/**************************************************************************
 * Copyright(c) 1998-1999, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/

//************************************************************************
//
//   ESD track and V0 resolution parameterization
//   
//             
//    Origin: Marian Ivanov marian.ivanov@cern.ch
//-------------------------------------------------------------------------

/*
  The track parameter resolution is determined by the intrinsic detector
  resolution and by the multiple scattering and fluctuation of the energy 
  loss in the material.

  The contribution from the intrinsic detector resolution is independent of
  the particle momenta and the mass of particle. In the limit limit of infinite
  momenta - zero curvature, the intrinsic detector resolution can be obtained.
 
  Multiple effect scaling:

  SCATERING ANGLE   - fi, theta
        sigma A   += sqrt(14.1*14.1/(beta2*p2*1e6)*TMath::Abs(xOverX0));
        sigma A    ~ 1/p
        sigma sfi  += sigma A *  sqrt((1-sfi^2) * (1+ tth^2))
        sigma tth  += sigma A * (1+tth^2)    

  MOMENTUM Pt: 
        sigma 1/pt = sigma A  * 1/pt * tth
        sigma 1/pt ~ (1/pt)^2
  
  POSITION y, z:	
        sigma y   +~ sigma A * eff length (between update measurements) ~ 1/pt 
        sigma z   +~ sigma A * eff length (between update measurements) ~ 1/pt
  Example usage:
    

*/


#include "TVectorD.h"
#include "TMath.h"
#include "TObjArray.h"
#include "AliESDresolParams.h"


ClassImp(AliESDresolParams)


 AliESDresolParams*    AliESDresolParams::fgInstance = 0; //! Instance of this class (singleton implementation)


AliESDresolParams::AliESDresolParams() :
  TObject(),  
  fResolDCAyy(0),            // resolution Y parameterization
  fResolDCAzz(0),            // resolution Z parameterization   
  fResolDCAphi(0),           // resolution phi parameterization - pt-theta
  fResolDCAth(0),            // resolution theta parameterization -pt-theta
  fResolDCA1pt(0),           // resolution 1/pt parameterization - pt-theta
  //
  fResolCyy(0),              // DCA resolution Y parameterization - r-pt
  fResolCzz(0),              // DCA resolution Z parameterization - r-pt
  fResolCphi(0),             // DCA resolution phi parameterization - r-pt
  fResolCth(0),              // DCA resolution theta parameterization - r-pt
  fResolC1pt(0)             // DCA resolution 1/pt parameterization - r-pt
{
  //
  // Default constructor
  //
}

Double_t AliESDresolParams::GetResolPrimFast(Int_t param, Float_t onept, Float_t tanth) const {
  //
  // Resolution at primary vertex
  // simple Resolution parameterization 
  // polynom of second order in 2D 
  // 
  if (!fResolDCAyy) return 0;
  TVectorD * pvec     = fResolDCAyy;
  if (param==1)  pvec = fResolDCAzz;
  if (param==2)  pvec = fResolDCAphi;
  if (param==3)  pvec = fResolDCAth;
  if (param==4)  pvec = fResolDCA1pt;
  TVectorD &vec = *pvec;
  //
  Float_t val = vec[0];
  val+= vec[1]*TMath::Abs(onept);
  val+= vec[2]*TMath::Abs(onept*onept);
  val+= vec[3]*TMath::Abs(tanth);
  val+= vec[4]*TMath::Abs(tanth*tanth);
  val+= vec[5]*TMath::Abs(onept*tanth);
  Float_t shift1pt=0;
  if (param==0 || param==1) shift1pt=0.2;
  if (param==2 || param==3) shift1pt=0.1;
  if (param==4)             shift1pt=1.;
  val*= (onept+shift1pt);  
  if (param==4) val*=(onept+shift1pt);
  return val;
}

Double_t AliESDresolParams::GetResolRFast(Int_t param, Float_t onept, Float_t radius) const {
  //
  // simple DCA resolution parameterization
  // polynom of second order in 2D 
  // 
  if (!fResolCyy) return 0;
  TVectorD * pvec     = fResolCyy;
  if (param==1)  pvec = fResolCzz;
  if (param==2)  pvec = fResolCphi;
  if (param==3)  pvec = fResolCth;
  if (param==4)  pvec = fResolC1pt;
  TVectorD &vec = *pvec;
  //
  Float_t val = vec[0];
  val+= vec[1]*TMath::Abs(onept);
  val+= vec[2]*TMath::Abs(radius);
  val+= vec[3]*TMath::Abs(onept*onept);
  val+= vec[4]*TMath::Abs(radius*radius);
  val+= vec[5]*TMath::Abs(radius*onept);
  val+= vec[6]*TMath::Abs(radius*radius*onept);
  val*=val;
  return val;
}

void AliESDresolParams::SetResolPrimFast(TObjArray* array){
  //
  // Set parameters - resolution at prim vertex
  //
  if (!array) return;  
  if (array->At(0)) 
    fResolDCAyy = new TVectorD(*((TVectorD*)array->At(0))); 
  if (array->At(1)) 
    fResolDCAzz = new TVectorD(*((TVectorD*)array->At(1))); 
  if (array->At(2)) 
    fResolDCAphi = new TVectorD(*((TVectorD*)array->At(2))); 
  if (array->At(3)) 
    fResolDCAth = new TVectorD(*((TVectorD*)array->At(3))); 
  if (array->At(4)) 
    fResolDCA1pt = new TVectorD(*((TVectorD*)array->At(4))); 
}

void AliESDresolParams::SetResolRFast(TObjArray* array){
  //
  // Set parameters - resolution at prim vertex
  //
  if (!array) return;  
  if (array->At(0)) 
    fResolCyy = new TVectorD(*((TVectorD*)array->At(0))); 
  if (array->At(1)) 
    fResolCzz = new TVectorD(*((TVectorD*)array->At(1))); 
  if (array->At(2)) 
    fResolCphi = new TVectorD(*((TVectorD*)array->At(2))); 
  if (array->At(3)) 
    fResolCth = new TVectorD(*((TVectorD*)array->At(3))); 
  if (array->At(4)) 
    fResolC1pt = new TVectorD(*((TVectorD*)array->At(4)));   
}