G4MagInt_Driver Class Reference

#include <G4MagIntegratorDriver.hh>

Public Member Functions
G4bool	AccurateAdvance (G4FieldTrack &y_current, G4double hstep, G4double eps, G4double hinitial=0.0)
G4bool	QuickAdvance (G4FieldTrack &y_val, const G4double dydx[], G4double hstep, G4double &dchord_step, G4double &dyerr)
G4bool	QuickAdvance (G4FieldTrack &y_posvel, const G4double dydx[], G4double hstep, G4double &dchord_step, G4double &dyerr_pos_sq, G4double &dyerr_mom_rel_sq)
	G4MagInt_Driver (G4double hminimum, G4MagIntegratorStepper *pItsStepper, G4int numberOfComponents=6, G4int statisticsVerbosity=1)
	~G4MagInt_Driver ()
G4double	GetHmin () const
G4double	Hmin () const
G4double	GetSafety () const
G4double	GetPshrnk () const
G4double	GetPgrow () const
G4double	GetErrcon () const
void	GetDerivatives (const G4FieldTrack &y_curr, G4double dydx[])
void	RenewStepperAndAdjust (G4MagIntegratorStepper *pItsStepper)
void	ReSetParameters (G4double new_safety=0.9)
void	SetSafety (G4double valS)
void	SetPshrnk (G4double valPs)
void	SetPgrow (G4double valPg)
void	SetErrcon (G4double valEc)
G4double	ComputeAndSetErrcon ()
const G4MagIntegratorStepper *	GetStepper () const
G4MagIntegratorStepper *	GetStepper ()
void	OneGoodStep (G4double ystart[], const G4double dydx[], G4double &x, G4double htry, G4double eps, G4double &hdid, G4double &hnext)
G4double	ComputeNewStepSize (G4double errMaxNorm, G4double hstepCurrent)
G4double	ComputeNewStepSize_WithinLimits (G4double errMaxNorm, G4double hstepCurrent)
G4int	GetMaxNoSteps () const
void	SetMaxNoSteps (G4int val)
void	SetHmin (G4double newval)
void	SetVerboseLevel (G4int newLevel)
G4double	GetVerboseLevel () const
G4double	GetSmallestFraction () const
void	SetSmallestFraction (G4double val)

Protected Member Functions
void	WarnSmallStepSize (G4double hnext, G4double hstep, G4double h, G4double xDone, G4int noSteps)
void	WarnTooManyStep (G4double x1start, G4double x2end, G4double xCurrent)
void	WarnEndPointTooFar (G4double endPointDist, G4double hStepSize, G4double epsilonRelative, G4int debugFlag)
void	PrintStatus (const G4double *StartArr, G4double xstart, const G4double *CurrentArr, G4double xcurrent, G4double requestStep, G4int subStepNo)
void	PrintStatus (const G4FieldTrack &StartFT, const G4FieldTrack &CurrentFT, G4double requestStep, G4int subStepNo)
void	PrintStat_Aux (const G4FieldTrack &aFieldTrack, G4double requestStep, G4double actualStep, G4int subStepNo, G4double subStepSize, G4double dotVelocities)
void	PrintStatisticsReport ()

Detailed Description

Definition at line 48 of file G4MagIntegratorDriver.hh.

Constructor & Destructor Documentation

G4MagInt_Driver::G4MagInt_Driver	(	G4double	hminimum,
		G4MagIntegratorStepper *	pItsStepper,
		G4int	numberOfComponents = 6,
		G4int	statisticsVerbosity = 1
	)

Definition at line 69 of file G4MagIntegratorDriver.cc.

References G4cout, G4endl, G4MagIntegratorStepper::IntegratorOrder(), and RenewStepperAndAdjust().

  : fSmallestFraction( 1.0e-12 ), 
    fNoIntegrationVariables(numComponents), 
    fMinNoVars(12), 
    fNoVars( std::max( fNoIntegrationVariables, fMinNoVars )),
    fStatisticsVerboseLevel(statisticsVerbose),
    fNoTotalSteps(0),  fNoBadSteps(0), fNoSmallSteps(0),
    fNoInitialSmallSteps(0), 
    fDyerr_max(0.0), fDyerr_mx2(0.0), 
    fDyerrPos_smTot(0.0), fDyerrPos_lgTot(0.0), fDyerrVel_lgTot(0.0), 
    fSumH_sm(0.0), fSumH_lg(0.0),
    fVerboseLevel(0)
{  
  // In order to accomodate "Laboratory Time", which is [7], fMinNoVars=8
  // is required. For proper time of flight and spin,  fMinNoVars must be 12

  RenewStepperAndAdjust( pStepper );
  fMinimumStep= hminimum;
  fMaxNoSteps = fMaxStepBase / pIntStepper->IntegratorOrder();
#ifdef G4DEBUG_FIELD
  fVerboseLevel=2;
#endif

  if( (fVerboseLevel > 0) || (fStatisticsVerboseLevel > 1) )
  {
    G4cout << "MagIntDriver version: Accur-Adv: "
           << "invE_nS, QuickAdv-2sqrt with Statistics "
#ifdef G4FLD_STATS
           << " enabled "
#else
           << " disabled "
#endif
           << G4endl;
  }
}

G4MagInt_Driver::~G4MagInt_Driver

(

)

Definition at line 112 of file G4MagIntegratorDriver.cc.

References PrintStatisticsReport().

{ 
  if( fStatisticsVerboseLevel > 1 )
  {
    PrintStatisticsReport();
  }
}

Member Function Documentation

G4bool G4MagInt_Driver::AccurateAdvance	(	G4FieldTrack &	y_current,
		G4double	hstep,
		G4double	eps,
		G4double	hinitial = 0.0
	)

Definition at line 127 of file G4MagIntegratorDriver.cc.

