G4ChordFinder Class Reference

#include <G4ChordFinder.hh>

Inheritance diagram for G4ChordFinder:

Public Member Functions
	G4ChordFinder (G4MagInt_Driver *pIntegrationDriver)
	G4ChordFinder (G4MagneticField *itsMagField, G4double stepMinimum=1.0e-2, G4MagIntegratorStepper *pItsStepper=0)
virtual	~G4ChordFinder ()
G4double	AdvanceChordLimited (G4FieldTrack &yCurrent, G4double stepInitial, G4double epsStep_Relative, const G4ThreeVector latestSafetyOrigin, G4double lasestSafetyRadius)
G4FieldTrack	ApproxCurvePointS (const G4FieldTrack &curveAPointVelocity, const G4FieldTrack &curveBPointVelocity, const G4FieldTrack &ApproxCurveV, const G4ThreeVector &currentEPoint, const G4ThreeVector &currentFPoint, const G4ThreeVector &PointG, G4bool first, G4double epsStep)
G4FieldTrack	ApproxCurvePointV (const G4FieldTrack &curveAPointVelocity, const G4FieldTrack &curveBPointVelocity, const G4ThreeVector &currentEPoint, G4double epsStep)
G4double	InvParabolic (const G4double xa, const G4double ya, const G4double xb, const G4double yb, const G4double xc, const G4double yc)
G4double	GetDeltaChord () const
void	SetDeltaChord (G4double newval)
void	SetChargeMomentumMass (G4double pCharge, G4double pMomentum, G4double pMass)
void	SetIntegrationDriver (G4MagInt_Driver *IntegrationDriver)
G4MagInt_Driver *	GetIntegrationDriver ()
void	ResetStepEstimate ()
G4int	GetNoCalls ()
G4int	GetNoTrials ()
G4int	GetNoMaxTrials ()
virtual void	PrintStatistics ()
G4int	SetVerbose (G4int newvalue=1)
void	SetFractions_Last_Next (G4double fractLast=0.90, G4double fractNext=0.95)
void	SetFirstFraction (G4double fractFirst)
void	TestChordPrint (G4int noTrials, G4int lastStepTrial, G4double dChordStep, G4double nextStepTrial)
G4double	GetFirstFraction ()
G4double	GetFractionLast ()
G4double	GetFractionNextEstimate ()
G4double	GetMultipleRadius ()
Protected Member Functions
void	AccumulateStatistics (G4int noTrials)
G4bool	AcceptableMissDist (G4double dChordStep) const
G4double	NewStep (G4double stepTrialOld, G4double dChordStep, G4double &stepEstimate_Unconstrained)
virtual G4double	FindNextChord (const G4FieldTrack &yStart, G4double stepMax, G4FieldTrack &yEnd, G4double &dyErr, G4double epsStep, G4double *pNextStepForAccuracy, const G4ThreeVector latestSafetyOrigin, G4double latestSafetyRadius)
void	PrintDchordTrial (G4int noTrials, G4double stepTrial, G4double oldStepTrial, G4double dChordStep)
G4double	GetLastStepEstimateUnc ()
void	SetLastStepEstimateUnc (G4double stepEst)

---

Detailed Description

Definition at line 50 of file G4ChordFinder.hh.

---

Constructor & Destructor Documentation

G4ChordFinder::G4ChordFinder

(

G4MagInt_Driver *

pIntegrationDriver

)

Definition at line 44 of file G4ChordFinder.cc.

References DBL_MAX, and SetFractions_Last_Next().

  : fDefaultDeltaChord( 0.25 * mm ),      // Parameters
    fDeltaChord( fDefaultDeltaChord ),    //   Internal parameters
    fFirstFraction(0.999), fFractionLast(1.00),  fFractionNextEstimate(0.98), 
    fMultipleRadius(15.0), 
    fStatsVerbose(0),
    fDriversStepper(0),                    // Dependent objects 
    fAllocatedStepper(false),
    fEquation(0),      
    fTotalNoTrials_FNC(0), fNoCalls_FNC(0), fmaxTrials_FNC(0)
{
  // Simple constructor -- it does not create equation
  fIntgrDriver= pIntegrationDriver;
  fAllocatedStepper= false;

  fLastStepEstimate_Unconstrained = DBL_MAX;          // Should move q, p to

  SetFractions_Last_Next( fFractionLast, fFractionNextEstimate);  
    // check the values and set the other parameters
}

G4ChordFinder::G4ChordFinder	(	G4MagneticField *	itsMagField,
		G4double	stepMinimum = 1.0e-2,
		G4MagIntegratorStepper *	pItsStepper = 0
	)

Definition at line 68 of file G4ChordFinder.cc.

