G4ExactHelixStepper Class Reference

G4ExactHelixStepper is a concrete class for particle motion in constant magnetic field. Helix a-la-Explicity Euler: x_1 = x_0 + helix(h) with helix(h) being a helix piece of length h. As the field is assumed constant, an error is not calculated. More...

#include <G4ExactHelixStepper.hh>

Inheritance diagram for G4ExactHelixStepper:

Public Member Functions
	G4ExactHelixStepper (G4Mag_EqRhs *EqRhs)
	~G4ExactHelixStepper () override=default
	G4ExactHelixStepper (const G4ExactHelixStepper &)=delete
G4ExactHelixStepper &	operator= (const G4ExactHelixStepper &)=delete
void	Stepper (const G4double y[], const G4double dydx[], G4double h, G4double yout[], G4double yerr[]) override
void	DumbStepper (const G4double y[], G4ThreeVector Bfld, G4double h, G4double yout[]) override
G4double	DistChord () const override
G4int	IntegratorOrder () const override
G4StepperType	StepperType () const override
Public Member Functions inherited from G4MagHelicalStepper
	G4MagHelicalStepper (G4Mag_EqRhs *EqRhs)
	~G4MagHelicalStepper () override=default
	G4MagHelicalStepper (const G4MagHelicalStepper &)=delete
G4MagHelicalStepper &	operator= (const G4MagHelicalStepper &)=delete
void	Stepper (const G4double y[], const G4double dydx[], G4double h, G4double yout[], G4double yerr[]) override
G4double	DistChord () const override
Public Member Functions inherited from G4MagIntegratorStepper
	G4MagIntegratorStepper (G4EquationOfMotion *Equation, G4int numIntegrationVariables, G4int numStateVariables=12, G4bool isFSAL=false)
virtual	~G4MagIntegratorStepper ()=default
	G4MagIntegratorStepper (const G4MagIntegratorStepper &)=delete
G4MagIntegratorStepper &	operator= (const G4MagIntegratorStepper &)=delete
void	NormaliseTangentVector (G4double vec[6])
void	NormalisePolarizationVector (G4double vec[12])
void	RightHandSide (const G4double y[], G4double dydx[]) const
void	RightHandSide (const G4double y[], G4double dydx[], G4double field[]) const
G4int	GetNumberOfVariables () const
G4int	GetNumberOfStateVariables () const
G4int	IntegrationOrder ()
G4EquationOfMotion *	GetEquationOfMotion ()
const G4EquationOfMotion *	GetEquationOfMotion () const
void	SetEquationOfMotion (G4EquationOfMotion *newEquation)
unsigned long	GetfNoRHSCalls ()
void	ResetfNORHSCalls ()
G4bool	IsFSAL () const
G4bool	isQSS () const
void	SetIsQSS (G4bool val)

Additional Inherited Members
Protected Member Functions inherited from G4MagHelicalStepper
void	LinearStep (const G4double yIn[], G4double h, G4double yHelix[]) const
void	AdvanceHelix (const G4double yIn[], const G4ThreeVector &Bfld, G4double h, G4double yHelix[], G4double yHelix2[]=nullptr)
void	MagFieldEvaluate (const G4double y[], G4ThreeVector &Bfield)
G4double	GetInverseCurve (const G4double Momentum, const G4double Bmag)
void	SetAngCurve (const G4double Ang)
G4double	GetAngCurve () const
void	SetCurve (const G4double Curve)
G4double	GetCurve () const
void	SetRadHelix (const G4double Rad)
G4double	GetRadHelix () const
Protected Member Functions inherited from G4MagIntegratorStepper
void	SetIntegrationOrder (G4int order)
void	SetFSAL (G4bool flag=true)

Detailed Description

G4ExactHelixStepper is a concrete class for particle motion in constant magnetic field. Helix a-la-Explicity Euler: x_1 = x_0 + helix(h) with helix(h) being a helix piece of length h. As the field is assumed constant, an error is not calculated.

Definition at line 58 of file G4ExactHelixStepper.hh.

Constructor & Destructor Documentation

G4ExactHelixStepper() [1/2]

G4ExactHelixStepper::G4ExactHelixStepper

(

G4Mag_EqRhs *

EqRhs

)

Constructor for G4ExactHelixStepper.

Parameters

[in]

EqRhs

Pointer to the standard equation of motion.