References ComputeNewStepSize(), G4MagIntegratorStepper::ComputeRightHandSide(), G4FieldTrack::DumpToArray(), EventMustBeAborted, FatalException, G4cerr, G4cout, G4endl, G4Exception(), G4ThreadLocal, G4FieldTrack::GetCurveLength(), Hmin(), JustWarning, G4FieldTrack::LoadFromArray(), G4FieldTrack::ncompSVEC, OneGoodStep(), python.hepunit::perMillion, python.hepunit::perThousand, PrintStatus(), QuickAdvance(), G4FieldTrack::SetCurveLength(), WarnEndPointTooFar(), WarnSmallStepSize(), WarnTooManyStep(), and test::x.

Referenced by G4ChordFinder::AdvanceChordLimited(), G4ChordFinder::ApproxCurvePointS(), G4ChordFinder::ApproxCurvePointV(), G4BrentLocator::EstimateIntersectionPoint(), G4MultiLevelLocator::EstimateIntersectionPoint(), and G4VIntersectionLocator::ReEstimateEndpoint().

{
  // Runge-Kutta driver with adaptive stepsize control. Integrate starting
  // values at y_current over hstep x2 with accuracy eps. 
  // On output ystart is replaced by values at the end of the integration 
  // interval. RightHandSide is the right-hand side of ODE system. 
  // The source is similar to odeint routine from NRC p.721-722 .

  G4int nstp, i, no_warnings=0;
  G4double x, hnext, hdid, h;

#ifdef G4DEBUG_FIELD
  static G4int dbg=1;
  static G4int nStpPr=50;   // For debug printing of long integrations
  G4double ySubStepStart[G4FieldTrack::ncompSVEC];
  G4FieldTrack  yFldTrkStart(y_current);
#endif

  G4double y[G4FieldTrack::ncompSVEC], dydx[G4FieldTrack::ncompSVEC];
  G4double ystart[G4FieldTrack::ncompSVEC], yEnd[G4FieldTrack::ncompSVEC]; 
  G4double  x1, x2;
  G4bool succeeded = true, lastStepSucceeded;

  G4double startCurveLength;

  G4int  noFullIntegr=0, noSmallIntegr = 0 ;
  static G4ThreadLocal G4int  noGoodSteps =0 ;  // Bad = chord > curve-len 
  const  G4int  nvar= fNoVars;

  G4FieldTrack yStartFT(y_current);

  //  Ensure that hstep > 0
  //
  if( hstep <= 0.0 )
  { 
    if(hstep==0.0)
    {
      std::ostringstream message;
      message << "Proposed step is zero; hstep = " << hstep << " !";
      G4Exception("G4MagInt_Driver::AccurateAdvance()", 
                  "GeomField1001", JustWarning, message);
      return succeeded; 
    }
    else
    { 
      std::ostringstream message;
      message << "Invalid run condition." << G4endl
              << "Proposed step is negative; hstep = " << hstep << "." << G4endl
              << "Requested step cannot be negative! Aborting event.";
      G4Exception("G4MagInt_Driver::AccurateAdvance()", 
                  "GeomField0003", EventMustBeAborted, message);
      return false;
    }
  }

  y_current.DumpToArray( ystart );

  startCurveLength= y_current.GetCurveLength();
  x1= startCurveLength; 
  x2= x1 + hstep;

  if ( (hinitial > 0.0) && (hinitial < hstep)
    && (hinitial > perMillion * hstep) )
  {
     h = hinitial;
  }
  else  //  Initial Step size "h" defaults to the full interval
  {
     h = hstep;
  }

  x = x1;

  for (i=0;i<nvar;i++)  { y[i] = ystart[i]; }

  G4bool lastStep= false;
  nstp=1;

  do
  {
    G4ThreeVector StartPos( y[0], y[1], y[2] );

#ifdef G4DEBUG_FIELD
    G4double xSubStepStart= x; 
    for (i=0;i<nvar;i++)  { ySubStepStart[i] = y[i]; }
    yFldTrkStart.LoadFromArray(y, fNoIntegrationVariables);
    yFldTrkStart.SetCurveLength(x);
#endif

    // Old method - inline call to Equation of Motion
    //   pIntStepper->RightHandSide( y, dydx );
    // New method allows to cache field, or state (eg momentum magnitude)
    pIntStepper->ComputeRightHandSide( y, dydx );
    fNoTotalSteps++;

    // Perform the Integration
    //      
    if( h > fMinimumStep )
    { 
      OneGoodStep(y,dydx,x,h,eps,hdid,hnext) ;
      //--------------------------------------
      lastStepSucceeded= (hdid == h);   
#ifdef G4DEBUG_FIELD
      if (dbg>2) {
        PrintStatus( ySubStepStart, xSubStepStart, y, x, h,  nstp); // Only
      }
#endif
    }
    else
    {
      G4FieldTrack yFldTrk( G4ThreeVector(0,0,0), 
                            G4ThreeVector(0,0,0), 0., 0., 0., 0. );
      G4double dchord_step, dyerr, dyerr_len;   // What to do with these ?
      yFldTrk.LoadFromArray(y, fNoIntegrationVariables); 
      yFldTrk.SetCurveLength( x );

      QuickAdvance( yFldTrk, dydx, h, dchord_step, dyerr_len ); 
      //-----------------------------------------------------

      yFldTrk.DumpToArray(y);    

#ifdef G4FLD_STATS
      fNoSmallSteps++; 
      if ( dyerr_len > fDyerr_max)  { fDyerr_max= dyerr_len; }
      fDyerrPos_smTot += dyerr_len;
      fSumH_sm += h;  // Length total for 'small' steps
      if (nstp<=1)  { fNoInitialSmallSteps++; }
#endif
#ifdef G4DEBUG_FIELD
      if (dbg>1)
      {
        if(fNoSmallSteps<2) { PrintStatus(ySubStepStart, x1, y, x, h, -nstp); }
        G4cout << "Another sub-min step, no " << fNoSmallSteps 
               << " of " << fNoTotalSteps << " this time " << nstp << G4endl; 
        PrintStatus( ySubStepStart, x1, y, x, h,  nstp);   // Only this
        G4cout << " dyerr= " << dyerr_len << " relative = " << dyerr_len / h 
               << " epsilon= " << eps << " hstep= " << hstep 
               << " h= " << h << " hmin= " << fMinimumStep << G4endl;
      }
#endif        
      if( h == 0.0 )
      { 
        G4Exception("G4MagInt_Driver::AccurateAdvance()",
                    "GeomField0003", FatalException,
                    "Integration Step became Zero!"); 
      }
      dyerr = dyerr_len / h;
      hdid= h;
      x += hdid;

      // Compute suggested new step
      hnext= ComputeNewStepSize( dyerr/eps, h);

      // .. hnext= ComputeNewStepSize_WithinLimits( dyerr/eps, h);
      lastStepSucceeded= (dyerr<= eps);
    }

    if (lastStepSucceeded)  { noFullIntegr++; }
    else                    { noSmallIntegr++; }

    G4ThreeVector EndPos( y[0], y[1], y[2] );

#ifdef  G4DEBUG_FIELD
    if( (dbg>0) && (dbg<=2) && (nstp>nStpPr))
    {
      if( nstp==nStpPr )  { G4cout << "***** Many steps ****" << G4endl; }
      G4cout << "MagIntDrv: " ; 
      G4cout << "hdid="  << std::setw(12) << hdid  << " "
             << "hnext=" << std::setw(12) << hnext << " " 
         << "hstep=" << std::setw(12) << hstep << " (requested) " 
         << G4endl;
      PrintStatus( ystart, x1, y, x, h, (nstp==nStpPr) ? -nstp: nstp); 
    }
#endif

    // Check the endpoint
    G4double endPointDist= (EndPos-StartPos).mag(); 
    if ( endPointDist >= hdid*(1.+perMillion) )
    {
      fNoBadSteps++;

      // Issue a warning only for gross differences -
      // we understand how small difference occur.
      if ( endPointDist >= hdid*(1.+perThousand) )
      { 
#ifdef G4DEBUG_FIELD
        if (dbg)
        {
          WarnEndPointTooFar ( endPointDist, hdid, eps, dbg ); 
          G4cerr << "  Total steps:  bad " << fNoBadSteps
                 << " good " << noGoodSteps << " current h= " << hdid
                 << G4endl;
          PrintStatus( ystart, x1, y, x, hstep, no_warnings?nstp:-nstp);  
        }
#endif
        no_warnings++;
      }
    }
    else
    {
      noGoodSteps ++;
    } 
// #endif

    //  Avoid numerous small last steps
    if( (h < eps * hstep) || (h < fSmallestFraction * startCurveLength) )
    {
      // No more integration -- the next step will not happen
      lastStep = true;  
    }
    else
    {
      // Check the proposed next stepsize
      if(std::fabs(hnext) <= Hmin())
      {
#ifdef  G4DEBUG_FIELD
        // If simply a very small interval is being integrated, do not warn
        if( (x < x2 * (1-eps) ) &&        // The last step can be small: OK
            (std::fabs(hstep) > Hmin()) ) // and if we are asked, it's OK
        {
          if(dbg>0)
          {
            WarnSmallStepSize( hnext, hstep, h, x-x1, nstp );  
            PrintStatus( ystart, x1, y, x, hstep, no_warnings?nstp:-nstp);
          }
          no_warnings++;
        }
#endif
        // Make sure that the next step is at least Hmin.
        h = Hmin();
      }
      else
      {
        h = hnext;
      }

      //  Ensure that the next step does not overshoot
      if ( x+h > x2 )
      {                // When stepsize overshoots, decrease it!
        h = x2 - x ;   // Must cope with difficult rounding-error
      }                // issues if hstep << x2

      if ( h == 0.0 )
      {
        // Cannot progress - accept this as last step - by default
        lastStep = true;
#ifdef G4DEBUG_FIELD
        if (dbg>2)
        {
          int prec= G4cout.precision(12); 
          G4cout << "Warning: G4MagIntegratorDriver::AccurateAdvance"
                 << G4endl
                 << "  Integration step 'h' became "
                 << h << " due to roundoff. " << G4endl
         << " Calculated as difference of x2= "<< x2 << " and x=" << x
                 << "  Forcing termination of advance." << G4endl;
          G4cout.precision(prec);
        }          
#endif
      }
    }
  } while ( ((nstp++)<=fMaxNoSteps) && (x < x2) && (!lastStep) );
     // Have we reached the end ?
     // --> a better test might be x-x2 > an_epsilon

  succeeded=  (x>=x2);  // If it was a "forced" last step

  for (i=0;i<nvar;i++)  { yEnd[i] = y[i]; }

  // Put back the values.
  y_current.LoadFromArray( yEnd, fNoIntegrationVariables );
  y_current.SetCurveLength( x );

  if(nstp > fMaxNoSteps)
  {
    no_warnings++;
    succeeded = false;
#ifdef G4DEBUG_FIELD
    if (dbg)
    {
      WarnTooManyStep( x1, x2, x );  //  Issue WARNING
      PrintStatus( yEnd, x1, y, x, hstep, -nstp);
    }
#endif
  }

#ifdef G4DEBUG_FIELD
  if( dbg && no_warnings )
  {
    G4cerr << "G4MagIntegratorDriver exit status: no-steps " << nstp <<G4endl;
    PrintStatus( yEnd, x1, y, x, hstep, nstp);
  }
#endif

  return succeeded;
}  // end of AccurateAdvance ...........................