References DBL_MAX, G4MagIntegratorStepper::GetNumberOfVariables(), and SetFractions_Last_Next().

  : fDefaultDeltaChord( 0.25 * mm ),     // Constants 
    fDeltaChord( fDefaultDeltaChord ),   // Parameters
    fFirstFraction(0.999), fFractionLast(1.00),  fFractionNextEstimate(0.98), 
    fMultipleRadius(15.0), 
    fStatsVerbose(0),
    fDriversStepper(0),                  //  Dependent objects
    fAllocatedStepper(false),
    fEquation(0), 
    fTotalNoTrials_FNC(0), fNoCalls_FNC(0), fmaxTrials_FNC(0)  // State - stats
{
  //  Construct the Chord Finder
  //  by creating in inverse order the  Driver, the Stepper and EqRhs ...

  G4Mag_EqRhs *pEquation = new G4Mag_UsualEqRhs(theMagField);
  fEquation = pEquation;                            
  fLastStepEstimate_Unconstrained = DBL_MAX;          // Should move q, p to
                                                     //    G4FieldTrack ??

  SetFractions_Last_Next( fFractionLast, fFractionNextEstimate);  
    // check the values and set the other parameters

  // --->>  Charge    Q = 0 
  // --->>  Momentum  P = 1       NOMINAL VALUES !!!!!!!!!!!!!!!!!!

  if( pItsStepper == 0 )
  { 
     pItsStepper = fDriversStepper = new G4ClassicalRK4(pEquation);
     fAllocatedStepper= true;
  }
  else
  {
     fAllocatedStepper= false; 
  }
  fIntgrDriver = new G4MagInt_Driver(stepMinimum, pItsStepper, 
                                     pItsStepper->GetNumberOfVariables() );
}

G4ChordFinder::~G4ChordFinder

(

)

[virtual]

Definition at line 111 of file G4ChordFinder.cc.

References PrintStatistics().

{
  delete   fEquation; // fIntgrDriver->pIntStepper->theEquation_Rhs;
  if( fAllocatedStepper)
  { 
     delete fDriversStepper; 
  }
  delete   fIntgrDriver; 

  if( fStatsVerbose ) { PrintStatistics(); }
}

---

Member Function Documentation

G4bool G4ChordFinder::AcceptableMissDist

(

G4double

dChordStep

)

const [inline, protected]

Definition at line 46 of file G4ChordFinder.icc.

Referenced by G4ChordFinderSaf::FindNextChord(), and FindNextChord().

{ 
  return (dChordStep <= fDeltaChord) ;
}

void G4ChordFinder::AccumulateStatistics

(

G4int

noTrials

)

[inline, protected]

Definition at line 110 of file G4ChordFinder.icc.

Referenced by G4ChordFinderSaf::FindNextChord(), and FindNextChord().

{
  // Statistics 
  fTotalNoTrials_FNC += noTrials; 
  fNoCalls_FNC++; 
  // if( noTrials >= fmaxTrials_FNC ){
    if (noTrials > fmaxTrials_FNC ) { 
      fmaxTrials_FNC=noTrials; 
      // fnoTimesMaxTrFNC=0; 
    } else { 
      // fnoTimesMaxTrFNC++; 
    } 
  // } 
}

G4double G4ChordFinder::AdvanceChordLimited	(	G4FieldTrack &	yCurrent,
		G4double	stepInitial,
		G4double	epsStep_Relative,
		const G4ThreeVector	latestSafetyOrigin,
		G4double	lasestSafetyRadius
	)

Definition at line 172 of file G4ChordFinder.cc.

References G4MagInt_Driver::AccurateAdvance(), FindNextChord(), and G4FieldTrack::GetCurveLength().

Referenced by G4PropagatorInField::ComputeStep().

