class AliHMPIDReconHTA: public TNamed

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hidden algorithm
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Init some variables
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Delete variables
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 Pattern recognition method without any infos from tracking:HTA (Hidden Track Algorithm)...
 The method finds in the chmuber the cluster with the highest charge
 compatibile with a MIP, then the strategy is applied
 Arguments:  pTrk     - pointer to ESD track
             pCluLs   - list of clusters for a given chamber
             pNmean   - pointer to ref. index
             pQthre   - pointer to qthre
   Returns:           - 0=ok,1=not fitted

 Pattern recognition method without any infos from tracking...
 First a preclustering filter to avoid part of the noise
 Then only ellipsed-rings are fitted (no possibility,
 for the moment, to reconstruct very inclined tracks)
 Finally a fitting with (th,ph) free, starting by very close values
 previously evaluated.
 Arguments:   none
   Returns:   none

 Pre-filter of bkg clusters
 Arguments:    pSluLst  -  List of the clusters for a given chamber
   Returns:    status   -  TRUE if filtering leaves enough photons, FALSE if not

 Finds the estimates for phi and theta of the track and the ThetaCerenkov
 by using a database of the shapes of the rings
 Arguments:   none
   Returns:   thTrkRec  - estimate of theta track
              phiTrkRec - estimate of phi   track
              thetaCRec - estimate of ThetaCerenkov
              status    - TRUE if a good solution is found, FALSE if not

 Find a Spline curve to define dist. vs. phi angle
 in order to estimate the phi of the track
 Arguments:   np     - # points corresponding to # photon candidates
             dist    - distance of each photon from MIP
             phiphot - phi of the photon in the DRS
   Returns:  xA      - min. distance from MIP
             xB      - dist. from mip perpedicular to the major axis
             phiStart- estimate of the track phi

 It uses parabola from 3 points to evaluate the x-coord of the parab
 Arguments:    xi,yi - points
   Returns:    x-coord of the vertex

 Fit performed by minimizing RMS/sqrt(n) of the
 photons reconstructed. First phi is fixed and theta
 is fouond, then (th,ph) of the track
 as free parameters
 Arguments:    PhiRec phi of the track
   Returns:    none

 Minimization function to find best track and thetaC parameters
 Arguments:    f = function value to minimize
             par = list of parameter to find
           iflag = flag status. See Minuit instructions
   Returns:    none

 Note: it is necessary to call an instance of AlihMPIDParam. Not possible to use fParam
 because of the static instantiation of the function in Minuit

 Construction a database of ring shapes on fly
   Arguments: none
   Returns  : none
  N.B. fgDB is the distance with x-min from MIP
                                 y-dist from the ring of the MIP perpendicular to major axis
        The content is the packed info of track theta and thetaC in degrees
                        thetaC+1000*thTrk

  TFile *pout = new TFile("./database.root","recreate");

If fills eventually channel without entries
inthe histo "database" jyst interpolating the neighboring cells
 Arguments: histogram pointer of the database
   Returns: none

2nd deg. equation
solution
 Arguments: coef 2 1 0: ax^2+bx+c=0
   Returns: n. of solutions
            x1= 1st sol
            x2= 2nd sol

 Reconstruction of phiTRK angle with two methods (in switching)

 - least square method (for closed rings)
 - by minimum distance mip-photon (for open rings)