G4double G4MagInt_Driver::ComputeAndSetErrcon ( )

inline

G4double G4MagInt_Driver::ComputeNewStepSize	(	G4double	errMaxNorm,
		G4double	hstepCurrent
	)

Definition at line 754 of file G4MagIntegratorDriver.cc.

References GetPgrow(), GetPshrnk(), and GetSafety().

Referenced by AccurateAdvance(), G4ChordFinderSaf::FindNextChord(), G4ChordFinder::FindNextChord(), and QuickAdvance().

{
  G4double hnew;

  // Compute size of next Step for a failed step
  if(errMaxNorm > 1.0 )
  {
    // Step failed; compute the size of retrial Step.
    hnew = GetSafety()*hstepCurrent*std::pow(errMaxNorm,GetPshrnk()) ;
  } else if(errMaxNorm > 0.0 ) {
    // Compute size of next Step for a successful step
    hnew = GetSafety()*hstepCurrent*std::pow(errMaxNorm,GetPgrow()) ;
  } else {
    // if error estimate is zero (possible) or negative (dubious)
    hnew = max_stepping_increase * hstepCurrent; 
  }

  return hnew;
}

G4double G4MagInt_Driver::ComputeNewStepSize_WithinLimits	(	G4double	errMaxNorm,
		G4double	hstepCurrent
	)

Definition at line 784 of file G4MagIntegratorDriver.cc.

References GetPgrow(), GetPshrnk(), and GetSafety().

{
  G4double hnew;

  // Compute size of next Step for a failed step
  if (errMaxNorm > 1.0 )
  {
    // Step failed; compute the size of retrial Step.
    hnew = GetSafety()*hstepCurrent*std::pow(errMaxNorm,GetPshrnk()) ;
  
    if (hnew < max_stepping_decrease*hstepCurrent)
    {
      hnew = max_stepping_decrease*hstepCurrent ;
                         // reduce stepsize, but no more
                         // than this factor (value= 1/10)
    }
  }
  else
  {
    // Compute size of next Step for a successful step
    if (errMaxNorm > errcon)
     { hnew = GetSafety()*hstepCurrent*std::pow(errMaxNorm,GetPgrow()); }
    else  // No more than a factor of 5 increase
     { hnew = max_stepping_increase * hstepCurrent; }
  }
  return hnew;
}

void G4MagInt_Driver::GetDerivatives ( const G4FieldTrack &  y_curr, G4double  dydx[]  )

inline

G4double G4MagInt_Driver::GetErrcon ( ) const

inline

G4double G4MagInt_Driver::GetHmin ( ) const

inline

G4int G4MagInt_Driver::GetMaxNoSteps ( ) const

inline

G4double G4MagInt_Driver::GetPgrow ( ) const

inline

Referenced by ComputeNewStepSize(), ComputeNewStepSize_WithinLimits(), and OneGoodStep().

G4double G4MagInt_Driver::GetPshrnk ( ) const

inline

Referenced by ComputeNewStepSize(), ComputeNewStepSize_WithinLimits(), and OneGoodStep().

G4double G4MagInt_Driver::GetSafety ( ) const

inline

Referenced by ComputeNewStepSize(), ComputeNewStepSize_WithinLimits(), and OneGoodStep().

G4double G4MagInt_Driver::GetSmallestFraction ( ) const

inline

const G4MagIntegratorStepper* G4MagInt_Driver::GetStepper ( ) const

inline

Referenced by G4Transportation::AlongStepGetPhysicalInteractionLength(), G4CoupledTransportation::AlongStepGetPhysicalInteractionLength(), G4MonopoleTransportation::AlongStepGetPhysicalInteractionLength(), and G4ErrorPropagatorManager::InitFieldForBackwards().

G4MagIntegratorStepper* G4MagInt_Driver::GetStepper ( )

inline

G4double G4MagInt_Driver::GetVerboseLevel ( ) const

inline

G4double G4MagInt_Driver::Hmin ( ) const

inline

Referenced by AccurateAdvance(), and WarnSmallStepSize().

void G4MagInt_Driver::OneGoodStep	(	G4double	ystart[],
		const G4double	dydx[],
		G4double &	x,
		G4double	htry,
		G4double	eps,
		G4double &	hdid,
		G4double &	hnext
	)

Definition at line 515 of file G4MagIntegratorDriver.cc.

References G4cerr, G4endl, G4ThreadLocal, GetPgrow(), GetPshrnk(), GetSafety(), CLHEP::Hep3Vector::mag2(), G4INCL::Math::max(), G4FieldTrack::ncompSVEC, and sqr().

Referenced by AccurateAdvance().