{
  G4double stepPossible;
  G4double dyErr;
  G4FieldTrack yEnd( yCurrent);
  G4double  startCurveLen= yCurrent.GetCurveLength();
  G4double nextStep;
  //            *************
  stepPossible= FindNextChord(yCurrent, stepMax, yEnd, dyErr, epsStep,
                              &nextStep, latestSafetyOrigin, latestSafetyRadius
                             );
  //            *************

  G4bool good_advance;

  if ( dyErr < epsStep * stepPossible )
  {
     // Accept this accuracy.

     yCurrent = yEnd;
     good_advance = true; 
  }
  else
  {  
     // Advance more accurately to "end of chord"
     //                           ***************
     good_advance = fIntgrDriver->AccurateAdvance(yCurrent, stepPossible,
                                                  epsStep, nextStep);
     if ( ! good_advance )
     { 
       // In this case the driver could not do the full distance
       stepPossible= yCurrent.GetCurveLength()-startCurveLen;
     }
  }
  return stepPossible;
}

G4FieldTrack G4ChordFinder::ApproxCurvePointS	(	const G4FieldTrack &	curveAPointVelocity,
		const G4FieldTrack &	curveBPointVelocity,
		const G4FieldTrack &	ApproxCurveV,
		const G4ThreeVector &	currentEPoint,
		const G4ThreeVector &	currentFPoint,
		const G4ThreeVector &	PointG,
		G4bool	first,
		G4double	epsStep
	)

Definition at line 413 of file G4ChordFinder.cc.

References G4MagInt_Driver::AccurateAdvance(), ApproxCurvePointV(), G4cout, G4endl, G4FieldTrack::GetCurveLength(), G4FieldTrack::GetPosition(), and InvParabolic().

Referenced by G4BrentLocator::EstimateIntersectionPoint().

{
  // ApproxCurvePointS is 2nd implementation of ApproxCurvePoint.
  // Use Brent Algorithm (or InvParabolic) when possible.
  // Given a starting curve point A (CurveA_PointVelocity), curve point B
  // (CurveB_PointVelocity), a point E which is (generally) not on the curve
  // and  a point F which is on the curve (first approximation), find new
  // point S on the curve closer to point E. 
  // While advancing towards S utilise 'eps_step' as a measure of the
  // relative accuracy of each Step.

  G4FieldTrack EndPoint(CurveA_PointVelocity);
  if(!first){EndPoint= ApproxCurveV;}

  G4ThreeVector Point_A,Point_B;
  Point_A=CurveA_PointVelocity.GetPosition();
  Point_B=CurveB_PointVelocity.GetPosition();

  G4double xa,xb,xc,ya,yb,yc;
 
  // InverseParabolic. AF Intersects (First Part of Curve) 

  if(first)
  {
    xa=0.;
    ya=(PointG-Point_A).mag();
    xb=(Point_A-CurrentF_Point).mag();
    yb=-(PointG-CurrentF_Point).mag();
    xc=(Point_A-Point_B).mag();
    yc=-(CurrentE_Point-Point_B).mag();
  }    
  else
  {
    xa=0.;
    ya=(Point_A-CurrentE_Point).mag();
    xb=(Point_A-CurrentF_Point).mag();
    yb=(PointG-CurrentF_Point).mag();
    xc=(Point_A-Point_B).mag();
    yc=-(Point_B-PointG).mag();
    if(xb==0.)
    {
      EndPoint=
      ApproxCurvePointV(CurveA_PointVelocity, CurveB_PointVelocity,
                        CurrentE_Point, eps_step);
      return EndPoint;
    }
  }

  const G4double tolerance= 1.e-12;
  if(std::abs(ya)<=tolerance||std::abs(yc)<=tolerance)
  {
    ; // What to do for the moment: return the same point as at start
      // then PropagatorInField will take care
  }
  else
  {
    G4double test_step = InvParabolic(xa,ya,xb,yb,xc,yc);
    G4double curve;
    if(first)
    {
      curve=std::abs(EndPoint.GetCurveLength()
                    -ApproxCurveV.GetCurveLength());
    }
    else
    {
      test_step=(test_step-xb);
      curve=std::abs(EndPoint.GetCurveLength()
                    -CurveB_PointVelocity.GetCurveLength());
      xb=(CurrentF_Point-Point_B).mag();
    }
      
    if(test_step<=0)    { test_step=0.1*xb; }
    if(test_step>=xb)   { test_step=0.5*xb; }
    if(test_step>=curve){ test_step=0.5*curve; } 

    if(curve*(1.+eps_step)<xb) // Similar to ReEstimate Step from
    {                          // G4VIntersectionLocator
      test_step=0.5*curve;
    }

    fIntgrDriver->AccurateAdvance(EndPoint,test_step, eps_step);
      
