// -------------------------------------------------------------------------
// -----                     FairTrackParam header file                 -----
// -----                  Created 27/01/05  by V. Friese               -----
// -------------------------------------------------------------------------


/**  FairTrackParam.h
 *@author V.Friese <v.friese@gsi.de>
 **
 ** Parameters (x, y, tx, ty, q/p) of a track
 ** resulting from the track fit. The z coordinate is not a parameter.
 ** The 5x5 covariance matrix can be set and accessed by either an array
 ** of size 15, the TMatrixFSym class or elementwise. Note that TMatrixFSym
 ** should not be used when performance is an issue.
 ** The internal representation of the covariance matrix elements is
 ** an array of double.
 **/


#ifndef FAIRSTSTRACKPARAM
#define FAIRSTSTRACKPARAM 1

#include "TObject.h"                    // for TObject

#include "Rtypes.h"                     // for Double_t, Double32_t, Int_t, etc
#include "TMatrixFSymfwd.h"             // for TMatrixFSym
#include "TVector3.h"                   // for TVector3

class FairTrackParam : public TObject
{

  public:

    /** Constructor **/
    FairTrackParam();


    /** Constructor with all variables **/
    FairTrackParam(Double_t x,  Double_t y,  Double_t z,
                   Double_t tx, Double_t ty, Double_t qp,
                   const TMatrixFSym& covMat);


    /** Copy constructor **/
    FairTrackParam(const FairTrackParam& param);


    /** Destructor **/
    virtual ~FairTrackParam();


    /** Output to screen **/
    void  Print(Option_t* option = "") const;

    /** Accessors **/
    Double_t GetX()  const { return fX; };
    Double_t GetY()  const { return fY; };
    Double_t GetZ()  const { return fZ; };
    Double_t GetTx() const { return fTx; };
    Double_t GetTy() const { return fTy; };
    Double_t GetQp() const { return fQp; };
    void Position(TVector3& pos) const { pos.SetXYZ(fX, fY, fZ); };
    void Momentum(TVector3& mom) const;
    void CovMatrix(Double_t cov[]) const;
    void CovMatrix(TMatrixFSym& covMat) const;
    Double_t GetCovariance(Int_t i, Int_t j) const;


    /** Modifiers **/
    void SetX(Double_t x)   { fX  = x;  };
    void SetY(Double_t y)   { fY  = y;  };
    void SetZ(Double_t z)   { fZ  = z;  };
    void SetTx(Double_t tx) { fTx = tx; };
    void SetTy(Double_t ty) { fTy = ty; };
    void SetQp(Double_t qp) { fQp = qp; };
    void SetPosition(const TVector3& pos);
    void SetCovMatrix(Double_t cov[]);
    void SetCovMatrix(const TMatrixFSym& covMat);
    void SetCovariance(Int_t i, Int_t j, Double_t val);


    /** Assignment operator  **/
    FairTrackParam& operator=(const FairTrackParam& par );



  private:

    /** Position of track at given z [cm] **/
    Double32_t fX, fY, fZ;

    /** Direction of track tx = dx/dz; ty = dy/dz **/
    Double32_t fTx, fTy;

    /** Charge over momentum [1/GeV] **/
    Double32_t fQp;

    /** Covariance matrix for the variables x, y, tx, ty, q/p
     ** The 15 elements of the upper triangle of the symmetric matrix
     ** are stored in an array of floats. The sequence of the array is
     ** a[0,0..4], a[1,1..4], a[2,2..4], a[3,3..4], a[4,4].
     **/

    Double32_t fCovMatrix[15];


    ClassDef(FairTrackParam,1);

};


#endif