ROOT   Reference Guide
THelix Class Reference

THelix has two different constructors.

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 constructed like:

THelix p(x,y,z, px,py,pz, q*B, nx,ny,nz);
(nx,ny,nz) defaults to (0,0,1).
float * q
Definition: THbookFile.cxx:87
THelix has two different constructors.
Definition: THelix.h:36
Double_t y[n]
Definition: legend1.C:17
Double_t x[n]
Definition: legend1.C:17
static double B[]

A helix in its own frame can be defined with a pivotal point (x0,y0,z0), the velocity at that point (vx0,vy0,vz0), and an angular frequency w. Combining vx0 and vy0 to a transverse velocity vt0 one can parametrize the helix as:

x(t) = x0 - vt0 / w * sin(-w * t + phi0)
y(t) = y0 + vt0 / w * cos(-w * t + phi0)
z(t) = z0 + vz0 * t
double cos(double)
double sin(double)

The second constructor has 6 parameters,

Example:

THelix pl1(xyz, v, w, range, rtype, axis);

where:

• xyz : array of initial position
• v : 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

Example constructing a helix with several default values and drawing it:

{
TCanvas* helix_example_c1 = new TCanvas("helix_example_c1");
view->SetRange(-1,-1,-1,1,1,1);
THelix *helix = new THelix(0., 0., 0., 1., 0., 0.3, 10.);
helix->Draw();
}
The Canvas class.
Definition: TCanvas.h:31
virtual void Draw(Option_t *option="")
Draw this helix with its current attributes.
Definition: THelix.cxx:280
THelix()
Helix default constructor.
Definition: THelix.cxx:122
See TView3D.
Definition: TView.h:25
static TView * CreateView(Int_t system=1, const Double_t *rmin=0, const Double_t *rmax=0)
Create a concrete default 3-d view via the plug-in manager.
Definition: TView.cxx:27
virtual void SetRange(const Double_t *min, const Double_t *max)=0

This initializes a helix with its axis in Z direction (rtype=kHelixZ).

Definition at line 36 of file THelix.h.

## Public Member Functions

THelix ()
Helix default constructor. More...

THelix (const THelix &helix)
Helix copy constructor. More...

THelix (Double_t *xyz, Double_t *v, Double_t w, Double_t *range=0, EHelixRangeType rtype=kHelixZ, Double_t *axis=0)
Helix normal constructor. More...

THelix (Double_t x, Double_t y, Double_t z, Double_t vx, Double_t vy, Double_t vz, Double_t w)
Helix normal constructor. More...

virtual ~THelix ()
Helix destructor. More...

virtual void Copy (TObject &helix) const
Copy this helix to obj. More...

virtual void Draw (Option_t *option="")
Draw this helix with its current attributes. More...

Option_tGetOption () const

virtual void Print (Option_t *option="") const
Dump this helix with its attributes. More...

virtual void SavePrimitive (std::ostream &out, Option_t *option="")
Save primitive as a C++ statement(s) on output stream out. More...

virtual void SetAxis (Double_t *axis)
Set a new axis for the helix. This will make a new rotation matrix. More...

virtual void SetAxis (Double_t x, Double_t y, Double_t z)
Set axis. More...

void SetHelix (Double_t *xyz, Double_t *v, Double_t w, Double_t *range=0, EHelixRangeType type=kUnchanged, Double_t *axis=0)
Set all helix parameters. More...

virtual void SetOption (Option_t *option="")

virtual void SetRange (Double_t *range, EHelixRangeType rtype=kHelixZ)
Set a new range for the helix. This will remake the polyline. More...

virtual void SetRange (Double_t r1, Double_t r2, EHelixRangeType rtype=kHelixZ)
Set range. More...

Public Member Functions inherited from TPolyLine3D
TPolyLine3D ()
3-D polyline default constructor. More...

TPolyLine3D (const TPolyLine3D &polylin)
3-D polyline copy ctor. More...

TPolyLine3D (Int_t n, Double_t *p, Option_t *option="")
3-D polyline normal constructor. More...

TPolyLine3D (Int_t n, Double_t *x, Double_t *y, Double_t *z, Option_t *option="")
3-D polyline normal constructor. More...

TPolyLine3D (Int_t n, Float_t *p, Option_t *option="")
3-D polyline normal constructor. More...

TPolyLine3D (Int_t n, Float_t *x, Float_t *y, Float_t *z, Option_t *option="")
3-D polyline normal constructor. More...