#ifdef G4DEBUG_FIELD
    // Printing Brent and Linear Approximation
    //
    G4cout << "G4ChordFinder::ApproxCurvePointS() - test-step ShF = "
           << test_step << "  EndPoint = " << EndPoint << G4endl;

    //  Test Track
    //
    G4FieldTrack TestTrack( CurveA_PointVelocity);
    TestTrack = ApproxCurvePointV( CurveA_PointVelocity, 
                                   CurveB_PointVelocity, 
                                   CurrentE_Point, eps_step );
    G4cout.precision(14);
    G4cout << "G4ChordFinder::BrentApprox = " << EndPoint  << G4endl;
    G4cout << "G4ChordFinder::LinearApprox= " << TestTrack << G4endl; 
#endif
  }
  return EndPoint;
}

G4FieldTrack G4ChordFinder::ApproxCurvePointV	(	const G4FieldTrack &	curveAPointVelocity,
		const G4FieldTrack &	curveBPointVelocity,
		const G4ThreeVector &	currentEPoint,
		G4double	epsStep
	)

Definition at line 525 of file G4ChordFinder.cc.

References G4MagInt_Driver::AccurateAdvance(), FatalException, G4cerr, G4cout, G4endl, G4Exception(), G4FieldTrack::GetCurveLength(), and G4FieldTrack::GetPosition().

Referenced by ApproxCurvePointS(), G4SimpleLocator::EstimateIntersectionPoint(), G4MultiLevelLocator::EstimateIntersectionPoint(), and G4BrentLocator::EstimateIntersectionPoint().

{
  // If r=|AE|/|AB|, and s=true path lenght (AB)
  // return the point that is r*s along the curve!
 
  G4FieldTrack   Current_PointVelocity = CurveA_PointVelocity; 

  G4ThreeVector  CurveA_Point= CurveA_PointVelocity.GetPosition();
  G4ThreeVector  CurveB_Point= CurveB_PointVelocity.GetPosition();

  G4ThreeVector  ChordAB_Vector= CurveB_Point   - CurveA_Point;
  G4ThreeVector  ChordAE_Vector= CurrentE_Point - CurveA_Point;

  G4double       ABdist= ChordAB_Vector.mag();
  G4double  curve_length;  //  A curve length  of AB
  G4double  AE_fraction; 
  
  curve_length= CurveB_PointVelocity.GetCurveLength()
              - CurveA_PointVelocity.GetCurveLength();  
 
  G4double  integrationInaccuracyLimit= std::max( perMillion, 0.5*eps_step ); 
  if( curve_length < ABdist * (1. - integrationInaccuracyLimit) )
  { 
#ifdef G4DEBUG_FIELD
    G4cerr << " Warning in G4ChordFinder::ApproxCurvePoint: "
           << G4endl
           << " The two points are further apart than the curve length "
           << G4endl
           << " Dist = "         << ABdist
           << " curve length = " << curve_length 
           << " relativeDiff = " << (curve_length-ABdist)/ABdist 
           << G4endl;
    if( curve_length < ABdist * (1. - 10*eps_step) )
    {
      std::ostringstream message;
      message << "Unphysical curve length." << G4endl
              << "The size of the above difference exceeds allowed limits."
              << G4endl
              << "Aborting.";
      G4Exception("G4ChordFinder::ApproxCurvePointV()", "GeomField0003",
                  FatalException, message);
    }
#endif
    // Take default corrective action: adjust the maximum curve length. 
    // NOTE: this case only happens for relatively straight paths.
    // curve_length = ABdist; 
  }

