Logo ROOT   6.19/01
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).

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

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();
}
pict1_THelix_001.png

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 (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...
 
 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 (const THelix &helix)
 Helix copy 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 (Int_t n, Option_t *option="")
 3-D polyline normal constructor with initialization to 0. More...
 
 TPolyLine3D (Int_t n, Float_t *p, Option_t *option="")
 3-D polyline normal constructor. More...
 
 TPolyLine3D (Int_t n, Double_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, Double_t *x, Double_t *y, Double_t *z, Option_t *option="")
 3-D polyline normal constructor. More...
 
 TPolyLine3D (const TPolyLine3D &polylin)
 3-D polyline copy ctor. More...
 
virtual ~TPolyLine3D ()
 3-D polyline destructor. 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 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 Int_t SetNextPoint (Double_t x, Double_t y, Double_t z)
 Set point following LastPoint to x, y, z. More...
 
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, Option_t *option="")
 Re-initialize polyline with n points (0,0,0). 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, Double_t *p, Option_t *option="")
 Re-initialize polyline with n points from p. 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...
 
virtual void AppendPad (Option_t *option="")
 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 Delete (Option_t *option="")
 Delete this object. 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 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 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
 
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 Pop ()
 Pop on object drawn in a pad to the top of the display list. 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...
 
void SetBit (UInt_t f, Bool_t set)
 Set or unset the user status bits as specified in f. More...
 
void SetBit (UInt_t f)
 
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
 

Additional Inherited Members

- Public Types inherited from TObject
enum  {
  kIsOnHeap = 0x01000000, kNotDeleted = 0x02000000, kZombie = 0x04000000, kInconsistent = 0x08000000,
  kBitMask = 0x00ffffff
}
 
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]

Constructor & Destructor Documentation

◆ 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.

Member Function Documentation

◆ 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.

Member Data Documentation

◆ 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: