/usr/include/root/TGeoHelix.h is in libroot-geom-dev 5.34.19+dfsg-1.2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// Author: Andrei Gheata 28/04/04
/*************************************************************************
* Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *
* All rights reserved. *
* *
* For the licensing terms see $ROOTSYS/LICENSE. *
* For the list of contributors see $ROOTSYS/README/CREDITS. *
*************************************************************************/
#ifndef ROOT_TGeoHelix
#define ROOT_TGeoHelix
#ifndef ROOT_TObject
#include "TObject.h"
#endif
class TGeoHMatrix;
////////////////////////////////////////////////////////////////////////////
// //
// TGeoHelix - A helix defined by: //
// x = (1/c) * COS(phi) //
// y = (1/c) * SIN(phi) //
// z = s * alfa //
// where: //
// c = 1/Rxy - curvature in XY plane //
// phi - phi angle //
// S = 2*PI*s - vertical separation between helix loops //
// //
////////////////////////////////////////////////////////////////////////////
class TGeoHelix : public TObject
{
private :
Double_t fC; // curvature in XY plane
Double_t fS; // Z step of the helix / 2*PI
Double_t fStep; // current step
Double_t fPhi; // phi angle
Double_t fPointInit[3]; // initial point
Double_t fDirInit[3]; // normalized initial direction
Double_t fPoint[3]; // point after a step
Double_t fDir[3]; // direction after a step
Double_t fB[3]; // normalized direction for magnetic field
Int_t fQ; // right/left-handed (+/- 1) - "charge"
TGeoHMatrix *fMatrix; // transformation of local helix frame to MARS
TGeoHelix(const TGeoHelix&); // Not implemented
TGeoHelix &operator=(const TGeoHelix&); // Not implemented
public:
enum EGeoHelixTypes {
kHelixNeedUpdate = BIT(16),
kHelixStraigth = BIT(17),
kHelixCircle = BIT(18)
};
// constructors
TGeoHelix();
TGeoHelix(Double_t curvature, Double_t step, Int_t charge=1);
// destructor
virtual ~TGeoHelix();
void InitPoint(Double_t x0, Double_t y0, Double_t z0);
void InitPoint(Double_t *point);
void InitDirection(Double_t dirx, Double_t diry, Double_t dirz, Bool_t is_normalized=kTRUE);
void InitDirection(Double_t *dir, Bool_t is_normalized=kTRUE);
Double_t ComputeSafeStep(Double_t epsil=1E-6) const;
const Double_t *GetCurrentPoint() const {return fPoint;}
const Double_t *GetCurrentDirection() const {return fDir;}
Double_t GetXYcurvature() const {return fC;}
Double_t GetStep() const {return fStep;}
Double_t GetTotalCurvature() const;
Bool_t IsRightHanded() const {return (fQ>0)?kFALSE:kTRUE;} // a positive charge in B field makes a left-handed helix
void ResetStep();
Double_t StepToPlane(Double_t *point, Double_t *norm);
// Double_t *StepToPlane(Double_t a, Double_t b, Double_t c);
void SetCharge(Int_t charge);
void SetXYcurvature(Double_t curvature);
void SetField(Double_t bx, Double_t by, Double_t bz, Bool_t is_normalized=kTRUE);
void SetHelixStep(Double_t hstep);
void Step(Double_t step);
void UpdateHelix();
ClassDef(TGeoHelix, 1) // helix class
};
#endif
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