Definition at line 37 of file G4ExactHelixStepper.cc.

  : G4MagHelicalStepper(EqRhs),
    fBfieldValue(DBL_MAX, DBL_MAX, DBL_MAX)
{
}

Referenced by G4ExactHelixStepper(), and operator=().

~G4ExactHelixStepper()

G4ExactHelixStepper::~G4ExactHelixStepper ( )

overridedefault

Default Destructor.

G4ExactHelixStepper() [2/2]

G4ExactHelixStepper::G4ExactHelixStepper ( const G4ExactHelixStepper & )

delete

Copy constructor and assignment operator not allowed.

Member Function Documentation

DistChord()

G4double G4ExactHelixStepper::DistChord ( ) const

overridevirtual

Estimates the maximum distance of curved solution and chord.

Implements G4MagIntegratorStepper.

Definition at line 91 of file G4ExactHelixStepper.cc.

{
  // Implementation : must check whether h/R >  pi  !!
  //   If( h/R <  pi)   DistChord=h/2*std::tan(Ang_curve/4)
  //   Else             DistChord=R_helix
 
  G4double distChord;
  G4double Ang_curve=GetAngCurve();
 
  if (Ang_curve<=pi)
  {
    distChord=GetRadHelix()*(1-std::cos(0.5*Ang_curve));
  }
  else if(Ang_curve<twopi)
  {
    distChord=GetRadHelix()*(1+std::cos(0.5*(twopi-Ang_curve)));
  }
  else
  {
    distChord=2.*GetRadHelix();  
  }
 
  return distChord;
}   

DumbStepper()

void G4ExactHelixStepper::DumbStepper ( const G4double y[], G4ThreeVector Bfld, G4double h, G4double yout[] )

overridevirtual

Same as Stepper() function above, but should perform a 'dump' step without error calculation. Assuming a constant field, the solution is a helix. Should NOT be called; issues a fatal exception as the Stepper must do all the work.

Implements G4MagHelicalStepper.

Definition at line 73 of file G4ExactHelixStepper.cc.

{
  // Assuming a constant field: solution is a helix
 
  AdvanceHelix(yIn, Bfld, h, yOut);
 
  G4Exception("G4ExactHelixStepper::DumbStepper",
              "GeomField0002", FatalException,
              "Should not be called. Stepper must do all the work." ); 
}  

IntegratorOrder()

G4int G4ExactHelixStepper::IntegratorOrder ( ) const

inlineoverridevirtual

Returns the order, 1, of integration.

Implements G4MagIntegratorStepper.

Definition at line 115 of file G4ExactHelixStepper.hh.

{ return 1; }

operator=()

G4ExactHelixStepper & G4ExactHelixStepper::operator= ( const G4ExactHelixStepper & )

delete

Stepper()

void G4ExactHelixStepper::Stepper ( const G4double y[], const G4double dydx[], G4double h, G4double yout[], G4double yerr[] )

overridevirtual

The stepper for the Runge Kutta integration. The stepsize is fixed, with the step size given by 'h'. Provides helix starting values y[0 to 6]. Outputs yout[] and ZERO estimated error yerr[]=0.

Parameters

[in]	yInput	Starting values array of integration variables.
[in]	dydx	Derivatives array.
[in]	h	The given step size.
[out]	yout	Integration output.
[out]	yerr	The estimated error.

Implements G4MagIntegratorStepper.

Definition at line 46 of file G4ExactHelixStepper.cc.

{  
  const G4int nvar = 6;
 
  G4int i;
  G4ThreeVector Bfld_value;
 
  MagFieldEvaluate(yInput, Bfld_value);        
  AdvanceHelix(yInput, Bfld_value, hstep, yOut);
 
  // We are assuming a constant field: helix is exact
  //
  for(i=0; i<nvar; ++i)
  {
    yErr[i] = 0.0 ;
  }
 
  fBfieldValue = Bfld_value;
}

StepperType()

G4StepperType G4ExactHelixStepper::StepperType ( ) const

inlineoverridevirtual

Returns the stepper type-ID, "kExactHelixStepper".

Reimplemented from G4MagIntegratorStepper.

Definition at line 120 of file G4ExactHelixStepper.hh.

{ return kExactHelixStepper; }

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

• G4ExactHelixStepper.hh
• G4ExactHelixStepper.cc