// azimuthal angle of the centre of the TPC sector in which the point
// xyz lies
//
+ const double kSafe = 1e-5;
Double_t radPos2 = xyz[0]*xyz[0]+xyz[1]*xyz[1];
Double_t radMax = 45.; // approximately ITS outer radius
- if (radPos2 < radMax*radMax) { // inside the ITS
-
+ if (radPos2 < radMax*radMax) { // inside the ITS
fAlpha = TMath::ATan2(pxpypz[1],pxpypz[0]);
} else { // outside the ITS
Float_t phiPos = TMath::Pi()+TMath::ATan2(-xyz[1], -xyz[0]);
fAlpha =
TMath::DegToRad()*(20*((((Int_t)(phiPos*TMath::RadToDeg()))/20))+10);
}
-
+ //
+ Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
+ // protection: avoid alpha being too close to 0 or +-pi/2
+ if (TMath::Abs(sn)<kSafe) {
+ fAlpha = kSafe;
+ cs=TMath::Cos(fAlpha);
+ sn=TMath::Sin(fAlpha);
+ }
+ else if (cs<kSafe) {
+ fAlpha -= TMath::Sign(kSafe, fAlpha);
+ cs=TMath::Cos(fAlpha);
+ sn=TMath::Sin(fAlpha);
+ }
// Get the vertex of origin and the momentum
TVector3 ver(xyz[0],xyz[1],xyz[2]);
TVector3 mom(pxpypz[0],pxpypz[1],pxpypz[2]);
+ //
+ // avoid momenta along axis
+ if (TMath::Abs(mom[0])<kSafe) mom[0] = TMath::Sign(kSafe*TMath::Abs(mom[1]), mom[0]);
+ if (TMath::Abs(mom[1])<kSafe) mom[1] = TMath::Sign(kSafe*TMath::Abs(mom[0]), mom[1]);
// Rotate to the local coordinate system
ver.RotateZ(-fAlpha);
// Covariance matrix (formulas to be simplified)
Double_t pt=1./TMath::Abs(fP[4]);
- Double_t cs=TMath::Cos(fAlpha), sn=TMath::Sin(fAlpha);
Double_t r=TMath::Sqrt((1.-fP[2])*(1.+fP[2]));
Double_t m00=-sn;// m10=cs;
Double_t f1=fP[2], f2=f1 + x2r;
if (TMath::Abs(f1) >= kAlmost1) return kFALSE;
if (TMath::Abs(f2) >= kAlmost1) return kFALSE;
+ if (TMath::Abs(fP[4])< kAlmost0) return kFALSE;
Double_t &fP0=fP[0], &fP1=fP[1], &fP2=fP[2], &fP3=fP[3], &fP4=fP[4];
Double_t
&fC40=fC[10], &fC41=fC[11], &fC42=fC[12], &fC43=fC[13], &fC44=fC[14];
Double_t r1=TMath::Sqrt((1.-f1)*(1.+f1)), r2=TMath::Sqrt((1.-f2)*(1.+f2));
+ if (TMath::Abs(r1)<kAlmost0) return kFALSE;
+ if (TMath::Abs(r2)<kAlmost0) return kFALSE;
fX=xk;
double dy2dx = (f1+f2)/(r1+r2);