G4ConstRK4 Class Reference

#include <G4ConstRK4.hh>

Inheritance diagram for G4ConstRK4:

Public Member Functions
	G4ConstRK4 (G4Mag_EqRhs *EquationMotion, G4int numberOfStateVariables=8)
	~G4ConstRK4 () override
	G4ConstRK4 (const G4ConstRK4 &)=delete
G4ConstRK4 &	operator= (const G4ConstRK4 &)=delete
void	Stepper (const G4double y[], const G4double dydx[], G4double h, G4double yout[], G4double yerr[]) override
void	DumbStepper (const G4double yIn[], const G4double dydx[], G4double h, G4double yOut[]) override
G4double	DistChord () const override
void	RightHandSideConst (const G4double y[], G4double dydx[]) const
void	GetConstField (const G4double y[], G4double Field[])
G4int	IntegratorOrder () 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

Definition at line 45 of file G4ConstRK4.hh.

Constructor & Destructor Documentation

G4ConstRK4() [1/2]

G4ConstRK4::G4ConstRK4	(	G4Mag_EqRhs *	EquationMotion,
		G4int	numberOfStateVariables = 8 )

Definition at line 40 of file G4ConstRK4.cc.

  : G4MagErrorStepper(EqRhs, 6, numStateVariables)
{
  // const G4int numberOfVariables= 6;
  if( numStateVariables < 8 ) 
  {
    std::ostringstream message;
    message << "The number of State variables at least 8 " << G4endl
            << "Instead it is - numStateVariables= " << numStateVariables;
    G4Exception("G4ConstRK4::G4ConstRK4()", "GeomField0002",
                FatalException, message, "Use another Stepper!");
  }
 
  fEq = EqRhs;
  yMiddle  = new G4double[8];
  dydxMid  = new G4double[8];
  yInitial = new G4double[8];
  yOneStep = new G4double[8];
 
  dydxm = new G4double[8];
  dydxt = new G4double[8]; 
  yt    = new G4double[8]; 
  Field[0]=0.; Field[1]=0.; Field[2]=0.;
}

~G4ConstRK4()

G4ConstRK4::~G4ConstRK4 ( )

override

Definition at line 69 of file G4ConstRK4.cc.

{
   delete [] yMiddle;
   delete [] dydxMid;
   delete [] yInitial;
   delete [] yOneStep;
   delete [] dydxm;
   delete [] dydxt;
   delete [] yt;
}

G4ConstRK4() [2/2]

G4ConstRK4::G4ConstRK4 ( const G4ConstRK4 & )

delete

Member Function Documentation

DistChord()

G4double G4ConstRK4::DistChord ( ) const

overridevirtual

Implements G4MagIntegratorStepper.

Definition at line 211 of file G4ConstRK4.cc.

{
  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()

void G4ConstRK4::DumbStepper ( const G4double yIn[], const G4double dydx[], G4double h, G4double yOut[] )

overridevirtual

Implements G4MagErrorStepper.

Definition at line 90 of file G4ConstRK4.cc.

{
   G4double  hh = h*0.5 , h6 = h/6.0  ;
   
   // 1st Step K1=h*dydx
   yt[5] = yIn[5] + hh*dydx[5] ;
   yt[4] = yIn[4] + hh*dydx[4] ;
   yt[3] = yIn[3] + hh*dydx[3] ;
   yt[2] = yIn[2] + hh*dydx[2] ;
   yt[1] = yIn[1] + hh*dydx[1] ;
   yt[0] = yIn[0] + hh*dydx[0] ;
   RightHandSideConst(yt,dydxt) ;        
 
   // 2nd Step K2=h*dydxt
   yt[5] = yIn[5] + hh*dydxt[5] ;
   yt[4] = yIn[4] + hh*dydxt[4] ;
   yt[3] = yIn[3] + hh*dydxt[3] ;
   yt[2] = yIn[2] + hh*dydxt[2] ;
   yt[1] = yIn[1] + hh*dydxt[1] ;
   yt[0] = yIn[0] + hh*dydxt[0] ;
   RightHandSideConst(yt,dydxm) ;     
 
   // 3rd Step K3=h*dydxm
   // now dydxm=(K2+K3)/h
   yt[5] = yIn[5] + h*dydxm[5] ;
   dydxm[5] += dydxt[5] ;  
   yt[4] = yIn[4] + h*dydxm[4] ;
   dydxm[4] += dydxt[4] ;  
   yt[3] = yIn[3] + h*dydxm[3] ;
   dydxm[3] += dydxt[3] ;  
   yt[2] = yIn[2] + h*dydxm[2] ;
   dydxm[2] += dydxt[2] ;  
   yt[1] = yIn[1] + h*dydxm[1] ;
   dydxm[1] += dydxt[1] ;  
   yt[0] = yIn[0] + h*dydxm[0] ;
   dydxm[0] += dydxt[0] ;  
   RightHandSideConst(yt,dydxt) ;   
 
