cfTotCov.cxx

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/*
  Copyright (C) 2002-2025 CERN for the benefit of the ATLAS collaboration
*/
 
// Calculates COVF(21) - symmetric 6x6 covariance matrix
// for combined (X,Y,Z,Px,Py,Pz) vector after vertex fit
//
//-----------------------------------------------------
#include "TrkVKalVrtCore/cfTotCov.h"
#include "TrkVKalVrtCore/CommonPars.h"
#include "TrkVKalVrtCore/VtCFitE.h"
#include "TrkVKalVrtCore/Utilities.h"
#include "TrkVKalVrtCore/TrkVKalVrtCoreBase.h"
#include "TrkVKalVrtCore/VKalVrtBMag.h"
#include <cmath>
 
namespace Trk {
//
//  Function calculates complete error matrix ADER and derivatives
//   of fitted track parameters with respect to initial ones.
//    It calculates also combined momentum and (VxVyVzPxPyPz) covarinace
//  Complete error matrix is recalculated here via getFullVrtCov,
//            so CPU CONSUMING!!!
//--------------------------------------------------------------
 
int afterFit(VKVertex *vk, double *ader, double * dcv, double * ptot, double * VrtMomCov, const VKalVrtControlBase* CONTROL )
{
    int i,j;
    double px,py,pz,pt,invR,cth;
    double verr[6][6]={{0.}};   //for (i=0; i<6*6; i++) verr[i]=0;
 
    int NTRK = vk->TrackList.size();
    int NVar = NTRK*3+3;
    for (i=1; i<=6; ++i) {
    for (j=1; j<=NVar  ; ++j) dcv[i + j*6 - 7] = 0.;
    }
    cfsetdiag( 6, VrtMomCov, 100.);
    ptot[0] = 0.;
    ptot[1] = 0.;
    ptot[2] = 0.;
 
    double vBx,vBy,vBz,constBF;
    Trk::vkalMagFld::getMagFld(vk->refIterV[0],vk->refIterV[1],vk->refIterV[2],vBx,vBy,vBz,CONTROL);
 
    for (i = 1; i <= NTRK; ++i) {
        VKTrack *trk=vk->TrackList[i-1].get();
        invR = trk->fitP[2];
    cth = 1. / tan(trk->fitP[0]);
    constBF=Trk::vkalMagFld::getEffField(vBx, vBy, vBz, trk->fitP[1], trk->fitP[0]) * Trk::vkalMagFld::getCnvCst();
    pt = std::abs( constBF / invR);
    px = pt * cos(trk->fitP[1]);
    py = pt * sin(trk->fitP[1]);
    pz = pt * cth;
    ptot[0] += px;
    ptot[1] += py;
    ptot[2] += pz;
    dcv[ (i*3 + 0)*6 + 5] = -pt * (cth * cth + 1);     /* dPz/d(theta) */
    dcv[ (i*3 + 1)*6 + 3] = -py;                       /* dPx/d(phi) */
    dcv[ (i*3 + 1)*6 + 4] =  px;                       /* dPy/d(phi) */
    dcv[ (i*3 + 2)*6 + 3] = -px / invR;            /* dPx/d(rho) */
    dcv[ (i*3 + 2)*6 + 4] = -py / invR;            /* dPy/d(rho) */
    dcv[ (i*3 + 2)*6 + 5] = -pz / invR;                /* dPz/d(rho) */
    }
    dcv[0]  = 1.;
    dcv[7]  = 1.;
    dcv[14] = 1.;
    if(!ader)return 0;
    int IERR=getFullVrtCov(vk, ader, dcv, verr);     if (IERR) return IERR;
    int ijk = 0;
    for ( i=0; i<6; ++i) {
    for (j=0; j<=i; ++j) {
        VrtMomCov[ijk++] = verr[i][j];
    }
    }
    return 0;
}
 
//   The same as afterFit(), but instead of fitted track parameters
//          it uses guessed track parameters. ( it's needed for cascade)
//  Complete error matrix is recalculated here via getFullVrtCov,
//            so CPU CONSUMING!!!
//--------------------------------------------------------------------------------------------------
int afterFitWithIniPar(VKVertex *vk, double *ader, double * dcv, double * ptot, double * VrtMomCov, const VKalVrtControlBase* CONTROL  )
{
    int i,j;
    double px,py,pz,pt,invR,cth;
    double verr[6][6]={{0.}};
 
 
    int NTRK = vk->TrackList.size();
    int NVar = NTRK*3+3;
    for (i=1; i<=6; ++i) {
    for (j=1; j<=NVar  ; ++j)  dcv[i + j*6 - 7] = 0.;
    }
    cfsetdiag( 6, VrtMomCov, 10.);
    ptot[0] = 0.;
    ptot[1] = 0.;
    ptot[2] = 0.;
 
    double vBx,vBy,vBz,constBF;
    Trk::vkalMagFld::getMagFld(vk->refIterV[0],vk->refIterV[1],vk->refIterV[2],vBx,vBy,vBz,CONTROL);
 
    for (i = 1; i <= NTRK; ++i) {
        VKTrack *trk=vk->TrackList[i-1].get();
        invR = trk->iniP[2];
    cth = 1. / tan(trk->iniP[0]);
        constBF=Trk::vkalMagFld::getEffField(vBx, vBy, vBz, trk->fitP[1], trk->fitP[0]) * Trk::vkalMagFld::getCnvCst();
    pt = std::abs( constBF/invR );
    px = pt * cos(trk->iniP[1]);
    py = pt * sin(trk->iniP[1]);
    pz = pt * cth;
    ptot[0] += px;
    ptot[1] += py;
    ptot[2] += pz;
    dcv[ (i*3 + 0)*6 + 5] = -pt * (cth * cth + 1);     /* dPz/d(theta) */
    dcv[ (i*3 + 1)*6 + 3] = -py;                       /* dPx/d(phi) */
    dcv[ (i*3 + 1)*6 + 4] =  px;                       /* dPy/d(phi) */
    dcv[ (i*3 + 2)*6 + 3] = -px / invR;            /* dPx/d(rho) */
    dcv[ (i*3 + 2)*6 + 4] = -py / invR;            /* dPy/d(rho) */
    dcv[ (i*3 + 2)*6 + 5] = -pz / invR;                /* dPz/d(rho) */
    }
    dcv[0]  = 1.;
    dcv[7]  = 1.;
    dcv[14] = 1.;
    if(!ader)return 0;
    int IERR=getFullVrtCov(vk, ader, dcv, verr);     if (IERR) return IERR;
    int ijk = 0;
    for ( i=0; i<6; ++i) {
    for (j=0; j<=i; ++j) {
        VrtMomCov[ijk++] = verr[i][j];
    }
    }
    return 0;
}
 
} /* End of namespace */