G4ClassicalRK4 Class Reference

G4ClassicalRK4 integrates the equations of the motion of a particle in a magnetic field using the classical 4th Runge-Kutta method. More...

#include <G4ClassicalRK4.hh>

Inheritance diagram for G4ClassicalRK4:

Public Member Functions
	G4ClassicalRK4 (G4EquationOfMotion *EquationMotion, G4int numberOfVariables=6)
	~G4ClassicalRK4 () override
	G4ClassicalRK4 (const G4ClassicalRK4 &)=delete
G4ClassicalRK4 &	operator= (const G4ClassicalRK4 &)=delete
void	DumbStepper (const G4double yIn[], const G4double dydx[], G4double h, G4double yOut[]) override
G4int	IntegratorOrder () const override
G4StepperType	StepperType () const override
Public Member Functions inherited from G4MagErrorStepper
	G4MagErrorStepper (G4EquationOfMotion *EqRhs, G4int numberOfVariables, G4int numStateVariables=12)
	~G4MagErrorStepper () override
	G4MagErrorStepper (const G4MagErrorStepper &)=delete
G4MagErrorStepper &	operator= (const G4MagErrorStepper &)=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 G4MagIntegratorStepper
void	SetIntegrationOrder (G4int order)
void	SetFSAL (G4bool flag=true)

Detailed Description

G4ClassicalRK4 integrates the equations of the motion of a particle in a magnetic field using the classical 4th Runge-Kutta method.

Definition at line 45 of file G4ClassicalRK4.hh.

Constructor & Destructor Documentation

G4ClassicalRK4() [1/2]

G4ClassicalRK4::G4ClassicalRK4	(	G4EquationOfMotion *	EquationMotion,
		G4int	numberOfVariables = 6 )

Constructor for G4ClassicalRK4.

Parameters

[in]	EquationMotion	Pointer to the provided equation of motion.
[in]	numberOfVariables	The number of integration variables.

Definition at line 38 of file G4ClassicalRK4.cc.

  : G4MagErrorStepper(EqRhs, numberOfVariables)
{
   unsigned int noVariables= std::max(numberOfVariables,8); // For Time .. 7+1
 
   dydxm = new G4double[noVariables];
   dydxt = new G4double[noVariables]; 
   yt    = new G4double[noVariables]; 
}

Referenced by G4ClassicalRK4(), and operator=().

~G4ClassicalRK4()

G4ClassicalRK4::~G4ClassicalRK4 ( )

override

Destructor.

Definition at line 53 of file G4ClassicalRK4.cc.

{
  delete [] dydxm;
  delete [] dydxt;
  delete [] yt;
}

G4ClassicalRK4() [2/2]

G4ClassicalRK4::G4ClassicalRK4 ( const G4ClassicalRK4 & )

delete

Copy constructor and assignment operator not allowed.

Member Function Documentation

DumbStepper()

void G4ClassicalRK4::DumbStepper ( const G4double yIn[], const G4double dydx[], G4double h, G4double yOut[] )

overridevirtual

Given values for the variables y[0,..,n-1] and their derivatives dydx[0,...,n-1] known at x, uses the classical 4th Runge-Kutta method to advance the solution over an interval h and returns the incremented variables as yout[0,...,n-1]. The user supplies the function RightHandSide(x,y,dydx), which returns derivatives dydx at x. The source is routine rk4 from NRC p.712-713.

Parameters

[in]	yIn	Starting values array of integration variables.
[in]	dydx	Derivatives array.
[in]	h	The given step size.
[out]	yOut	Integration output.

Implements G4MagErrorStepper.

Definition at line 71 of file G4ClassicalRK4.cc.

{
  const G4int nvar = GetNumberOfVariables();   //  fNumberOfVariables(); 
  G4int i;
  G4double hh = h*0.5, h6 = h/6.0;
 
  // Initialise time to t0, needed when it is not updated by the integration.
  //        [ Note: Only for time dependent fields (usually electric) 
  //                  is it neccessary to integrate the time.] 
  yt[7]   = yIn[7]; 
  yOut[7] = yIn[7];
 
  for(i=0; i<nvar; ++i)
  {
    yt[i] = yIn[i] + hh*dydx[i] ;             // 1st Step K1=h*dydx
  }
  RightHandSide(yt,dydxt) ;                   // 2nd Step K2=h*dydxt
 
  for(i=0; i<nvar; ++i)
  { 
    yt[i] = yIn[i] + hh*dydxt[i] ;
  }
  RightHandSide(yt,dydxm) ;                   // 3rd Step K3=h*dydxm
 
  for(i=0; i<nvar; ++i)
  {
    yt[i] = yIn[i] + h*dydxm[i] ;
    dydxm[i] += dydxt[i] ;                    // now dydxm=(K2+K3)/h
  }
  RightHandSide(yt,dydxt) ;                   // 4th Step K4=h*dydxt
 
  for(i=0; i<nvar; ++i)    // Final RK4 output
  {
    yOut[i] = yIn[i]+h6*(dydx[i]+dydxt[i]+2.0*dydxm[i]); //+K1/6+K4/6+(K2+K3)/3
  }
  if ( nvar == 12 )  { NormalisePolarizationVector ( yOut ); }
  
}  // end of DumbStepper ....................................................

IntegratorOrder()

G4int G4ClassicalRK4::IntegratorOrder ( ) const

inlineoverridevirtual

Returns the order, 4, of integration.

Implements G4MagIntegratorStepper.

Definition at line 91 of file G4ClassicalRK4.hh.

{ return 4; }

operator=()

G4ClassicalRK4 & G4ClassicalRK4::operator= ( const G4ClassicalRK4 & )

delete

StepperType()

G4StepperType G4ClassicalRK4::StepperType ( ) const

inlineoverridevirtual

Returns the stepper type-ID, "kClassicalRK4".

Reimplemented from G4MagIntegratorStepper.

Definition at line 96 of file G4ClassicalRK4.hh.

{ return kClassicalRK4; }

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

• G4ClassicalRK4.hh
• G4ClassicalRK4.cc