#include <G4RKG3_Stepper.hh>

Inheritance diagram for G4RKG3_Stepper:

Collaboration diagram for G4RKG3_Stepper:

Public Member Functions
	G4RKG3_Stepper (G4Mag_EqRhs *EqRhs)

	~G4RKG3_Stepper ()

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

G4double	DistChord () const

void	StepNoErr (const G4double tIn[8], const G4double dydx[6], G4double Step, G4double tOut[8], G4double B[3])

void	StepWithEst (const G4double tIn[8], const G4double dydx[6], G4double Step, G4double tOut[8], G4double &alpha2, G4double &beta2, const G4double B1[3], G4double B2[3])

G4int	IntegratorOrder () const

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

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

G4int	IntegrationOrder ()

G4EquationOfMotion *	GetEquationOfMotion ()

void	SetEquationOfMotion (G4EquationOfMotion *newEquation)

unsigned long	GetfNoRHSCalls ()

void	ResetfNORHSCalls ()

bool	IsFSAL ()

Additional Inherited Members
Protected Member Functions inherited from G4MagIntegratorStepper
void	SetIntegrationOrder (int order)

void	SetFSAL (bool flag=true)

Detailed Description

Definition at line 51 of file G4RKG3_Stepper.hh.

Constructor & Destructor Documentation

G4RKG3_Stepper::G4RKG3_Stepper ( G4Mag_EqRhs * EqRhs )

Definition at line 35 of file G4RKG3_Stepper.cc.

   : G4MagIntegratorStepper(EqRhs,6), hStep(0.)
 {
 }

G4RKG3_Stepper::~G4RKG3_Stepper ( )

Definition at line 40 of file G4RKG3_Stepper.cc.

41 {

42 }

Member Function Documentation

G4double G4RKG3_Stepper::DistChord ( ) const

virtual

Implements G4MagIntegratorStepper.

Definition at line 197 of file G4RKG3_Stepper.cc.

  {
    // Soon: must check whether h/R > 2 pi  !!
    //  Method below is good only for < 2 pi
    G4double distChord,distLine;
    
    if (fyInitial != fyFinal) {
       distLine= G4LineSection::Distline(fyMidPoint,fyInitial,fyFinal );
   
         distChord = distLine;
    }else{
       distChord = (fyMidPoint-fyInitial).mag();
    }
  
   
    return distChord;
    
  }

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G4int G4RKG3_Stepper::IntegratorOrder ( ) const

inlinevirtual

Implements G4MagIntegratorStepper.

Definition at line 95 of file G4RKG3_Stepper.hh.

95 { return 4; }

void G4RKG3_Stepper::StepNoErr	(	const G4double	tIn[8],
		const G4double	dydx[6],
		G4double	Step,
		G4double	tOut[8],
		G4double	B[3]
	)

Definition at line 126 of file G4RKG3_Stepper.cc.

 { 
   
   //  Copy and edit the routine above, to delete alpha2, beta2, ...
    G4double K1[7],K2[7],K3[7],K4[7] ;
    G4double tTemp[8], yderiv[6] ;
 
   // Need Momentum value to give correct values to the coefficients in equation
   // Integration on unit velocity, but  tIn[3,4,5] is momentum 
    G4double mom,inverse_mom;
    G4int i ;
    const G4double c1=0.5,c2=0.125,c3=1./6.;
   
    // GetEquationOfMotion()->EvaluateRhsReturnB(tIn,dydx,B1) ;
    // Correction for momentum not a velocity
    // Need the protection !!! must be not zero 
      mom=std::sqrt(tIn[3]*tIn[3]+tIn[4]*tIn[4]+tIn[5]*tIn[5]); 
      inverse_mom=1./mom;    
    for(i=0;i<3;i++)
    {
       K1[i] = Step * dydx[i+3]*inverse_mom;
       tTemp[i] = tIn[i] + Step*(c1*tIn[i+3]*inverse_mom + c2*K1[i]) ;
       tTemp[i+3] = tIn[i+3] + c1*K1[i]*mom ;
      
    }
     
    GetEquationOfMotion()->EvaluateRhsReturnB(tTemp,yderiv,B) ;
     
       
    for(i=0;i<3;i++)
    {
       K2[i] = Step * yderiv[i+3]*inverse_mom;
       tTemp[i+3] = tIn[i+3] + c1*K2[i]*mom ;
    }
    