TPolyLine3D (Int_t n, Option_t *option="")
3-D polyline normal constructor with initialization to 0. More...

virtual ~TPolyLine3D ()
3-D polyline destructor. More...

virtual void Copy (TObject &polyline) const
Copy polyline to polyline obj. More...

virtual Int_t DistancetoPrimitive (Int_t px, Int_t py)
Compute distance from point px,py to a 3-D polyline. More...

virtual void Draw (Option_t *option="")
Draw this 3-D polyline with its current attributes. More...

virtual void DrawPolyLine (Int_t n, Float_t *p, Option_t *option="")
Draw 3-D polyline with new coordinates. More...

virtual void ExecuteEvent (Int_t event, Int_t px, Int_t py)
Execute action corresponding to one event. More...

Int_t GetLastPoint () const

Int_t GetN () const

Option_tGetOption () const

Float_tGetP () const

virtual void ls (Option_t *option="") const
List this 3-D polyline. More...

virtual Int_t Merge (TCollection *list)
Merge polylines in the collection in this polyline. More...

TPolyLine3Doperator= (const TPolyLine3D &polylin)
assignment operator More...

virtual void Paint (Option_t *option="")
Paint a TPolyLine3D. More...

virtual void Print (Option_t *option="") const
Dump this 3-D polyline with its attributes on stdout. More...

virtual void SavePrimitive (std::ostream &out, Option_t *option="")
Save primitive as a C++ statement(s) on output stream. More...

virtual Int_t SetNextPoint (Double_t x, Double_t y, Double_t z)
Set point following LastPoint to x, y, z. More...

virtual void SetOption (Option_t *option="")

virtual void SetPoint (Int_t point, Double_t x, Double_t y, Double_t z)
Set point n to x, y, z. More...

virtual void SetPolyLine (Int_t n, Double_t *p, Option_t *option="")
Re-initialize polyline with n points from p. More...

virtual void SetPolyLine (Int_t n, Float_t *p, Option_t *option="")
Re-initialize polyline with n points from p. More...

virtual void SetPolyLine (Int_t n, Option_t *option="")
Re-initialize polyline with n points (0,0,0). More...

virtual Int_t Size () const

Public Member Functions inherited from TObject
TObject ()
TObject constructor. More...

TObject (const TObject &object)
TObject copy ctor. More...

virtual ~TObject ()
TObject destructor. More...

void AbstractMethod (const char *method) const
Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...

Append graphics object to current pad. More...

virtual void Browse (TBrowser *b)
Browse object. May be overridden for another default action. More...

ULong_t CheckedHash ()
Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object. More...

virtual const char * ClassName () const
Returns name of class to which the object belongs. More...

virtual void Clear (Option_t *="")

virtual TObjectClone (const char *newname="") const
Make a clone of an object using the Streamer facility. More...

virtual Int_t Compare (const TObject *obj) const
Compare abstract method. More...

virtual void Copy (TObject &object) const
Copy this to obj. More...

virtual void Delete (Option_t *option="")
Delete this object. More...

virtual Int_t DistancetoPrimitive (Int_t px, Int_t py)
Computes distance from point (px,py) to the object. More...

virtual void Draw (Option_t *option="")
Default Draw method for all objects. More...

virtual void DrawClass () const
Draw class inheritance tree of the class to which this object belongs. More...

virtual TObjectDrawClone (Option_t *option="") const
Draw a clone of this object in the current selected pad for instance with: gROOT->SetSelectedPad(gPad). More...

virtual void Dump () const
Dump contents of object on stdout. More...

virtual void Error (const char *method, const char *msgfmt,...) const
Issue error message. More...

virtual void Execute (const char *method, const char *params, Int_t *error=0)
Execute method on this object with the given parameter string, e.g. More...

virtual void Execute (TMethod *method, TObjArray *params, Int_t *error=0)
Execute method on this object with parameters stored in the TObjArray. More...

virtual void ExecuteEvent (Int_t event, Int_t px, Int_t py)
Execute action corresponding to an event at (px,py). More...

virtual void Fatal (const char *method, const char *msgfmt,...) const
Issue fatal error message. More...

virtual TObjectFindObject (const char *name) const
Must be redefined in derived classes. More...

virtual TObjectFindObject (const TObject *obj) const
Must be redefined in derived classes. More...

virtual Option_tGetDrawOption () const
Get option used by the graphics system to draw this object. More...

virtual const char * GetIconName () const
Returns mime type name of object. More...

virtual const char * GetName () const
Returns name of object. More...

virtual char * GetObjectInfo (Int_t px, Int_t py) const
Returns string containing info about the object at position (px,py). More...

virtual Option_tGetOption () const

virtual const char * GetTitle () const
Returns title of object. More...

virtual UInt_t GetUniqueID () const
Return the unique object id. More...

virtual Bool_t HandleTimer (TTimer *timer)
Execute action in response of a timer timing out. More...

virtual ULong_t Hash () const
Return hash value for this object. More...

