G4CashKarpRKF45 Class Reference

#include <G4CashKarpRKF45.hh>

Inheritance diagram for G4CashKarpRKF45:

Public Member Functions
	G4CashKarpRKF45 (G4EquationOfMotion *EqRhs, G4int numberOfVariables=6, G4bool primary=true)
	~G4CashKarpRKF45 ()
void	Stepper (const G4double y[], const G4double dydx[], G4double h, G4double yout[], G4double yerr[])
G4double	DistChord () const
G4int	IntegratorOrder () const
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
virtual void	Stepper (const G4double y[], const G4double dydx[], G4double h, G4double yout[], G4double yerr[])=0
virtual G4double	DistChord () const =0
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
G4int	IntegrationOrder ()
G4EquationOfMotion *	GetEquationOfMotion ()
const G4EquationOfMotion *	GetEquationOfMotion () const
void	SetEquationOfMotion (G4EquationOfMotion *newEquation)
unsigned long	GetfNoRHSCalls ()
void	ResetfNORHSCalls ()
G4bool	IsFSAL () const

Additional Inherited Members
Protected Member Functions inherited from G4MagIntegratorStepper
void	SetIntegrationOrder (G4int order)
void	SetFSAL (G4bool flag=true)

Detailed Description

Definition at line 44 of file G4CashKarpRKF45.hh.

Constructor & Destructor Documentation

G4CashKarpRKF45()

G4CashKarpRKF45::G4CashKarpRKF45	(	G4EquationOfMotion *	EqRhs,
		G4int	numberOfVariables = 6,
		G4bool	primary = true
	)

Definition at line 47 of file G4CashKarpRKF45.cc.

  : G4MagIntegratorStepper(EqRhs, noIntegrationVariables)
{
  const G4int numberOfVariables =
      std::max( noIntegrationVariables,
               ( ( (noIntegrationVariables-1)/4 + 1 ) * 4 ) );
  // For better alignment with cache-line
  
  ak2 = new G4double[numberOfVariables] ;
  ak3 = new G4double[numberOfVariables] ;
  ak4 = new G4double[numberOfVariables] ;
  ak5 = new G4double[numberOfVariables] ;
  ak6 = new G4double[numberOfVariables] ;
  // ak7 = 0;
 
  // Must ensure space extra 'state' variables exists - i.e. yIn[7]
  const G4int numStateMax  = std::max(GetNumberOfStateVariables(), 8);  
  const G4int numStateVars = std::max(noIntegrationVariables,
                                      numStateMax );
                                   // GetNumberOfStateVariables() ); 
                                      
  yTemp = new G4double[numStateVars] ;
  yIn = new G4double[numStateVars] ;
 
  fLastInitialVector = new G4double[numStateVars] ;
  fLastFinalVector = new G4double[numStateVars] ;
  fLastDyDx = new G4double[numberOfVariables];
 
  fMidVector = new G4double[numStateVars];
  fMidError =  new G4double[numStateVars];
  if( primary )
  { 
    fAuxStepper = new G4CashKarpRKF45(EqRhs, numberOfVariables, !primary);
  }
}

~G4CashKarpRKF45()

G4CashKarpRKF45::~G4CashKarpRKF45

(

)

Definition at line 89 of file G4CashKarpRKF45.cc.

{
  delete [] ak2;
  delete [] ak3;
  delete [] ak4;
  delete [] ak5;
  delete [] ak6;
  // delete [] ak7;
  delete [] yTemp;
  delete [] yIn;
 
  delete [] fLastInitialVector;
  delete [] fLastFinalVector;
  delete [] fLastDyDx;
  delete [] fMidVector;
  delete [] fMidError; 
 
  delete fAuxStepper;
}

Member Function Documentation

DistChord()

G4double G4CashKarpRKF45::DistChord ( ) const

virtual

Implements G4MagIntegratorStepper.

Definition at line 238 of file G4CashKarpRKF45.cc.

{
  G4double distLine, distChord; 
  G4ThreeVector initialPoint, finalPoint, midPoint;
 
  // Store last initial and final points
  // (they will be overwritten in self-Stepper call!)
  //
  initialPoint = G4ThreeVector( fLastInitialVector[0], 
                                fLastInitialVector[1], fLastInitialVector[2]); 
  finalPoint   = G4ThreeVector( fLastFinalVector[0],  
                                fLastFinalVector[1],  fLastFinalVector[2]); 
 
  // Do half a step using StepNoErr
  //
  fAuxStepper->Stepper( fLastInitialVector, fLastDyDx,
                        0.5 * fLastStepLength, fMidVector, fMidError );
 
  midPoint = G4ThreeVector( fMidVector[0], fMidVector[1], fMidVector[2]);       
 
  // Use stored values of Initial and Endpoint + new Midpoint to evaluate
  // distance of Chord
  //
  if (initialPoint != finalPoint) 
  {
     distLine  = G4LineSection::Distline( midPoint, initialPoint, finalPoint );
     distChord = distLine;
  }
  else
  {
     distChord = (midPoint-initialPoint).mag();
  }
  return distChord;
}

IntegratorOrder()

G4int G4CashKarpRKF45::IntegratorOrder ( ) const

inlinevirtual

Implements G4MagIntegratorStepper.

Definition at line 63 of file G4CashKarpRKF45.hh.

{ return 4; }

Stepper()

void G4CashKarpRKF45::Stepper ( const G4double  y[], const G4double  dydx[], G4double  h, G4double  yout[], G4double  yerr[]  )

virtual

Implements G4MagIntegratorStepper.

Definition at line 120 of file G4CashKarpRKF45.cc.

{
  // const G4int nvar = 6 ;
  // const G4double a2 = 0.2 , a3 = 0.3 , a4 = 0.6 , a5 = 1.0 , a6 = 0.875;
  G4int i;
 
  const G4double  b21 = 0.2 ,
                  b31 = 3.0/40.0 , b32 = 9.0/40.0 ,
                  b41 = 0.3 , b42 = -0.9 , b43 = 1.2 ,
 
                  b51 = -11.0/54.0 , b52 = 2.5 , b53 = -70.0/27.0 ,
                  b54 = 35.0/27.0 ,
 
                  b61 = 1631.0/55296.0 , b62 =   175.0/512.0 ,
                  b63 =  575.0/13824.0 , b64 = 44275.0/110592.0 ,
                  b65 =  253.0/4096.0 ,
 
                  c1 = 37.0/378.0 , c3 = 250.0/621.0 , c4 = 125.0/594.0 ,
                  c6 = 512.0/1771.0 , dc5 = -277.0/14336.0 ;
 
  const G4double dc1 = c1 - 2825.0/27648.0 ,  dc3 = c3 - 18575.0/48384.0 ,
                 dc4 = c4 - 13525.0/55296.0 , dc6 = c6 - 0.25 ;
 
  // 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.] 
  yOut[7] = yTemp[7] = yIn[7] = yInput[7]; 
 
  const G4int numberOfVariables= this->GetNumberOfVariables(); 
    // The number of variables to be integrated over
 
  //  Saving yInput because yInput and yOut can be aliases for same array
 
  for(i=0; i<numberOfVariables; ++i) 
  {
    yIn[i]=yInput[i];
  }
  // RightHandSide(yIn, dydx) ;            // 1st Step
 
  for(i=0; i<numberOfVariables; ++i) 
  {
    yTemp[i] = yIn[i] + b21*Step*dydx[i] ;
  }
  RightHandSide(yTemp, ak2) ;              // 2nd Step
 
  for(i=0; i<numberOfVariables; ++i)
  {
    yTemp[i] = yIn[i] + Step*(b31*dydx[i] + b32*ak2[i]) ;
  }
  RightHandSide(yTemp, ak3) ;              // 3rd Step
 
  for(i=0; i<numberOfVariables; ++i)
  {
    yTemp[i] = yIn[i] + Step*(b41*dydx[i] + b42*ak2[i] + b43*ak3[i]) ;
  }
  RightHandSide(yTemp, ak4) ;              // 4th Step
 
  for(i=0; i<numberOfVariables; ++i)
  {
    yTemp[i] = yIn[i] + Step*(b51*dydx[i]
                      + b52*ak2[i] + b53*ak3[i] + b54*ak4[i]) ;
  }
  RightHandSide(yTemp, ak5) ;              // 5th Step
 
  for(i=0; i<numberOfVariables; ++i)
  {
    yTemp[i] = yIn[i] + Step*(b61*dydx[i]
                      + b62*ak2[i] + b63*ak3[i] + b64*ak4[i] + b65*ak5[i]) ;
  }
  RightHandSide(yTemp, ak6) ;              // 6th Step
 
  for(i=0; i<numberOfVariables; ++i)
  {
    // Accumulate increments with proper weights
    //
    yOut[i] = yIn[i] + Step*(c1*dydx[i] + c3*ak3[i] + c4*ak4[i] + c6*ak6[i]) ;
 
    // Estimate error as difference between 4th and 5th order methods
    //
    yErr[i] = Step*(dc1*dydx[i]
            + dc3*ak3[i] + dc4*ak4[i] + dc5*ak5[i] + dc6*ak6[i]) ;
 
    // Store Input and Final values, for possible use in calculating chord
    //
    fLastInitialVector[i] = yIn[i] ;
    fLastFinalVector[i]   = yOut[i];
    fLastDyDx[i]          = dydx[i];
  }
  // NormaliseTangentVector( yOut ); // Not wanted
 
  fLastStepLength = Step;
 
  return;
} 

Referenced by DistChord().

---

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

• G4CashKarpRKF45.hh
• G4CashKarpRKF45.cc