  G4double  new_st_length; 

  if ( ABdist > 0.0 )
  {
     AE_fraction = ChordAE_Vector.mag() / ABdist;
  }
  else
  {
     AE_fraction = 0.5;                         // Guess .. ?; 
#ifdef G4DEBUG_FIELD
     G4cout << "Warning in G4ChordFinder::ApproxCurvePointV():"
            << " A and B are the same point!" << G4endl
            << " Chord AB length = " << ChordAE_Vector.mag() << G4endl
            << G4endl;
#endif
  }
  
  if( (AE_fraction> 1.0 + perMillion) || (AE_fraction< 0.) )
  {
#ifdef G4DEBUG_FIELD
    G4cerr << " G4ChordFinder::ApproxCurvePointV() - Warning:"
           << " Anomalous condition:AE > AB or AE/AB <= 0 " << G4endl
           << "   AE_fraction = " <<  AE_fraction << G4endl
           << "   Chord AE length = " << ChordAE_Vector.mag() << G4endl
           << "   Chord AB length = " << ABdist << G4endl << G4endl;
    G4cerr << " OK if this condition occurs after a recalculation of 'B'"
           << G4endl << " Otherwise it is an error. " << G4endl ; 
#endif
     // This course can now result if B has been re-evaluated, 
     // without E being recomputed (1 July 99).
     // In this case this is not a "real error" - but it is undesired
     // and we cope with it by a default corrective action ...
     //
     AE_fraction = 0.5;                         // Default value
  }

  new_st_length= AE_fraction * curve_length; 

  if ( AE_fraction > 0.0 )
  { 
     fIntgrDriver->AccurateAdvance(Current_PointVelocity, 
                                   new_st_length, eps_step );
     //
     // In this case it does not matter if it cannot advance the full distance
  }

  // If there was a memory of the step_length actually required at the start 
  // of the integration Step, this could be re-used ...

  G4cout.precision(14);

  return Current_PointVelocity;
}

G4double G4ChordFinder::FindNextChord	(	const G4FieldTrack &	yStart,
		G4double	stepMax,
		G4FieldTrack &	yEnd,
		G4double &	dyErr,
		G4double	epsStep,
		G4double *	pNextStepForAccuracy,
		const G4ThreeVector	latestSafetyOrigin,
		G4double	latestSafetyRadius
	)			[protected, virtual]

Reimplemented in G4ChordFinderSaf.

Definition at line 217 of file G4ChordFinder.cc.

References AcceptableMissDist(), AccumulateStatistics(), G4MagInt_Driver::ComputeNewStepSize(), G4cout, G4endl, G4FieldTrack::ncompSVEC, NewStep(), and G4MagInt_Driver::QuickAdvance().

Referenced by AdvanceChordLimited().

{
  // Returns Length of Step taken

  G4FieldTrack yCurrent=  yStart;  
  G4double    stepTrial, stepForAccuracy;
  G4double    dydx[G4FieldTrack::ncompSVEC]; 

  //  1.)  Try to "leap" to end of interval
  //  2.)  Evaluate if resulting chord gives d_chord that is good enough.
  // 2a.)  If d_chord is not good enough, find one that is.
  
  G4bool    validEndPoint= false;
  G4double  dChordStep, lastStepLength; //  stepOfLastGoodChord;

  fIntgrDriver-> GetDerivatives( yCurrent, dydx );

  G4int     noTrials=0;
  const G4double safetyFactor= fFirstFraction; //  0.975 or 0.99 ? was 0.999

  stepTrial = std::min( stepMax, safetyFactor*fLastStepEstimate_Unconstrained );

  G4double newStepEst_Uncons= 0.0; 
  do
  { 
     G4double stepForChord;  
     yCurrent = yStart;    // Always start from initial point
    
     //            ************
     fIntgrDriver->QuickAdvance( yCurrent, dydx, stepTrial, 
                                 dChordStep, dyErrPos);
     //            ************
     
     //  We check whether the criterion is met here.
     validEndPoint = AcceptableMissDist(dChordStep);

     lastStepLength = stepTrial; 

     // This method estimates to step size for a good chord.
     stepForChord = NewStep(stepTrial, dChordStep, newStepEst_Uncons );

     if( ! validEndPoint )
     {
        if( stepTrial<=0.0 )
        {
          stepTrial = stepForChord;
        }
        else if (stepForChord <= stepTrial)
        {
          // Reduce by a fraction, possibly up to 20% 
          stepTrial = std::min( stepForChord, fFractionLast * stepTrial);
        }
        else
        {
          stepTrial *= 0.1;
        }
     }
     noTrials++; 
  }
  while( ! validEndPoint );   // End of do-while  RKD 

  if( newStepEst_Uncons > 0.0  )
  {
     fLastStepEstimate_Unconstrained= newStepEst_Uncons;
  }