Bool_t HasInconsistentHash () const
Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e. More...

virtual void Info (const char *method, const char *msgfmt,...) const
Issue info message. More...

virtual Bool_t InheritsFrom (const char *classname) const
Returns kTRUE if object inherits from class "classname". More...

virtual Bool_t InheritsFrom (const TClass *cl) const
Returns kTRUE if object inherits from TClass cl. More...

virtual void Inspect () const
Dump contents of this object in a graphics canvas. More...

void InvertBit (UInt_t f)

virtual Bool_t IsEqual (const TObject *obj) const
Default equal comparison (objects are equal if they have the same address in memory). More...

virtual Bool_t IsFolder () const
Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...

R__ALWAYS_INLINE Bool_t IsOnHeap () const

virtual Bool_t IsSortable () const

R__ALWAYS_INLINE Bool_t IsZombie () const

virtual void ls (Option_t *option="") const
The ls function lists the contents of a class on stdout. More...

void MayNotUse (const char *method) const
Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary). More...

virtual Bool_t Notify ()
This method must be overridden to handle object notification. More...

void Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const
Use this method to declare a method obsolete. More...

void operator delete (void *ptr)
Operator delete. More...

void operator delete[] (void *ptr)
Operator delete []. More...

voidoperator new (size_t sz)

voidoperator new (size_t sz, void *vp)

voidoperator new[] (size_t sz)

voidoperator new[] (size_t sz, void *vp)

TObjectoperator= (const TObject &rhs)
TObject assignment operator. More...

virtual void Paint (Option_t *option="")
This method must be overridden if a class wants to paint itself. More...

virtual void Pop ()
Pop on object drawn in a pad to the top of the display list. More...

virtual void Print (Option_t *option="") const
This method must be overridden when a class wants to print itself. More...

virtual Int_t Read (const char *name)
Read contents of object with specified name from the current directory. More...

virtual void RecursiveRemove (TObject *obj)
Recursively remove this object from a list. More...

void ResetBit (UInt_t f)

virtual void SaveAs (const char *filename="", Option_t *option="") const
Save this object in the file specified by filename. More...

virtual void SavePrimitive (std::ostream &out, Option_t *option="")
Save a primitive as a C++ statement(s) on output stream "out". More...

void SetBit (UInt_t f)

void SetBit (UInt_t f, Bool_t set)
Set or unset the user status bits as specified in f. More...

virtual void SetDrawOption (Option_t *option="")
Set drawing option for object. More...

virtual void SetUniqueID (UInt_t uid)
Set the unique object id. More...

virtual void SysError (const char *method, const char *msgfmt,...) const
Issue system error message. More...

R__ALWAYS_INLINE Bool_t TestBit (UInt_t f) const

Int_t TestBits (UInt_t f) const

virtual void UseCurrentStyle ()
Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked. More...

virtual void Warning (const char *method, const char *msgfmt,...) const
Issue warning message. More...

virtual Int_t Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
Write this object to the current directory. More...

virtual Int_t Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
Write this object to the current directory. More...

Public Member Functions inherited from TAttLine
TAttLine ()
AttLine default constructor. More...

TAttLine (Color_t lcolor, Style_t lstyle, Width_t lwidth)
AttLine normal constructor. More...

virtual ~TAttLine ()
AttLine destructor. More...

void Copy (TAttLine &attline) const
Copy this line attributes to a new TAttLine. More...

