THelix
class description - source file - inheritance tree
protected:
Double_t FindClosestPhase(Double_t phi0, Double_t cosine)
void SetRotMatrix()
public:
THelix THelix()
THelix THelix(Double_t x, Double_t y, Double_t z, Double_t vx, Double_t vy, Double_t vz, Double_t w)
THelix THelix(Double_t* xyz, Double_t* v, Double_t w, Double_t* range = 0, EHelixRangeType rtype = kHelixZ, Double_t* axis = 0)
THelix THelix(THelix& helix)
virtual void ~THelix()
TClass* Class()
virtual void Copy(TObject& helix)
virtual void Draw(Option_t* option)
virtual Option_t* GetOption()
virtual Bool_t Is3D()
virtual TClass* IsA()
virtual void Paint(Option_t* option)
virtual void Print(Option_t* option)
virtual void SavePrimitive(ofstream& out, Option_t* option)
virtual void SetAxis(Double_t* axis)
virtual void SetAxis(Double_t x, Double_t y, Double_t z)
void SetHelix(Double_t* xyz, Double_t* v, Double_t w, Double_t* range = 0, EHelixRangeType type = kUnchanged, Double_t* axis = 0)
virtual void SetOption(Option_t* option)
virtual void SetRange(Double_t* range, EHelixRangeType rtype = kHelixZ)
virtual void SetRange(Double_t r1, Double_t r2, EHelixRangeType rtype = kHelixZ)
virtual void ShowMembers(TMemberInspector& insp, char* parent)
virtual void Sizeof3D()
virtual void Streamer(TBuffer& b)
protected:
Double_t fX0 Initial X position
Double_t fY0 Initial Y position
Double_t fZ0 Initial Z position
Double_t fVt Transverse velocity (constant of motion)
Double_t fPhi0 Initial phase, so vx0 = fVt*cos(fPhi0)
Double_t fVz Z velocity (constant of motion)
Double_t fW Angular frequency
Double_t fAxis[3] Direction unit vector of the helix axis
TRotMatrix* fRotMat Rotation matrix: axis // z --> axis // fAxis
Double_t fRange[2] Range of helix parameter t
static Int_t fgMinNSeg minimal number of segments in polyline
Helix is, hmmm, well, a helix. It has 3 different constructors.
Comments/suggestions/etc on this class should be sent to the author:
pyeh@cdfsga.fnal.gov (Ping Yeh)
If a particle with charge q passes through a point (x,y,z)
with momentum (px,py,pz) with magnetic field B along an axis (nx,ny,nz),
this helix can be constrcuted like
THelix p(x0,y0,z0, px,py,pz, q*B, nx,ny,nz);
(nx,ny,nz) defaults to (0,0,1).
A helix in its own frame can be defined with initial position
(x0,y0,z0) and "velocity" (vx0,vy0,vz0), both 3-vectors, and
an angular frequency w. The parametric equation of the helix is
x = x0 - vt / w * sin(-w * t + phi0)
y = y0 + vt / w * cos(-w * t + phi0)
z = z0 + vz * t
The 'normal constructor' has 6 parameters,
Example:
THelix pl1(xyz0, v0, w, range, rtype, axis);
where:
xyz0 : array of initial position
v0 : array of initial velocity
w : angular frequency
range : helix range
rtype : kHelixZ specifies allowed drawing range in helix Z direction, i.e., along B field.
kLabZ specifies drawing range in lab frame.
kHelixX, kHelixY, kLabX, kLabY, kUnchanged ... etc can also be specified
axis : helix axis
A Third constructor uses several default values:
Example:
c1 = new TCanvas("c1");
TView *view = new TView(1);
view->SetRange(-1,-1,-1,1,1,1);
THelix *helix = new THelix(0.0, 0.0, 0.0, 1.0, 0.0, 0.3, 10.0);
helix->Draw();
will initializes a helix with its axis in Z direction (rtype=kHelixZ).
range[0] = 0 and range[1] = 1
______________________________________________________________________________
void SetHelix(Double_t *p, Double_t *v, Double_t w,
Double_t *range, EHelixRangeType rType,
Double_t *axis )
Set all helix parameters.
THelix()
Helix default constructor.
THelix(Double_t x, Double_t y, Double_t z,
Double_t vx, Double_t vy, Double_t vz,
Double_t w)
: TPolyLine3D()
Helix normal constructor.
THelix(Double_t * p, Double_t * v, Double_t w,
Double_t * range, EHelixRangeType rType, Double_t * axis)
: TPolyLine3D()
Helix normal constructor.
THelix(const THelix &h) : TPolyLine3D()
Helix copy constructor.
~THelix()
Helix destructor.
THelix(const THelix &helix)
void Copy(TObject &obj)
Copy this helix to obj.
void Draw(Option_t *option)
Draw this helix with its current attributes.
void Print(Option_t *option)
Dump this helix with its attributes.
void SavePrimitive(ofstream &out, Option_t *)
Save primitive as a C++ statement(s) on output stream out.
void SetAxis(Double_t * axis)
Set a new axis for the helix. This will make a new rotation matrix.
void SetAxis(Double_t x, Double_t y, Double_t z)
void SetRange(Double_t * range, EHelixRangeType rType)
set a new range for the helix. This will remake the polyline.
void SetRange(Double_t r1, Double_t r2, EHelixRangeType rType)
void Sizeof3D() const
Return total X3D size of this shape with its attributes.
void SetRotMatrix()
set the rotational matrix according to the helix axis
Double_t FindClosestPhase(Double_t phi0, Double_t cosine)
Finds the closest phase to phi0 that gives cos(phase) = cosine
Inline Functions
Option_t* GetOption()
Bool_t Is3D()
void Paint(Option_t* option)
void SetOption(Option_t* option)
TClass* Class()
TClass* IsA()
void ShowMembers(TMemberInspector& insp, char* parent)
void Streamer(TBuffer& b)
Author: Ping Yeh 19/12/97
Last update: 2.20/05 17/04/99 07.50.09 by Rene Brun
Copyright (c) 1995-1999, The ROOT System, All rights reserved. *
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