  AccumulateStatistics( noTrials );

  if( pStepForAccuracy )
  { 
     // Calculate the step size required for accuracy, if it is needed
     //
     G4double dyErr_relative = dyErrPos/(epsStep*lastStepLength);
     if( dyErr_relative > 1.0 )
     {
        stepForAccuracy = fIntgrDriver->ComputeNewStepSize( dyErr_relative,
                                                            lastStepLength );
     }
     else
     {
        stepForAccuracy = 0.0;   // Convention to show step was ok 
     }
     *pStepForAccuracy = stepForAccuracy;
  }

#ifdef  TEST_CHORD_PRINT
  static int dbg=0;
  if( dbg )
  {
    G4cout << "ChordF/FindNextChord:  NoTrials= " << noTrials 
           << " StepForGoodChord=" << std::setw(10) << stepTrial << G4endl;
  }
#endif
  yEnd=  yCurrent;  
  return stepTrial; 
}

G4double G4ChordFinder::GetDeltaChord

(

)

const [inline]

Definition at line 60 of file G4ChordFinder.icc.

{
  return fDeltaChord;
}

G4double G4ChordFinder::GetFirstFraction

(

)

[inline]

Definition at line 93 of file G4ChordFinder.icc.

Referenced by G4ChordFinderSaf::FindNextChord().

{ return fFirstFraction; } 

G4double G4ChordFinder::GetFractionLast

(

)

[inline]

Definition at line 94 of file G4ChordFinder.icc.

Referenced by G4ChordFinderSaf::FindNextChord().

{ return fFractionLast; } 

G4double G4ChordFinder::GetFractionNextEstimate

(

)

[inline]

Definition at line 95 of file G4ChordFinder.icc.

{ return fFractionNextEstimate; } 

G4MagInt_Driver * G4ChordFinder::GetIntegrationDriver

(

)

[inline]

Definition at line 40 of file G4ChordFinder.icc.

Referenced by G4MultiLevelLocator::EstimateIntersectionPoint(), G4BrentLocator::EstimateIntersectionPoint(), G4ChordFinderSaf::FindNextChord(), G4ErrorPropagatorManager::InitFieldForBackwards(), G4VIntersectionLocator::ReEstimateEndpoint(), and G4PropagatorInField::SetVerboseLevel().

{
  return fIntgrDriver;
}

G4double G4ChordFinder::GetLastStepEstimateUnc

(

)

[inline, protected]

Definition at line 73 of file G4ChordFinder.icc.

Referenced by G4ChordFinderSaf::FindNextChord().

{
  return fLastStepEstimate_Unconstrained;   
} 

G4double G4ChordFinder::GetMultipleRadius

(

)

[inline]

Definition at line 97 of file G4ChordFinder.icc.

{ return fMultipleRadius; } 

G4int G4ChordFinder::GetNoCalls

(

)

[inline]

Definition at line 89 of file G4ChordFinder.icc.

{ return fNoCalls_FNC; }

G4int G4ChordFinder::GetNoMaxTrials

(

)

[inline]

Definition at line 91 of file G4ChordFinder.icc.

{ return fmaxTrials_FNC; } 

G4int G4ChordFinder::GetNoTrials

(

)

[inline]

Definition at line 90 of file G4ChordFinder.icc.

{ return fTotalNoTrials_FNC; }

G4double G4ChordFinder::InvParabolic	(	const G4double	xa,
		const G4double	ya,
		const G4double	xb,
		const G4double	yb,
		const G4double	xc,
		const G4double	yc
	)			[inline]

Definition at line 128 of file G4ChordFinder.icc.

References DBL_MAX, and DBL_MIN.

Referenced by ApproxCurvePointS().

{       const G4double R = yb/yc,
                       S = yb/ya,
                       T = ya/yc;
        const G4double Q = (T-1)*(R-1)*(S-1);
        if (std::fabs(Q) <DBL_MIN ) return  DBL_MAX;
        
        const G4double P = S*(T*(R-T)*(xc-xb) - (1-R)*(xb-xa));
        return xb + P/Q;
}

G4double G4ChordFinder::NewStep	(	G4double	stepTrialOld,
		G4double	dChordStep,
		G4double &	stepEstimate_Unconstrained
	)			[protected]

Definition at line 325 of file G4ChordFinder.cc.