Int_t DistancetoLine (Int_t px, Int_t py, Double_t xp1, Double_t yp1, Double_t xp2, Double_t yp2)
Compute distance from point px,py to a line. More...

virtual Color_t GetLineColor () const
Return the line color. More...

virtual Style_t GetLineStyle () const
Return the line style. More...

virtual Width_t GetLineWidth () const
Return the line width. More...

virtual void Modify ()
Change current line attributes if necessary. More...

virtual void ResetAttLine (Option_t *option="")
Reset this line attributes to default values. More...

virtual void SaveLineAttributes (std::ostream &out, const char *name, Int_t coldef=1, Int_t stydef=1, Int_t widdef=1)
Save line attributes as C++ statement(s) on output stream out. More...

virtual void SetLineAttributes ()
Invoke the DialogCanvas Line attributes. More...

virtual void SetLineColor (Color_t lcolor)
Set the line color. More...

virtual void SetLineColorAlpha (Color_t lcolor, Float_t lalpha)
Set a transparent line color. More...

virtual void SetLineStyle (Style_t lstyle)
Set the line style. More...

virtual void SetLineWidth (Width_t lwidth)
Set the line width. More...

Public Member Functions inherited from TAtt3D
TAtt3D ()

virtual ~TAtt3D ()

virtual void Sizeof3D () const
Set total size of this 3D object (used by X3D interface). More...

## Protected Member Functions

Double_t FindClosestPhase (Double_t phi0, Double_t cosine)
Finds the closest phase to phi0 that gives cos(phase) = cosine. More...

THelixoperator= (const THelix &)
assignment operator More...

void SetRotMatrix ()
Set the rotational matrix according to the helix axis. More...

Protected Member Functions inherited from TObject
virtual void DoError (int level, const char *location, const char *fmt, va_list va) const
Interface to ErrorHandler (protected). More...

void MakeZombie ()

## Protected Attributes

Double_t fAxis [3]

Double_t fPhi0

Double_t fRange [2]

TRotMatrixfRotMat

Double_t fVt

Double_t fVz

Double_t fW

Double_t fX0

Double_t fY0

Double_t fZ0

Protected Attributes inherited from TPolyLine3D
Int_t fLastPoint
The index of the last filled point. More...

Int_t fN
Number of points. More...

TString fOption
options More...

Float_tfP
[3*fN] Array of 3-D coordinates (x,y,z) More...

Protected Attributes inherited from TAttLine
Color_t fLineColor
Line color. More...

Style_t fLineStyle
Line style. More...

Width_t fLineWidth
Line width. More...

## Static Protected Attributes

static Int_t fgMinNSeg =5

Public Types inherited from TObject
enum  {
kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 ,
}

enum  { kSingleKey = BIT(0) , kOverwrite = BIT(1) , kWriteDelete = BIT(2) }

enum  EDeprecatedStatusBits { kObjInCanvas = BIT(3) }

enum  EStatusBits {
kCanDelete = BIT(0) , kMustCleanup = BIT(3) , kIsReferenced = BIT(4) , kHasUUID = BIT(5) ,
kCannotPick = BIT(6) , kNoContextMenu = BIT(8) , kInvalidObject = BIT(13)
}

Static Public Member Functions inherited from TPolyLine3D
static void DrawOutlineCube (TList *outline, Double_t *rmin, Double_t *rmax)
Draw cube outline with 3d polylines. More...

Static Public Member Functions inherited from TObject
static Long_t GetDtorOnly ()
Return destructor only flag. More...

static Bool_t GetObjectStat ()
Get status of object stat flag. More...

static void SetDtorOnly (void *obj)
Set destructor only flag. More...

static void SetObjectStat (Bool_t stat)
Turn on/off tracking of objects in the TObjectTable. More...

#include <THelix.h>

Inheritance diagram for THelix:
[legend]

## ◆ THelix() [1/4]

 THelix::THelix ( )

Helix default constructor.

Definition at line 122 of file THelix.cxx.

## ◆ THelix() [2/4]

 THelix::THelix ( Double_t x, Double_t y, Double_t z, Double_t vx, Double_t vy, Double_t vz, Double_t w )

Helix normal constructor.

Definition at line 135 of file THelix.cxx.

## ◆ THelix() [3/4]

 THelix::THelix ( Double_t * xyz, Double_t * v, Double_t w, Double_t * range = 0, EHelixRangeType rtype = kHelixZ, Double_t * axis = 0 )

Helix normal constructor.

Definition at line 157 of file THelix.cxx.

## ◆ THelix() [4/4]

 THelix::THelix ( const THelix & helix )

Helix copy constructor.

Definition at line 236 of file THelix.cxx.

## ◆ ~THelix()

 THelix::~THelix ( )
virtual

Helix destructor.

Definition at line 227 of file THelix.cxx.