    //  Given B, calculate yderiv !
    GetEquationOfMotion()->EvaluateRhsGivenB(tTemp,B,yderiv) ;  
  
    for(i=0;i<3;i++)
    {
       K3[i] = Step * yderiv[i+3]*inverse_mom;
       tTemp[i] = tIn[i] + Step*(tIn[i+3]*inverse_mom + c1*K3[i]) ;
       tTemp[i+3] = tIn[i+3] + K3[i]*mom ;
    }
    
 
    //  Calculates y-deriv(atives) & returns B too!
    GetEquationOfMotion()->EvaluateRhsReturnB(tTemp,yderiv,B) ;  
     
 
    for(i=0;i<3;i++)        // Output trajectory vector
    {
       K4[i] = Step * yderiv[i+3]*inverse_mom;
       tOut[i] = tIn[i] + Step*(tIn[i+3]*inverse_mom+ (K1[i] + K2[i] + K3[i])*c3) ;
       tOut[i+3] = tIn[i+3] + mom*(K1[i] + 2*K2[i] + 2*K3[i] +K4[i])*c3 ;
    }
    tOut[6] = tIn[6];
    tOut[7] = tIn[7];
    // NormaliseTangentVector( tOut );
   
 
 }

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void G4RKG3_Stepper::Stepper	(	const G4double	yIn[],
		const G4double	dydx[],
		G4double	h,
		G4double	yOut[],
		G4double	yErr[]
	)

virtual

Implements G4MagIntegratorStepper.

Definition at line 44 of file G4RKG3_Stepper.cc.

 {
    G4double  B[3];
    G4int nvar = 6 ;
    G4int i;
    G4double  by15 = 1. / 15. ; // was  0.066666666 ;
 
    G4double yTemp[8], dydxTemp[6], yIn[8] ;
    //  Saving yInput because yInput and yOut can be aliases for same array
    for(i=0;i<nvar;i++) yIn[i]=yInput[i];
    yIn[6] = yInput[6];
    yIn[7] = yInput[7];
    G4double h = Step * 0.5; 
    hStep=Step;
    // Do two half steps
 
    StepNoErr(yIn, dydx,h, yTemp,B) ;
    
    //Store Bfld for DistChord Calculation
    for(i=0;i<3;i++)BfldIn[i]=B[i];
 
    //   RightHandSide(yTemp,dydxTemp) ;
 
    GetEquationOfMotion()->EvaluateRhsGivenB(yTemp,B,dydxTemp) ;  
    StepNoErr(yTemp,dydxTemp,h,yOut,B);      
         
    // Store midpoint, chord calculation
                                  
    fyMidPoint = G4ThreeVector( yTemp[0],  yTemp[1],  yTemp[2]); 
 
    // Do a full Step
 
    h *= 2 ;
    StepNoErr(yIn,dydx,h,yTemp,B); 
    for(i=0;i<nvar;i++)
    {
       yErr[i] = yOut[i] - yTemp[i] ;
       yOut[i] += yErr[i]*by15 ;          // Provides 5th order of accuracy
    }
 
    //Store values for DistChord method
 
    fyInitial = G4ThreeVector( yIn[0],   yIn[1],   yIn[2]);
    fpInitial = G4ThreeVector( yIn[3],   yIn[4],   yIn[5]);
    fyFinal   = G4ThreeVector( yOut[0],  yOut[1],  yOut[2]); 
   
    // NormaliseTangentVector( yOut );  // Deleted
 }

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void G4RKG3_Stepper::StepWithEst	(	const G4double	tIn[8],
		const G4double	dydx[6],
		G4double	Step,
		G4double	tOut[8],
		G4double &	alpha2,
		G4double &	beta2,
		const G4double	B1[3],
		G4double	B2[3]
	)

Definition at line 104 of file G4RKG3_Stepper.cc.

 {
   G4Exception("G4RKG3_Stepper::StepWithEst()", "GeomField0001",
               FatalException, "Method no longer used.");
 }

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

geant4.10.03.p01/source/geometry/magneticfield/include/G4RKG3_Stepper.hh
geant4.10.03.p01/source/geometry/magneticfield/src/G4RKG3_Stepper.cc

Public Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation