Go to the documentation of this file.00001 #include "ThirdHitZPrediction.h"
00002 template<class T> T sqr(T t) { return t * t; }
00003
00004 ThirdHitZPrediction::ThirdHitZPrediction(
00005 const GlobalPoint& p1, float erroRPhi1, float errorZ1,
00006 const GlobalPoint& p2, float erroRPhi2, float errorZ2,
00007 double curvature, double nSigma)
00008 :
00009 thePoint1(p1), thePoint2(p2),
00010 theErrorXY1(erroRPhi1), theErrorZ1(errorZ1),
00011 theErrorXY2(erroRPhi2), theErrorZ2(errorZ2),
00012 theCurvature(curvature), theNSigma(nSigma)
00013 {}
00014
00015 ThirdHitZPrediction::Range ThirdHitZPrediction::operator()(
00016 const GlobalPoint& thePoint3, float erroRPhi3) const
00017 {
00018 double dR12 = (thePoint2-thePoint1).perp();
00019 if (dR12 < 1.e-5) dR12 = 1.e-5;
00020 double dR23 = (thePoint3-thePoint2).perp();
00021 double dZ12 = thePoint2.z()-thePoint1.z();
00022
00023 double slope = dR23/dR12;
00024 if ( (theCurvature > 1.e-4)
00025 && (fabs(dR23/2.*theCurvature) < 1.)
00026 && (fabs(dR12/2.*theCurvature) <1.)
00027 ) slope = asin(dR23/2.*theCurvature)/asin(dR12/2.*theCurvature);
00028
00029 double z3 = thePoint2.z() + dZ12*slope;
00030
00031 double sqr_errorXY12 = sqr(theErrorXY1)+sqr(theErrorXY2);
00032 double sqr_errorXY23 = sqr(theErrorXY2)+sqr(erroRPhi3);
00033 double error = sqrt( sqr( (1+dR23/dR12)*theErrorZ2 )
00034 + sqr( dR23/dR12 * theErrorZ1 )
00035 + sqr(dZ12/dR12 )*sqr_errorXY23
00036 + sqr(dZ12*dR23/dR12/dR12)*sqr_errorXY12
00037 );
00038 error *= theNSigma;
00039 return Range(z3-error,z3+error);
00040 }
00041
1.7.3