Referenced by G4ChordFinderSaf::FindNextChord(), and FindNextChord().

{
  // Is called to estimate the next step size, even for successful steps,
  // in order to predict an accurate 'chord-sensitive' first step
  // which is likely to assist in more performant 'stepping'.

  G4double stepTrial;

#if 1

  if (dChordStep > 0.0)
  {
    stepEstimate_Unconstrained =
                 stepTrialOld*std::sqrt( fDeltaChord / dChordStep );
    stepTrial =  fFractionNextEstimate * stepEstimate_Unconstrained;
  }
  else
  {
    // Should not update the Unconstrained Step estimate: incorrect!
    stepTrial =  stepTrialOld * 2.; 
  }

  if( stepTrial <= 0.001 * stepTrialOld)
  {
     if ( dChordStep > 1000.0 * fDeltaChord )
     {
        stepTrial= stepTrialOld * 0.03;   
     }
     else
     {
        if ( dChordStep > 100. * fDeltaChord )
        {
          stepTrial= stepTrialOld * 0.1;   
        }
        else   // Try halving the length until dChordStep OK
        {
          stepTrial= stepTrialOld * 0.5;   
        }
     }
  }
  else if (stepTrial > 1000.0 * stepTrialOld)
  {
     stepTrial= 1000.0 * stepTrialOld;
  }

  if( stepTrial == 0.0 )
  {
     stepTrial= 0.000001;
  }

#else

  if ( dChordStep > 1000. * fDeltaChord )
  {
        stepTrial= stepTrialOld * 0.03;   
  }
  else
  {
     if ( dChordStep > 100. * fDeltaChord )
     {
        stepTrial= stepTrialOld * 0.1;   
     }
     else  // Keep halving the length until dChordStep OK
     {
        stepTrial= stepTrialOld * 0.5;   
     }
  }

#endif 

  // A more sophisticated chord-finder could figure out a better
  // stepTrial, from dChordStep and the required d_geometry
  //   e.g.
  //      Calculate R, r_helix (eg at orig point)
  //      if( stepTrial < 2 pi  R )
  //          stepTrial = R arc_cos( 1 - fDeltaChord / r_helix )
  //      else    
  //          ??

  return stepTrial;
}

void G4ChordFinder::PrintDchordTrial	(	G4int	noTrials,
		G4double	stepTrial,
		G4double	oldStepTrial,
		G4double	dChordStep
	)			[protected]

void G4ChordFinder::PrintStatistics

(

)

[virtual]

Reimplemented in G4ChordFinderSaf.

Definition at line 634 of file G4ChordFinder.cc.

References G4cout, and G4endl.

Referenced by G4ChordFinderSaf::PrintStatistics(), and ~G4ChordFinder().

{
  // Print Statistics

  G4cout << "G4ChordFinder statistics report: " << G4endl;
  G4cout 
    << "  No trials: " << fTotalNoTrials_FNC
    << "  No Calls: "  << fNoCalls_FNC
    << "  Max-trial: " <<  fmaxTrials_FNC
    << G4endl; 
  G4cout 
    << "  Parameters: " 
    << "  fFirstFraction "  << fFirstFraction
    << "  fFractionLast "   << fFractionLast
    << "  fFractionNextEstimate " << fFractionNextEstimate
    << G4endl; 
}

void G4ChordFinder::ResetStepEstimate

(

)

[inline]

Definition at line 83 of file G4ChordFinder.icc.

References DBL_MAX.

Referenced by G4FieldManagerStore::ClearAllChordFindersState(), and G4CoupledTransportation::StartTracking().

{
  fLastStepEstimate_Unconstrained = DBL_MAX;    
}

void G4ChordFinder::SetChargeMomentumMass	(	G4double	pCharge,
		G4double	pMomentum,
		G4double	pMass
	)			[inline]

Definition at line 52 of file G4ChordFinder.icc.

Referenced by G4PropagatorInField::ComputeStep().

{
  fIntgrDriver-> SetChargeMomentumMass(pCharge, pMomentum, pMass);
}

void G4ChordFinder::SetDeltaChord

(

G4double

newval

)

[inline]

Definition at line 66 of file G4ChordFinder.icc.