## ◆ Copy()

 void THelix::Copy ( TObject & helix ) const
virtual

Copy this helix to obj.

Reimplemented from TPolyLine3D.

Definition at line 246 of file THelix.cxx.

## ◆ Draw()

 void THelix::Draw ( Option_t * option = "" )
virtual

Draw this helix with its current attributes.

Reimplemented from TPolyLine3D.

Definition at line 280 of file THelix.cxx.

## ◆ FindClosestPhase()

 Double_t THelix::FindClosestPhase ( Double_t phi0, Double_t cosine )
protected

Finds the closest phase to phi0 that gives cos(phase) = cosine.

Definition at line 597 of file THelix.cxx.

## ◆ GetOption()

 Option_t * THelix::GetOption ( ) const
inlinevirtual

Reimplemented from TObject.

Definition at line 70 of file THelix.h.

## ◆ operator=()

 THelix & THelix::operator= ( const THelix & hx )
protected

assignment operator

Definition at line 204 of file THelix.cxx.

## ◆ Print()

 void THelix::Print ( Option_t * option = "" ) const
virtual

Dump this helix with its attributes.

Reimplemented from TPolyLine3D.

Definition at line 289 of file THelix.cxx.

## ◆ SavePrimitive()

 void THelix::SavePrimitive ( std::ostream & out, Option_t * option = "" )
virtual

Save primitive as a C++ statement(s) on output stream out.

Reimplemented from TPolyLine3D.

Definition at line 298 of file THelix.cxx.

## ◆ SetAxis() [1/2]

 void THelix::SetAxis ( Double_t * axis )
virtual

Set a new axis for the helix. This will make a new rotation matrix.

Definition at line 322 of file THelix.cxx.

## ◆ SetAxis() [2/2]

 void THelix::SetAxis ( Double_t x, Double_t y, Double_t z )
virtual

Set axis.

Definition at line 347 of file THelix.cxx.

## ◆ SetHelix()

 void THelix::SetHelix ( Double_t * xyz, Double_t * v, Double_t w, Double_t * range = 0, EHelixRangeType type = kUnchanged, Double_t * axis = 0 )

Set all helix parameters.

Definition at line 84 of file THelix.cxx.

## ◆ SetOption()

 virtual void THelix::SetOption ( Option_t * option = "" )
inlinevirtual

Reimplemented from TPolyLine3D.

Definition at line 73 of file THelix.h.

## ◆ SetRange() [1/2]

 void THelix::SetRange ( Double_t * range, EHelixRangeType rtype = kHelixZ )
virtual

Set a new range for the helix. This will remake the polyline.

Definition at line 357 of file THelix.cxx.

## ◆ SetRange() [2/2]

 void THelix::SetRange ( Double_t r1, Double_t r2, EHelixRangeType rtype = kHelixZ )
virtual

Set range.

Definition at line 550 of file THelix.cxx.

## ◆ SetRotMatrix()

 void THelix::SetRotMatrix ( )
protected

Set the rotational matrix according to the helix axis.

Definition at line 568 of file THelix.cxx.

## ◆ fAxis

 Double_t THelix::fAxis[3]
protected

Definition at line 46 of file THelix.h.

## ◆ fgMinNSeg

 Int_t THelix::fgMinNSeg =5
staticprotected

Definition at line 55 of file THelix.h.

## ◆ fPhi0

 Double_t THelix::fPhi0
protected

Definition at line 43 of file THelix.h.

## ◆ fRange

 Double_t THelix::fRange[2]
protected

Definition at line 48 of file THelix.h.

## ◆ fRotMat

 TRotMatrix* THelix::fRotMat
protected

Definition at line 47 of file THelix.h.

## ◆ fVt

 Double_t THelix::fVt
protected

Definition at line 42 of file THelix.h.

## ◆ fVz

 Double_t THelix::fVz
protected

Definition at line 44 of file THelix.h.

## ◆ fW

 Double_t THelix::fW
protected

Definition at line 45 of file THelix.h.

## ◆ fX0

 Double_t THelix::fX0
protected

Definition at line 39 of file THelix.h.

## ◆ fY0

 Double_t THelix::fY0
protected

Definition at line 40 of file THelix.h.

## ◆ fZ0

 Double_t THelix::fZ0
protected

Definition at line 41 of file THelix.h.

Libraries for THelix:
[legend]

The documentation for this class was generated from the following files: