#include <G4ConstRK4.hh>

Inheritance diagram for G4ConstRK4:

Collaboration diagram for G4ConstRK4:

Public Member Functions
	G4ConstRK4 (G4Mag_EqRhs *EquationMotion, G4int numberOfStateVariables=8)

	~G4ConstRK4 ()

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

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

G4double	DistChord () const

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

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

G4int	IntegratorOrder () const

Public Member Functions inherited from G4MagErrorStepper
	G4MagErrorStepper (G4EquationOfMotion *EqRhs, G4int numberOfVariables, G4int numStateVariables=12)

virtual	~G4MagErrorStepper ()

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

G4double	DistChord () const

Public Member Functions inherited from G4MagIntegratorStepper
	G4MagIntegratorStepper (G4EquationOfMotion *Equation, G4int numIntegrationVariables, G4int numStateVariables=12)

virtual	~G4MagIntegratorStepper ()

virtual void	ComputeRightHandSide (const G4double y[], G4double dydx[])

void	NormaliseTangentVector (G4double vec[6])

void	NormalisePolarizationVector (G4double vec[12])

void	RightHandSide (const double y[], double dydx[])

G4int	GetNumberOfVariables () const

G4int	GetNumberOfStateVariables () const

G4EquationOfMotion *	GetEquationOfMotion ()

void	SetEquationOfMotion (G4EquationOfMotion *newEquation)

Private Member Functions
	G4ConstRK4 (const G4ConstRK4 &)

G4ConstRK4 &	operator= (const G4ConstRK4 &)

Private Attributes
G4ThreeVector	fInitialPoint

G4ThreeVector	fMidPoint

G4ThreeVector	fFinalPoint

G4double *	dydxm

G4double *	dydxt

G4double *	yt

G4double *	yInitial

G4double *	yMiddle

G4double *	dydxMid

G4double *	yOneStep

G4Mag_EqRhs *	fEq

G4double	Field [3]

Detailed Description

Definition at line 51 of file G4ConstRK4.hh.

Constructor & Destructor Documentation

◆ G4ConstRK4() [1/2]

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

Definition at line 42 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.;
 }

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◆ ~G4ConstRK4()

G4ConstRK4::~G4ConstRK4 ( )

Definition at line 71 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 & )

private

Member Function Documentation

◆ DistChord()

G4double G4ConstRK4::DistChord ( ) const

virtual

Implements G4MagIntegratorStepper.

Definition at line 213 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;
 }

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◆ DumbStepper()

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

virtual

Implements G4MagErrorStepper.

Definition at line 92 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 ....................................................

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◆ GetConstField()

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

inline

Definition at line 114 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) ;
 }

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◆ IntegratorOrder()

G4int G4ConstRK4::IntegratorOrder ( ) const

inlinevirtual

Implements G4MagIntegratorStepper.

Definition at line 76 of file G4ConstRK4.hh.

76 { return 4; }

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◆ operator=()

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

private

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◆ RightHandSideConst()

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

inline

Definition at line 96 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)
 }

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◆ Stepper()

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

virtual

Implements G4MagIntegratorStepper.

Definition at line 148 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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Member Data Documentation

◆ dydxm

G4double* G4ConstRK4::dydxm

private

Definition at line 88 of file G4ConstRK4.hh.

◆ dydxMid

G4double * G4ConstRK4::dydxMid

private

Definition at line 89 of file G4ConstRK4.hh.

◆ dydxt

G4double * G4ConstRK4::dydxt

private

Definition at line 88 of file G4ConstRK4.hh.

◆ fEq

G4Mag_EqRhs* G4ConstRK4::fEq

private

Definition at line 90 of file G4ConstRK4.hh.

◆ fFinalPoint

G4ThreeVector G4ConstRK4::fFinalPoint

private

Definition at line 86 of file G4ConstRK4.hh.

◆ Field

G4double G4ConstRK4::Field[3]

private

Definition at line 91 of file G4ConstRK4.hh.

◆ fInitialPoint

G4ThreeVector G4ConstRK4::fInitialPoint

private

Definition at line 86 of file G4ConstRK4.hh.

◆ fMidPoint

G4ThreeVector G4ConstRK4::fMidPoint

private

Definition at line 86 of file G4ConstRK4.hh.

◆ yInitial

G4double* G4ConstRK4::yInitial

private

Definition at line 89 of file G4ConstRK4.hh.

◆ yMiddle

G4double * G4ConstRK4::yMiddle

private

Definition at line 89 of file G4ConstRK4.hh.

◆ yOneStep

G4double * G4ConstRK4::yOneStep

private

Definition at line 89 of file G4ConstRK4.hh.

◆ yt

G4double * G4ConstRK4::yt

private

Definition at line 88 of file G4ConstRK4.hh.

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

Public Member Functions

Private Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ G4ConstRK4() [1/2]

◆ ~G4ConstRK4()

◆ G4ConstRK4() [2/2]

Member Function Documentation

◆ DistChord()

◆ DumbStepper()

◆ GetConstField()

◆ IntegratorOrder()

◆ operator=()

◆ RightHandSideConst()

◆ Stepper()

Member Data Documentation

◆ dydxm

◆ dydxMid

◆ dydxt

◆ fEq

◆ fFinalPoint

◆ Field

◆ fInitialPoint

◆ fMidPoint

◆ yInitial

◆ yMiddle

◆ yOneStep

◆ yt