{
  G4double errmax_sq;
  G4double h, htemp, xnew ;

  G4double yerr[G4FieldTrack::ncompSVEC], ytemp[G4FieldTrack::ncompSVEC];

  h = htry ; // Set stepsize to the initial trial value

  G4double inv_eps_vel_sq = 1.0 / (eps_rel_max*eps_rel_max);

  G4double errpos_sq=0.0;    // square of displacement error
  G4double errvel_sq=0.0;    // square of momentum vector difference
  G4double errspin_sq=0.0;   // square of spin vector difference

  G4int iter;

  static G4ThreadLocal G4int tot_no_trials=0; 
  const G4int max_trials=100; 

  G4ThreeVector Spin(y[9],y[10],y[11]);
  G4bool     hasSpin= (Spin.mag2() > 0.0); 

  for (iter=0; iter<max_trials ;iter++)
  {
    tot_no_trials++;
    pIntStepper-> Stepper(y,dydx,h,ytemp,yerr); 
    //            *******
    G4double eps_pos = eps_rel_max * std::max(h, fMinimumStep); 
    G4double inv_eps_pos_sq = 1.0 / (eps_pos*eps_pos); 

    // Evaluate accuracy
    //
    errpos_sq =  sqr(yerr[0]) + sqr(yerr[1]) + sqr(yerr[2]) ;
    errpos_sq *= inv_eps_pos_sq; // Scale relative to required tolerance

    // Accuracy for momentum
    errvel_sq =  (sqr(yerr[3]) + sqr(yerr[4]) + sqr(yerr[5]) )
               / (sqr(y[3]) + sqr(y[4]) + sqr(y[5]) );
    errvel_sq *= inv_eps_vel_sq;
    errmax_sq = std::max( errpos_sq, errvel_sq ); // Square of maximum error

    if( hasSpin )
    { 
      // Accuracy for spin
      errspin_sq =  ( sqr(yerr[9]) + sqr(yerr[10]) + sqr(yerr[11]) )
                 /  ( sqr(y[9]) + sqr(y[10]) + sqr(y[11]) );
      errspin_sq *= inv_eps_vel_sq;
      errmax_sq = std::max( errmax_sq, errspin_sq ); 
   }

    if ( errmax_sq <= 1.0 )  { break; } // Step succeeded. 

    // Step failed; compute the size of retrial Step.
    htemp = GetSafety()*h* std::pow( errmax_sq, 0.5*GetPshrnk() );

    if (htemp >= 0.1*h)  { h = htemp; }  // Truncation error too large,
    else  { h = 0.1*h; }                 // reduce stepsize, but no more
                                         // than a factor of 10
    xnew = x + h;
    if(xnew == x)
    {
      G4cerr << "G4MagIntegratorDriver::OneGoodStep:" << G4endl
             << "  Stepsize underflow in Stepper " << G4endl ;
      G4cerr << "  Step's start x=" << x << " and end x= " << xnew 
             << " are equal !! " << G4endl
             <<"  Due to step-size= " << h 
             << " . Note that input step was " << htry << G4endl;
      break;
    }
  }

#ifdef G4FLD_STATS
  // Sum of squares of position error // and momentum dir (underestimated)
  fSumH_lg += h; 
  fDyerrPos_lgTot += errpos_sq;
  fDyerrVel_lgTot += errvel_sq * h * h; 
#endif

  // Compute size of next Step
  if (errmax_sq > errcon*errcon)
  { 
    hnext = GetSafety()*h*std::pow(errmax_sq, 0.5*GetPgrow());
  }
  else
  {
    hnext = max_stepping_increase*h ; // No more than a factor of 5 increase
  }
  x += (hdid = h);

  for(G4int k=0;k<fNoIntegrationVariables;k++) { y[k] = ytemp[k]; }

  return;
}   // end of  OneGoodStep .............................

void G4MagInt_Driver::PrintStat_Aux ( const G4FieldTrack &  aFieldTrack, G4double  requestStep, G4double  actualStep, G4int  subStepNo, G4double  subStepSize, G4double  dotVelocities  )

protected

Definition at line 919 of file G4MagIntegratorDriver.cc.

References G4cout, G4endl, G4ThreadLocal, G4FieldTrack::GetCurveLength(), G4FieldTrack::GetKineticEnergy(), G4FieldTrack::GetMomentumDir(), G4FieldTrack::GetPosition(), CLHEP::Hep3Vector::mag2(), CLHEP::Hep3Vector::x(), CLHEP::Hep3Vector::y(), and CLHEP::Hep3Vector::z().

Referenced by PrintStatus().

{
    const G4ThreeVector Position=      aFieldTrack.GetPosition();
    const G4ThreeVector UnitVelocity=  aFieldTrack.GetMomentumDir();
 
    if( subStepNo >= 0)
    {
       G4cout << std::setw( 5) << subStepNo << " ";
    }
    else
    {
       G4cout << std::setw( 5) << "Start" << " ";
    }
    G4double curveLen= aFieldTrack.GetCurveLength();
    G4cout << std::setw( 7) << curveLen;
    G4cout << std::setw( 9) << Position.x() << " "
           << std::setw( 9) << Position.y() << " "
           << std::setw( 9) << Position.z() << " "
           << std::setw( 8) << UnitVelocity.x() << " "
           << std::setw( 8) << UnitVelocity.y() << " "
           << std::setw( 8) << UnitVelocity.z() << " ";
    G4int oldprec= G4cout.precision(3);
    G4cout << std::setw( 8) << UnitVelocity.mag2()-1.0 << " ";
    G4cout.precision(6);
    G4cout << std::setw(10) << dotVeloc_StartCurr << " ";
    G4cout.precision(oldprec);
    G4cout << std::setw( 7) << aFieldTrack.GetKineticEnergy();
    G4cout << std::setw(12) << step_len << " ";

    static G4ThreadLocal G4double oldCurveLength= 0.0;
    static G4ThreadLocal G4double oldSubStepLength= 0.0;
    static G4ThreadLocal G4int oldSubStepNo= -1;

    G4double subStep_len=0.0;
    if( curveLen > oldCurveLength )
    {
      subStep_len= curveLen - oldCurveLength;
    }
    else if (subStepNo == oldSubStepNo)
    {
      subStep_len= oldSubStepLength;
    }
    oldCurveLength= curveLen;
    oldSubStepLength= subStep_len;

    G4cout << std::setw(12) << subStep_len << " "; 
    G4cout << std::setw(12) << subStepSize << " "; 
    if( requestStep != -1.0 )
    {
      G4cout << std::setw( 9) << requestStep << " ";
    }
    else
    {
       G4cout << std::setw( 9) << " InitialStep " << " ";
    }
    G4cout << G4endl;
}

void G4MagInt_Driver::PrintStatisticsReport ( )

protected

Definition at line 985 of file G4MagIntegratorDriver.cc.

References G4cout, and G4endl.

Referenced by ~G4MagInt_Driver().

{
  G4int noPrecBig= 6;
  G4int oldPrec= G4cout.precision(noPrecBig);

  G4cout << "G4MagInt_Driver Statistics of steps undertaken. " << G4endl;
  G4cout << "G4MagInt_Driver: Number of Steps: "
         << " Total= " <<  fNoTotalSteps
         << " Bad= "   <<  fNoBadSteps 
         << " Small= " <<  fNoSmallSteps 
         << " Non-initial small= " << (fNoSmallSteps-fNoInitialSmallSteps)
         << G4endl;

#ifdef G4FLD_STATS
  G4cout << "MID dyerr: " 
         << " maximum= " << fDyerr_max 
         << " Sum small= " << fDyerrPos_smTot 
         << " std::sqrt(Sum large^2): pos= " << std::sqrt(fDyerrPos_lgTot)
         << " vel= " << std::sqrt( fDyerrVel_lgTot )
         << " Total h-distance: small= " << fSumH_sm 
         << " large= " << fSumH_lg
         << G4endl;

#if 0
  G4int noPrecSmall=4; 
  // Single line precis of statistics ... optional
  G4cout.precision(noPrecSmall);
  G4cout << "MIDnums: " << fMinimumStep
         << "   " << fNoTotalSteps 
         << "  "  <<  fNoSmallSteps
         << "  "  << fNoSmallSteps-fNoInitialSmallSteps
         << "  "  << fNoBadSteps         
         << "   " << fDyerr_max
         << "   " << fDyerr_mx2 
         << "   " << fDyerrPos_smTot 
         << "   " << fSumH_sm
         << "   " << fDyerrPos_lgTot
         << "   " << fDyerrVel_lgTot
         << "   " << fSumH_lg
         << G4endl;
#endif 
#endif 

 G4cout.precision(oldPrec);
}

void G4MagInt_Driver::PrintStatus ( const G4double *  StartArr, G4double  xstart, const G4double *  CurrentArr, G4double  xcurrent, G4double  requestStep, G4int  subStepNo  )

protected

Definition at line 816 of file G4MagIntegratorDriver.cc.

References G4FieldTrack::LoadFromArray(), and G4FieldTrack::SetCurveLength().

Referenced by AccurateAdvance(), and QuickAdvance().

{
   G4FieldTrack  StartFT(G4ThreeVector(0,0,0),
                 G4ThreeVector(0,0,0), 0., 0., 0., 0. );
   G4FieldTrack  CurrentFT (StartFT);

   StartFT.LoadFromArray( StartArr, fNoIntegrationVariables); 
   StartFT.SetCurveLength( xstart);
   CurrentFT.LoadFromArray( CurrentArr, fNoIntegrationVariables); 
   CurrentFT.SetCurveLength( xcurrent );

   PrintStatus(StartFT, CurrentFT, requestStep, subStepNo ); 
}

void G4MagInt_Driver::PrintStatus ( const G4FieldTrack &  StartFT, const G4FieldTrack &  CurrentFT, G4double  requestStep, G4int  subStepNo  )

protected

Definition at line 841 of file G4MagIntegratorDriver.cc.

References CLHEP::Hep3Vector::dot(), G4cout, G4endl, G4ThreadLocal, G4FieldTrack::GetCurveLength(), G4FieldTrack::GetMomentumDir(), G4FieldTrack::GetPosition(), and PrintStat_Aux().

{
    G4int verboseLevel= fVerboseLevel;
    static G4ThreadLocal G4int noPrecision= 5;
    G4int oldPrec= G4cout.precision(noPrecision);
    // G4cout.setf(ios_base::fixed,ios_base::floatfield);

    const G4ThreeVector StartPosition=       StartFT.GetPosition();
    const G4ThreeVector StartUnitVelocity=   StartFT.GetMomentumDir();
    const G4ThreeVector CurrentPosition=     CurrentFT.GetPosition();
    const G4ThreeVector CurrentUnitVelocity= CurrentFT.GetMomentumDir();

    G4double  DotStartCurrentVeloc= StartUnitVelocity.dot(CurrentUnitVelocity);

    G4double step_len= CurrentFT.GetCurveLength() - StartFT.GetCurveLength();
    G4double subStepSize = step_len;
     
    if( (subStepNo <= 1) || (verboseLevel > 3) )
    {
       subStepNo = - subStepNo;        // To allow printing banner

