*(thePhiH-x2) < 0.0) {
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LogDebug ("TwoTrackMinimumDistanceHelixLine")
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<< "Jumped out of brackets in root finding. Will be moved closer.";
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thePhiH += (dPhiH*0.8);
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}
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if (fabs(dPhiH) < qual) {return false;}
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}
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LogDebug ("TwoTrackMinimumDistanceHelixLine")
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<<"Number of steps exceeded. Has not converged.";
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return true;
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}
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double TwoTrackMinimumDistanceHelixLine::firstAngle() const
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{
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if (firstGTP==theL) return theL->momentum().phi();
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else return thePhiH;
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}
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double TwoTrackMinimumDistanceHelixLine::secondAngle() const
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{
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if (secondGTP==theL) return theL->momentum().phi();
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else return thePhiH;
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}
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pair <GlobalPoint, GlobalPoint> TwoTrackMinimumDistanceHelixLine::points()
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const
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{
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if (!pointsUpdated)finalPoints();
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if (firstGTP==theL)
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return pair<GlobalPoint, GlobalPoint> (linePoint, helixPoint);
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else return pair<GlobalPoint, GlobalPoint> (helixPoint, linePoint);
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}
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pair <double, double> TwoTrackMinimumDistanceHelixLine::pathLength() const
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{
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if (!pointsUpdated)finalPoints();
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if (firstGTP==theL)
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return pair<double, double> (linePath, helixPath);
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else return pair<double, double> (helixPath, linePath);
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}
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void TwoTrackMinimumDistanceHelixLine::finalPoints() const
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{
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helixPoint = GlobalPoint (
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theH->position().x() + theh * ( sin ( thePhiH) - thesinPhiH0 ),
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theH->position().y() + theh * ( - cos ( thePhiH) + thecosPhiH0 ),
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theH->position().z() + theh * ( thetanlambdaH * ( thePhiH- thePhiH0 ))
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);
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helixPath = ( thePhiH- thePhiH0 ) * (theh*sqrt(1+thetanlambdaH*thetanlambdaH)) ;
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GlobalVector diff((theL->position() -helixPoint).basicVector());
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tL = ( - diff.dot(theLp)) / (Ln*Ln);
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linePoint = GlobalPoint (
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theL->position().x() + tL * px,
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theL->position().y() + tL * py,
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theL->position().z() + tL * pz );
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linePath = tL * theLp.mag();
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pointsUpdated = true;
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}
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