G4MagErrorStepper Class Reference

G4MagErrorStepper is an abstract base class for integrator of particle's equation of motion, used in tracking in space dependent magnetic field. More...

#include <G4MagErrorStepper.hh>

Inheritance diagram for G4MagErrorStepper:

Public Member Functions
	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
virtual void	DumbStepper (const G4double y[], const G4double dydx[], G4double h, G4double yout[])=0
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
virtual G4int	IntegratorOrder () const =0
virtual G4StepperType	StepperType () 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

G4MagErrorStepper is an abstract base class for integrator of particle's equation of motion, used in tracking in space dependent magnetic field.

Definition at line 49 of file G4MagErrorStepper.hh.

Constructor & Destructor Documentation

G4MagErrorStepper() [1/2]

G4MagErrorStepper::G4MagErrorStepper	(	G4EquationOfMotion *	EqRhs,
		G4int	numberOfVariables,
		G4int	numStateVariables = 12 )

Constructor for G4MagErrorStepper.

Parameters

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

Referenced by G4ClassicalRK4::G4ClassicalRK4(), G4ConstRK4::G4ConstRK4(), G4ExplicitEuler::G4ExplicitEuler(), G4ImplicitEuler::G4ImplicitEuler(), G4MagErrorStepper(), G4SimpleHeum::G4SimpleHeum(), G4SimpleRunge::G4SimpleRunge(), and operator=().

~G4MagErrorStepper()

G4MagErrorStepper::~G4MagErrorStepper ( )

override

Destructor.

Definition at line 34 of file G4MagErrorStepper.cc.

{
   delete [] yMiddle;
   delete [] dydxMid;
   delete [] yInitial;
   delete [] yOneStep;
}

G4MagErrorStepper() [2/2]

G4MagErrorStepper::G4MagErrorStepper ( const G4MagErrorStepper & )

delete

Copy constructor and assignment operator not allowed.

Member Function Documentation

DistChord()

G4double G4MagErrorStepper::DistChord ( ) const

overridevirtual

Estimates the maximum distance of curved solution and chord.

Implements G4MagIntegratorStepper.

Definition at line 100 of file G4MagErrorStepper.cc.

{
  // Estimate the maximum distance from the curve to the chord
  //
  // We estimate this using the distance of the midpoint to 
  // chord (the line between 
  // 
  // Method below is good only for angle deviations < 2 pi, 
  // This restriction should not a problem for the Runge cutta methods, 
  // which generally cannot integrate accurately for large angle deviations.
 
  G4double distLine, distChord; 
 
  if (fInitialPoint != fFinalPoint)
  {
     distLine = G4LineSection::Distline(fMidPoint, fInitialPoint, fFinalPoint);
       // This is a class method that gives distance of Mid 
       // from the Chord between the Initial and Final points.
 
     distChord = distLine;
  }
  else
  {
     distChord = (fMidPoint-fInitialPoint).mag();
  }
 
  return distChord;
}

DumbStepper()

virtual void G4MagErrorStepper::DumbStepper ( const G4double y[], const G4double dydx[], G4double h, G4double yout[] )

pure virtual

Same as Stepper() function above, but should perform a 'dump' step without error calculation. To be implemented in concrete derived classes.

Implemented in G4ClassicalRK4, G4ConstRK4, G4ExplicitEuler, G4ImplicitEuler, G4SimpleHeum, and G4SimpleRunge.

Referenced by Stepper().

operator=()

G4MagErrorStepper & G4MagErrorStepper::operator= ( const G4MagErrorStepper & )

delete

Stepper()

void G4MagErrorStepper::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'. Integrates ODE starting values y[0 to 6]. Outputs yout[] and its estimated error yerr[].

Parameters

[in]	y	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 42 of file G4MagErrorStepper.cc.

{  
   const G4int nvar = GetNumberOfVariables();
   const G4int maxvar = GetNumberOfStateVariables();
 
   // correction for Richardson Extrapolation.
   //
   G4double  correction = 1. / ( (1 << IntegratorOrder()) -1 );
   
   //  Saving yInput because yInput and yOutput can be aliases for same array
   //
   for(G4int i=0; i<nvar; ++i)
   {
     yInitial[i]=yInput[i];
   }
   yInitial[7] = yInput[7]; // Copy the time in case...even if not really needed
   yMiddle[7] = yInput[7];  // Copy the time from initial value 
   yOneStep[7] = yInput[7]; // As it contributes to final value of yOutput ?
   // yOutput[7] = yInput[7];  // -> dumb stepper does it too for RK4
 
   for(G4int i=nvar; i<maxvar; ++i)
   {
     yOutput[i]=yInput[i];
   }
   // yError[7] = 0.0;         
 
   G4double halfStep = hstep * 0.5; 
 
   // Do two half steps
   //
   DumbStepper  (yInitial,  dydx,   halfStep, yMiddle);
   RightHandSide(yMiddle, dydxMid);    
   DumbStepper  (yMiddle, dydxMid, halfStep, yOutput); 
 
   // Store midpoint, chord calculation
   //
   fMidPoint = G4ThreeVector( yMiddle[0],  yMiddle[1],  yMiddle[2]); 
 
   // Do a full Step
   //
   DumbStepper(yInitial, dydx, hstep, yOneStep);
   for(G4int i=0; i<nvar; ++i)
   {
      yError [i] = yOutput[i] - yOneStep[i] ;
      yOutput[i] += yError[i]*correction ;
        // Provides accuracy increased by 1 order via Richardson Extrapolation  
   }
 
   fInitialPoint = G4ThreeVector( yInitial[0], yInitial[1], yInitial[2]); 
   fFinalPoint   = G4ThreeVector( yOutput[0],  yOutput[1],  yOutput[2]); 
 
   return;
}

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

• G4MagErrorStepper.hh
• G4MagErrorStepper.cc