       G4cout << std::setw( 6)  << " " << std::setw( 25)
              << " G4MagInt_Driver: Current Position  and  Direction" << " "
              << G4endl; 
       G4cout << std::setw( 5) << "Step#" << " "
              << std::setw( 7) << "s-curve" << " "
              << std::setw( 9) << "X(mm)" << " "
              << std::setw( 9) << "Y(mm)" << " "  
              << std::setw( 9) << "Z(mm)" << " "
              << std::setw( 8) << " N_x " << " "
              << std::setw( 8) << " N_y " << " "
              << std::setw( 8) << " N_z " << " "
              << std::setw( 8) << " N^2-1 " << " "
              << std::setw(10) << " N(0).N " << " "
              << std::setw( 7) << "KinEner " << " "
              << std::setw(12) << "Track-l" << " "   // Add the Sub-step ??
              << std::setw(12) << "Step-len" << " " 
              << std::setw(12) << "Step-len" << " " 
              << std::setw( 9) << "ReqStep" << " "  
              << G4endl;
    }

    if( (subStepNo <= 0) )
    {
      PrintStat_Aux( StartFT,  requestStep, 0., 
                       0,        0.0,         1.0);
      //*************
    }

    if( verboseLevel <= 3 )
    {
      G4cout.precision(noPrecision);
      PrintStat_Aux( CurrentFT, requestStep, step_len, 
                     subStepNo, subStepSize, DotStartCurrentVeloc );
      //*************
    }

    else // if( verboseLevel > 3 )
    {
       //  Multi-line output
       
       // G4cout << "Current  Position is " << CurrentPosition << G4endl 
       //    << " and UnitVelocity is " << CurrentUnitVelocity << G4endl;
       // G4cout << "Step taken was " << step_len  
       //    << " out of PhysicalStep= " <<  requestStep << G4endl;
       // G4cout << "Final safety is: " << safety << G4endl;
       // G4cout << "Chord length = " << (CurrentPosition-StartPosition).mag()
       //        << G4endl << G4endl; 
    }
    G4cout.precision(oldPrec);
}

G4bool G4MagInt_Driver::QuickAdvance	(	G4FieldTrack &	y_val,
		const G4double	dydx[],
		G4double	hstep,
		G4double &	dchord_step,
		G4double &	dyerr
	)

Definition at line 653 of file G4MagIntegratorDriver.cc.

References ComputeNewStepSize(), G4FieldTrack::DumpToArray(), G4cout, G4endl, G4ThreadLocal, G4FieldTrack::GetCurveLength(), G4FieldTrack::LoadFromArray(), G4FieldTrack::ncompSVEC, PrintStatus(), G4FieldTrack::SetCurveLength(), and sqr().

Referenced by AccurateAdvance(), G4ChordFinderSaf::FindNextChord(), and G4ChordFinder::FindNextChord().

{
  G4double dyerr_pos_sq, dyerr_mom_rel_sq;  
  G4double yerr_vec[G4FieldTrack::ncompSVEC],
           yarrin[G4FieldTrack::ncompSVEC], yarrout[G4FieldTrack::ncompSVEC]; 
  G4double s_start;
  G4double dyerr_mom_sq, vel_mag_sq, inv_vel_mag_sq;

  static G4ThreadLocal G4int no_call=0; 
  no_call ++; 

  // Move data into array
  y_posvel.DumpToArray( yarrin );      //  yarrin  <== y_posvel 
  s_start = y_posvel.GetCurveLength();

  // Do an Integration Step
  pIntStepper-> Stepper(yarrin, dydx, hstep, yarrout, yerr_vec) ; 
  //            *******

  // Estimate curve-chord distance
  dchord_step= pIntStepper-> DistChord();
  //                         *********

  // Put back the values.  yarrout ==> y_posvel
  y_posvel.LoadFromArray( yarrout, fNoIntegrationVariables );
  y_posvel.SetCurveLength( s_start + hstep );

#ifdef  G4DEBUG_FIELD
  if(fVerboseLevel>2)
  {
    G4cout << "G4MagIntDrv: Quick Advance" << G4endl;
    PrintStatus( yarrin, s_start, yarrout, s_start+hstep, hstep,  1); 
  }
#endif

  // A single measure of the error   
  //      TO-DO :  account for  energy,  spin, ... ? 
  vel_mag_sq   = ( sqr(yarrout[3])+sqr(yarrout[4])+sqr(yarrout[5]) );
  inv_vel_mag_sq = 1.0 / vel_mag_sq; 
  dyerr_pos_sq = ( sqr(yerr_vec[0])+sqr(yerr_vec[1])+sqr(yerr_vec[2]));
  dyerr_mom_sq = ( sqr(yerr_vec[3])+sqr(yerr_vec[4])+sqr(yerr_vec[5]));
  dyerr_mom_rel_sq = dyerr_mom_sq * inv_vel_mag_sq;

  // Calculate also the change in the momentum squared also ???
  // G4double veloc_square = y_posvel.GetVelocity().mag2();
  // ...

#ifdef RETURN_A_NEW_STEP_LENGTH
  // The following step cannot be done here because "eps" is not known.
  dyerr_len = std::sqrt( dyerr_len_sq ); 
  dyerr_len_sq /= eps ;

  // Look at the velocity deviation ?
  //  sqr(yerr_vec[3])+sqr(yerr_vec[4])+sqr(yerr_vec[5]));

  // Set suggested new step
  hstep= ComputeNewStepSize( dyerr_len, hstep);
#endif

  if( dyerr_pos_sq > ( dyerr_mom_rel_sq * sqr(hstep) ) )
  {
    dyerr = std::sqrt(dyerr_pos_sq);
  }
  else
  {
    // Scale it to the current step size - for now
    dyerr = std::sqrt(dyerr_mom_rel_sq) * hstep;
  }

  return true;
}

G4bool G4MagInt_Driver::QuickAdvance	(	G4FieldTrack &	y_posvel,
		const G4double	dydx[],
		G4double	hstep,
		G4double &	dchord_step,
		G4double &	dyerr_pos_sq,
		G4double &	dyerr_mom_rel_sq
	)

Definition at line 634 of file G4MagIntegratorDriver.cc.

References FatalException, G4Exception(), G4FieldTrack::GetPosition(), and CLHEP::Hep3Vector::mag2().