{
  fDeltaChord=newval;
}

void G4ChordFinder::SetFirstFraction

(

G4double

fractFirst

)

[inline]

Definition at line 100 of file G4ChordFinder.icc.

{ fFirstFraction=val; }

void G4ChordFinder::SetFractions_Last_Next	(	G4double	fractLast = 0.90,
		G4double	fractNext = 0.95
	)

Definition at line 127 of file G4ChordFinder.cc.

References G4cerr, G4cout, and G4endl.

Referenced by G4ChordFinder().

{ 
  // Use -1.0 as request for Default.
  if( fractLast == -1.0 )   fractLast = 1.0;   // 0.9;
  if( fractNext == -1.0 )   fractNext = 0.98;  // 0.9; 

  // fFirstFraction  = 0.999; // Orig 0.999 A safe value, range: ~ 0.95 - 0.999
  // fMultipleRadius = 15.0;  // For later use, range: ~  2 - 20 

  if( fStatsVerbose )
  { 
    G4cout << " ChordFnd> Trying to set fractions: "
           << " first " << fFirstFraction
           << " last " <<  fractLast
           << " next " <<  fractNext
           << " and multiple " << fMultipleRadius
           << G4endl;
  } 

  if( (fractLast > 0.0) && (fractLast <=1.0) ) 
  {
    fFractionLast= fractLast;
  }
  else
  {
    G4cerr << "G4ChordFinder::SetFractions_Last_Next: Invalid "
           << " fraction Last = " << fractLast
           << " must be  0 <  fractionLast <= 1 " << G4endl;
  }
  if( (fractNext > 0.0) && (fractNext <1.0) )
  {
    fFractionNextEstimate = fractNext;
  }
  else
  {
    G4cerr << "G4ChordFinder:: SetFractions_Last_Next: Invalid "
           << " fraction Next = " << fractNext
           << " must be  0 <  fractionNext < 1 " << G4endl;
  }
}

void G4ChordFinder::SetIntegrationDriver

(

G4MagInt_Driver *

IntegrationDriver

)

[inline]

Definition at line 34 of file G4ChordFinder.icc.

{
  fIntgrDriver=IntegrationDriver;
}

void G4ChordFinder::SetLastStepEstimateUnc

(

G4double

stepEst

)

[inline, protected]

Definition at line 78 of file G4ChordFinder.icc.

Referenced by G4ChordFinderSaf::FindNextChord().

{
  fLastStepEstimate_Unconstrained = stepEst;    
}

G4int G4ChordFinder::SetVerbose

(

G4int

newvalue = 1

)

[inline]

Definition at line 102 of file G4ChordFinder.icc.

Referenced by G4ChordFinderSaf::~G4ChordFinderSaf().

{ 
  G4int oldval= fStatsVerbose; 
  fStatsVerbose = newvalue;
  return oldval; 
}

void G4ChordFinder::TestChordPrint	(	G4int	noTrials,
		G4int	lastStepTrial,
		G4double	dChordStep,
		G4double	nextStepTrial
	)

Definition at line 655 of file G4ChordFinder.cc.

References G4cout, and G4endl.

{
     G4int oldprec= G4cout.precision(5);
     G4cout << " ChF/fnc: notrial " << std::setw( 3) << noTrials 
            << " this_step= "       << std::setw(10) << lastStepTrial;
     if( std::fabs( (dChordStep / fDeltaChord) - 1.0 ) < 0.001 )
     {
       G4cout.precision(8);
     }
     else
     {
       G4cout.precision(6);
     }
     G4cout << " dChordStep=  " << std::setw(12) << dChordStep;
     if( dChordStep > fDeltaChord ) { G4cout << " d+"; }
     else                           { G4cout << " d-"; }
     G4cout.precision(5);
     G4cout <<  " new_step= "       << std::setw(10)
            << fLastStepEstimate_Unconstrained
            << " new_step_constr= " << std::setw(10)
            << lastStepTrial << G4endl;
     G4cout << " nextStepTrial = " << std::setw(10) << nextStepTrial << G4endl;
     G4cout.precision(oldprec);
}

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

• G4ChordFinder.hh
• G4ChordFinder.icc
• G4ChordFinder.cc

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