// -------------------------------------------------------------------------
// -----                    CbmTrackParam source file                 -----
// -----                  Created 05/02/16  by T. Ablyazimov          -----
// -------------------------------------------------------------------------
#include "CbmTrackParam.h"
#include "TMath.h"

void CbmTrackParam::Set(const FairTrackParam& ftp, Double_t time, Double_t timeError)
{
    SetX(ftp.GetX());
    SetY(ftp.GetY());
    SetZ(ftp.GetZ());
    SetTx(ftp.GetTx());
    SetTy(ftp.GetTy());
    SetQp(ftp.GetQp());
    fTime = time;
    fDTime = timeError;
    Double_t cov[15];
    ftp.CovMatrix(cov);
    SetCovMatrix(cov);
    Double_t p  = (TMath::Abs(ftp.GetQp()) > 1.e-4) ? 1. / TMath::Abs(ftp.GetQp()) : 1.e4;
    Double_t norma = TMath::Sqrt(ftp.GetTx() * ftp.GetTx() + ftp.GetTy() * ftp.GetTy() + 1);
    fPz = p / norma;
    fPx = ftp.GetTx() * fPz;
    fPy = ftp.GetTy() * fPz;
    Double_t DpzByDqp = -p * p / norma;
    Double_t DpzByDtx = -p * ftp.GetTx() / (norma * norma * norma);
    Double_t DpzByDty = -p * ftp.GetTy() / (norma * norma * norma);
    fDpz = TMath::Sqrt(DpzByDqp * DpzByDqp * cov[14] + DpzByDtx * DpzByDtx * cov[9] + DpzByDty * DpzByDty * cov[12] +
            2 * DpzByDqp * DpzByDtx * cov[11] + 2 * DpzByDqp * DpzByDty * cov[13] + 2 * DpzByDtx * DpzByDty * cov[10]);
    Double_t DpxByDqp = ftp.GetTx() * DpzByDqp;
    Double_t DpxByDtx = p * (ftp.GetTy() * ftp.GetTy() + 1) / (norma * norma * norma);
    Double_t DpxByDty = -p * ftp.GetTx() * ftp.GetTy() / (norma * norma * norma);
    fDpx = TMath::Sqrt(DpxByDqp * DpxByDqp * cov[14] + DpxByDtx * DpxByDtx * cov[9] + DpxByDty * DpxByDty * cov[12] +
            2 * DpxByDqp * DpxByDtx * cov[11] + 2 * DpxByDqp * DpxByDty * cov[13] + 2 * DpxByDtx * DpxByDty * cov[10]);
    Double_t DpyByDqp = ftp.GetTy() * DpzByDqp;
    Double_t DpyByDtx = -p * ftp.GetTx() * ftp.GetTy() / (norma * norma * norma);
    Double_t DpyByDty = p * (ftp.GetTx() * ftp.GetTx() + 1) / (norma * norma * norma);
    fDpy = TMath::Sqrt(DpyByDqp * DpyByDqp * cov[14] + DpyByDtx * DpyByDtx * cov[9] + DpyByDty * DpyByDty * cov[12] +
            2 * DpyByDqp * DpyByDtx * cov[11] + 2 * DpyByDqp * DpyByDty * cov[13] + 2 * DpyByDtx * DpyByDty * cov[10]);
}

ClassImp(CbmTrackParam)