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geant4/source/geometry/magneticfield/include/G4InterpolationDriver.hh
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2020-06-26 10:23:25 +02:00

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//
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//
// G4InterpolationDriver
//
// Class description:
//
// Driver class which uses Runge-Kutta stepper with interpolation property
// to integrate track with error control
// Created: D.Sorokin, 2018
// --------------------------------------------------------------------
#ifndef G4INTERPOLATION_DRIVER_HH
#define G4INTERPOLATION_DRIVER_HH
#include "G4RKIntegrationDriver.hh"
#include "G4FieldUtils.hh"
#include "globals.hh"
#include <vector>
#include <memory>
template <class T>
class G4InterpolationDriver : public G4RKIntegrationDriver<T>
{
public:
G4InterpolationDriver(G4double hminimum,
T* stepper,
G4int numberOfComponents = 6,
G4int statisticsVerbosity = 0);
virtual ~G4InterpolationDriver() override;
G4InterpolationDriver(const G4InterpolationDriver&)= delete;
const G4InterpolationDriver& operator=(const G4InterpolationDriver&)= delete;
virtual G4double AdvanceChordLimited(G4FieldTrack& track,
G4double hstep,
G4double eps,
G4double chordDistance) override;
virtual void OnStartTracking() override;
virtual void OnComputeStep() override;
virtual G4bool DoesReIntegrate() const override { return false; }
// Interpolation driver does not recalculate when AccurateAdvance is called
// -- reintegration would require other calls
virtual G4bool AccurateAdvance(G4FieldTrack& track,
G4double hstep,
G4double eps, // Requested y_err/hstep
G4double hinitial = 0) override;
// Integrates ODE from current s (s=s0) to s=s0+h with accuracy eps.
// On output track is replaced by value at end of interval.
// The concept is similar to the odeint routine from NRC p.721-722.
virtual void SetVerboseLevel(G4int level) override;
virtual G4int GetVerboseLevel() const override;
virtual void StreamInfo( std::ostream& os ) const override;
private:
struct InterpStepper
{
std::unique_ptr<T> stepper;
G4double begin;
G4double end;
G4double inverseLength;
};
using StepperIterator = typename std::vector<InterpStepper>::iterator;
using ConstStepperIterator = typename std::vector<InterpStepper>::const_iterator;
G4double OneGoodStep(StepperIterator it,
field_utils::State& y,
field_utils::State& dydx,
G4double& hstep,
G4double eps,
G4double curveLength);
// This takes one Step that is of size htry, or as large
// as possible while satisfying the accuracy criterion of:
// yerr < eps * |y_end-y_start|
// return hdid
void Interpolate(G4double curveLength, field_utils::State& y) const;
void InterpolateImpl(G4double curveLength,
ConstStepperIterator it,
field_utils::State& y) const;
G4double DistChord(const field_utils::State& yBegin,
G4double curveLengthBegin,
const field_utils::State& yEnd,
G4double curveLengthEnd) const;
G4double FindNextChord(const field_utils::State& yBegin,
G4double curveLengthBegin,
field_utils::State& yEnd,
G4double curveLengthEnd,
G4double dChord,
G4double maxChordDistance);
G4double CalcChordStep(G4double stepTrialOld,
G4double dChordStep,
G4double fDeltaChord);
void PrintState() const;
void CheckState() const;
void AccumulateStatistics(G4int noTrials);
private:
std::vector<InterpStepper> fSteppers;
StepperIterator fLastStepper;
G4bool fKeepLastStepper = false;
G4double fhnext = DBL_MAX; // Memory of last good step size for integration
// Minimum Step allowed in a Step (in units of length) // Parameter
G4double fMinimumStep;
G4double fChordStepEstimate = DBL_MAX;
const G4double fFractionNextEstimate = 0.98; // Constant
const G4double fSmallestCurveFraction = 0.01; // Constant
G4int fVerboseLevel; // Parameter
field_utils::State fdydx;
G4bool fFirstStep = true;
const G4int fMaxTrials = 100; // Constant
G4int fTotalStepsForTrack = 0;
// statistics
G4int fTotalNoTrials = 0;
G4int fNoCalls = 0;
G4int fmaxTrials = 0;
using Base = G4RKIntegrationDriver<T>;
};
#include "G4InterpolationDriver.icc"
#endif