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	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 47 of file G4ChordFinder.cc.

  : 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
}

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

Definition at line 71 of file G4ChordFinder.cc.

  : 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);   // The old default
         // new G4CashKarpRKF45(pEquation);
         // new G4DormandPrince745(pEquation); 
         // new G4BogackiShampine45(pEquation);

     fAllocatedStepper= true;
  }
  else
  {
     fAllocatedStepper= false; 
  }
  fIntgrDriver = new G4MagInt_Driver(stepMinimum, pItsStepper, 
                                     pItsStepper->GetNumberOfVariables() );
}

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G4ChordFinder::~G4ChordFinder ( )

virtual

Definition at line 119 of file G4ChordFinder.cc.

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

  if( fStatsVerbose ) { PrintStatistics(); }
}

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Member Function Documentation

G4bool G4ChordFinder::AcceptableMissDist ( G4double  dChordStep ) const

inlineprotected

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void G4ChordFinder::AccumulateStatistics ( G4int  noTrials )

inlineprotected

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

Definition at line 180 of file G4ChordFinder.cc.

{
  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;
}

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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 437 of file G4ChordFinder.cc.

{
  // 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;
}

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

Definition at line 549 of file G4ChordFinder.cc.

{
  // 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;
}

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

protectedvirtual

Reimplemented in G4ChordFinderSaf.

Definition at line 225 of file G4ChordFinder.cc.

{
  // 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 );

  unsigned int        noTrials=0;
  const unsigned int  maxTrials= 75; // Avoid endless loop for bad convergence 

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

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

  G4double newStepEst_Uncons= 0.0; 
  G4double stepForChord;
  do
  { 
     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) && (noTrials < maxTrials) );
  // Loop checking, 07.10.2016, J. Apostolakis

  if( noTrials >= maxTrials )
  {
      std::ostringstream message;
      message << "Exceeded maximum number of trials= " << maxTrials << G4endl
              << "Current sagita dist= " << dChordStep << G4endl
              << "Step sizes (actual and proposed): " << G4endl
              << "Last trial =         " << lastStepLength  << G4endl
              << "Next trial =         " << stepTrial  << G4endl
              << "Proposed for chord = " << stepForChord  << G4endl              
              ;
      G4Exception("G4ChordFinder::FindNextChord()", "GeomField0003",
                  JustWarning, message);
  }

  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; 
}

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G4double G4ChordFinder::GetDeltaChord ( ) const

inline

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G4double G4ChordFinder::GetFirstFraction ( )

inline

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G4double G4ChordFinder::GetFractionLast ( )

inline

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G4double G4ChordFinder::GetFractionNextEstimate ( )

inline

G4MagInt_Driver* G4ChordFinder::GetIntegrationDriver ( )

inline

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G4double G4ChordFinder::GetLastStepEstimateUnc ( )

inlineprotected

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G4double G4ChordFinder::GetMultipleRadius ( )

inline

G4int G4ChordFinder::GetNoCalls ( )

inline

G4int G4ChordFinder::GetNoMaxTrials ( )

inline

G4int G4ChordFinder::GetNoTrials ( )

inline

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

inline

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G4double G4ChordFinder::NewStep ( G4double  stepTrialOld, G4double  dChordStep, G4double &  stepEstimate_Unconstrained  )

protected

Definition at line 349 of file G4ChordFinder.cc.

{
  // 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;
}

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

protected

void G4ChordFinder::PrintStatistics ( )

virtual

Reimplemented in G4ChordFinderSaf.

Definition at line 658 of file G4ChordFinder.cc.

{
  // 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; 
}

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void G4ChordFinder::ResetStepEstimate ( )

inline

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void G4ChordFinder::SetDeltaChord ( G4double  newval )

inline

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void G4ChordFinder::SetFirstFraction ( G4double  fractFirst )

inline

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

Definition at line 135 of file G4ChordFinder.cc.

{ 
  // 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;
  }
}

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void G4ChordFinder::SetIntegrationDriver ( G4MagInt_Driver *  IntegrationDriver )

inline

void G4ChordFinder::SetLastStepEstimateUnc ( G4double  stepEst )

inlineprotected

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G4int G4ChordFinder::SetVerbose ( G4int  newvalue = 1 )

inline

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

Definition at line 679 of file G4ChordFinder.cc.

{
     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);
}

---

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

• source/geant4.10.03.p03/source/geometry/magneticfield/include/G4ChordFinder.hh
• source/geant4.10.03.p03/source/geometry/magneticfield/src/G4ChordFinder.cc