{
  G4Exception("G4MagInt_Driver::QuickAdvance()", "GeomField0001",
              FatalException, "Not yet implemented."); 

  // Use the parameters of this method, to please compiler
  dchord_step = dyerr_pos_sq = hstep * hstep * dydx[0]; 
  dyerr_mom_rel_sq = y_posvel.GetPosition().mag2();
  return true;
}

void G4MagInt_Driver::RenewStepperAndAdjust ( G4MagIntegratorStepper *  pItsStepper )

inline

Referenced by G4MagInt_Driver().

void G4MagInt_Driver::ReSetParameters ( G4double  new_safety = 0.9 )

inline

void G4MagInt_Driver::SetErrcon ( G4double  valEc )

inline

void G4MagInt_Driver::SetHmin ( G4double  newval )

inline

void G4MagInt_Driver::SetMaxNoSteps ( G4int  val )

inline

void G4MagInt_Driver::SetPgrow ( G4double  valPg )

inline

void G4MagInt_Driver::SetPshrnk ( G4double  valPs )

inline

void G4MagInt_Driver::SetSafety ( G4double  valS )

inline

void G4MagInt_Driver::SetSmallestFraction

(

G4double

val

)

Definition at line 1033 of file G4MagIntegratorDriver.cc.

References G4cerr, and G4endl.

{
  if( (newFraction > 1.e-16) && (newFraction < 1e-8) )
  {
    fSmallestFraction= newFraction;
  }
  else
  { 
    G4cerr << "Warning: SmallestFraction not changed. " << G4endl
           << "  Proposed value was " << newFraction << G4endl
           << "  Value must be between 1.e-8 and 1.e-16" << G4endl;
  }
}

void G4MagInt_Driver::SetVerboseLevel ( G4int  newLevel )

inline

Referenced by G4PropagatorInField::SetVerboseLevel().

void G4MagInt_Driver::WarnEndPointTooFar ( G4double  endPointDist, G4double  hStepSize, G4double  epsilonRelative, G4int  debugFlag  )

protected

Definition at line 479 of file G4MagIntegratorDriver.cc.

References G4endl, G4Exception(), G4ThreadLocal, G4GeometryTolerance::GetInstance(), G4GeometryTolerance::GetSurfaceTolerance(), and JustWarning.

Referenced by AccurateAdvance().

{
  static G4ThreadLocal G4double maxRelError=0.0;
  G4bool isNewMax, prNewMax;

  isNewMax = endPointDist > (1.0 + maxRelError) * h;
  prNewMax = endPointDist > (1.0 + 1.05 * maxRelError) * h;
  if( isNewMax ) { maxRelError= endPointDist / h - 1.0; }

  if( dbg && (h > G4GeometryTolerance::GetInstance()->GetSurfaceTolerance()) 
          && ( (dbg>1) || prNewMax || (endPointDist >= h*(1.+eps) ) ) )
  { 
    static G4ThreadLocal G4int noWarnings = 0;
    std::ostringstream message;
    if( (noWarnings ++ < 10) || (dbg>2) )
    {
      message << "The integration produced an end-point which " << G4endl
              << "is further from the start-point than the curve length."
              << G4endl;
    }
    message << "  Distance of endpoints = " << endPointDist
            << ", curve length = " << h << G4endl
            << "  Difference (curveLen-endpDist)= " << (h - endPointDist)
            << ", relative = " << (h-endPointDist) / h 
            << ", epsilon =  " << eps;
    G4Exception("G4MagInt_Driver::WarnEndPointTooFar()", "GeomField1001",
                JustWarning, message);
  }
}

void G4MagInt_Driver::WarnSmallStepSize ( G4double  hnext, G4double  hstep, G4double  h, G4double  xDone, G4int  noSteps  )

protected

Definition at line 430 of file G4MagIntegratorDriver.cc.

References G4endl, G4Exception(), G4ThreadLocal, Hmin(), and JustWarning.

Referenced by AccurateAdvance().

{
  static G4ThreadLocal G4int noWarningsIssued =0;
  const  G4int maxNoWarnings =  10;   // Number of verbose warnings
  std::ostringstream message;
  if( (noWarningsIssued < maxNoWarnings) || fVerboseLevel > 10 )
  {
    message << "The stepsize for the next iteration, " << hnext
            << ", is too small - in Step number " << nstp << "." << G4endl
            << "The minimum for the driver is " << Hmin()  << G4endl
            << "Requested integr. length was " << hstep << " ." << G4endl
            << "The size of this sub-step was " << h     << " ." << G4endl
            << "The integrations has already gone " << xDone;
  }
  else
  {
    message << "Too small 'next' step " << hnext
            << ", step-no: " << nstp << G4endl
            << ", this sub-step: " << h     
            << ",  req_tot_len: " << hstep 
            << ", done: " << xDone << ", min: " << Hmin();
  }
  G4Exception("G4MagInt_Driver::WarnSmallStepSize()", "GeomField1001",
              JustWarning, message);
  noWarningsIssued++;
}

void G4MagInt_Driver::WarnTooManyStep ( G4double  x1start, G4double  x2end, G4double  xCurrent  )

protected

Definition at line 462 of file G4MagIntegratorDriver.cc.

References G4endl, G4Exception(), and JustWarning.

Referenced by AccurateAdvance().

{
    std::ostringstream message;
    message << "The number of steps used in the Integration driver"
            << " (Runge-Kutta) is too many." << G4endl
            << "Integration of the interval was not completed !" << G4endl
            << "Only a " << (xCurrent-x1start)*100/(x2end-x1start)
            << " % fraction of it was done.";
    G4Exception("G4MagInt_Driver::WarnTooManyStep()", "GeomField1001",
                JustWarning, message);
}

---

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

• G4MagIntegratorDriver.hh
• G4MagIntegratorDriver.cc