Double_t CalcAngle(Double_t phi, Double_t phi0, Double_t phiRP, Double_t v2, Double_t v1=0.)
{
Double_t CalcAngle(Double_t phi, Double_t phi0, Double_t phiRP, Double_t v2, Double_t v1=0.)
{
Double_t phi1 = phi-(phi+2*v1*TMath::Sin(phi-phiRP)+v2*TMath::Sin(2*(phi-phiRP))-phi0)/
(1.+2*v1*TMath::Cos(phi-phiRP)+ 2*v2*TMath::Cos(2*(phi-phiRP)));
if(TMath::Abs(phi/phi1-1.)<0.00001) return phi1;
Double_t phi1 = phi-(phi+2*v1*TMath::Sin(phi-phiRP)+v2*TMath::Sin(2*(phi-phiRP))-phi0)/
(1.+2*v1*TMath::Cos(phi-phiRP)+ 2*v2*TMath::Cos(2*(phi-phiRP)));
if(TMath::Abs(phi/phi1-1.)<0.00001) return phi1;