   // 4th Step K4=h*dydxt
   yOut[5] = yIn[5]+h6*(dydx[5]+dydxt[5]+2.0*dydxm[5]);
   yOut[4] = yIn[4]+h6*(dydx[4]+dydxt[4]+2.0*dydxm[4]);
   yOut[3] = yIn[3]+h6*(dydx[3]+dydxt[3]+2.0*dydxm[3]);
   yOut[2] = yIn[2]+h6*(dydx[2]+dydxt[2]+2.0*dydxm[2]);
   yOut[1] = yIn[1]+h6*(dydx[1]+dydxt[1]+2.0*dydxm[1]);
   yOut[0] = yIn[0]+h6*(dydx[0]+dydxt[0]+2.0*dydxm[0]);
   
}  // end of DumbStepper ....................................................

Referenced by Stepper().

GetConstField()

void G4ConstRK4::GetConstField ( const G4double y[], G4double Field[] )

inline

Definition at line 104 of file G4ConstRK4.hh.

{
  G4double PositionAndTime[4];
 
  PositionAndTime[0] = y[0];
  PositionAndTime[1] = y[1];
  PositionAndTime[2] = y[2];
  // Global Time
  PositionAndTime[3] = y[7];
  fEq -> GetFieldValue(PositionAndTime, B);
}

Referenced by Stepper().

IntegratorOrder()

G4int G4ConstRK4::IntegratorOrder ( ) const

inlineoverridevirtual

Implements G4MagIntegratorStepper.

Definition at line 72 of file G4ConstRK4.hh.

{ return 4; }

Referenced by Stepper().

operator=()

G4ConstRK4 & G4ConstRK4::operator= ( const G4ConstRK4 & )

delete

RightHandSideConst()

void G4ConstRK4::RightHandSideConst ( const G4double y[], G4double dydx[] ) const

inline

Definition at line 86 of file G4ConstRK4.hh.

{
  
  G4double momentum_mag_square = y[3]*y[3] + y[4]*y[4] + y[5]*y[5];
  G4double inv_momentum_magnitude = 1.0 / std::sqrt( momentum_mag_square );
    
  G4double cof = fEq->FCof()*inv_momentum_magnitude;
 
  dydx[0] = y[3]*inv_momentum_magnitude;       //  (d/ds)x = Vx/V
  dydx[1] = y[4]*inv_momentum_magnitude;       //  (d/ds)y = Vy/V
  dydx[2] = y[5]*inv_momentum_magnitude;       //  (d/ds)z = Vz/V
 
  dydx[3] = cof*(y[4]*Field[2] - y[5]*Field[1]) ;   // Ax = a*(Vy*Bz - Vz*By)
  dydx[4] = cof*(y[5]*Field[0] - y[3]*Field[2]) ;   // Ay = a*(Vz*Bx - Vx*Bz)
  dydx[5] = cof*(y[3]*Field[1] - y[4]*Field[0]) ;   // Az = a*(Vx*By - Vy*Bx)
}

Referenced by DumbStepper(), and Stepper().

Stepper()

void G4ConstRK4::Stepper ( const G4double y[], const G4double dydx[], G4double h, G4double yout[], G4double yerr[] )

overridevirtual

Implements G4MagIntegratorStepper.

Definition at line 146 of file G4ConstRK4.cc.

{
   const G4int nvar = 6;  // number of variables integrated
   const G4int maxvar = GetNumberOfStateVariables();
 
   // Correction for Richardson extrapolation
   G4double  correction = 1. / ( (1 << IntegratorOrder()) -1 );
 
   G4int i;
   
   // Saving yInput because yInput and yOutput can be aliases for same array
   for (i=0;    i<maxvar; ++i) { yInitial[i]= yInput[i]; }
 
   // Must copy the part of the state *not* integrated to the output
   for (i=nvar; i<maxvar; ++i) { yOutput[i]=  yInput[i]; }
 
   // yInitial[7]= yInput[7];  //  The time is typically 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
   yError[7] = 0.0;         
 
   G4double halfStep = hstep * 0.5; 
 
   // Do two half steps
   //
   GetConstField(yInitial,Field);
   DumbStepper  (yInitial,  dydx,   halfStep, yMiddle);
   RightHandSideConst(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(i=0; i<nvar; ++i)
   {
      yError [i] = yOutput[i] - yOneStep[i] ;
      yOutput[i] += yError[i]*correction ;
        // Provides accuracy increased by 1 order via the 
        // 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:

• G4ConstRK4.hh
• G4ConstRK4.cc