include/Geant4/G4QSSDriver.icc

0001 //
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0024 // ********************************************************************
0025 //
0026 // Authors: Lucio Santi, Rodrigo Castro (Univ. Buenos Aires) - 2018-2021
0027 // --------------------------------------------------------------------
0028
0029 template <class T>
0030 G4QSSDriver<T>::G4QSSDriver(T* pStepper) : G4InterpolationDriver<T, true>(0, pStepper)
0031 {
0032   // TODO: Remove additional stepper instances - should be a separate Driver class
0033   this->fSteppers.resize(1);
0034 }
0035
0036 template <class T>
0037 void G4QSSDriver<T>::OnStartTracking()
0038 {
0039   Base::OnStartTracking();
0040   if (! initializedOnFirstRun) {
0041     // this->SetPrecision( G4QSSMessenger::instance()->dQRel, G4QSSMessenger::instance()->dQMin);
0042
0043     G4double dqRel = G4QSSMessenger::instance()->dQRel;
0044     G4double dQMin = G4QSSMessenger::instance()->dQMin;
0045     if (dqRel == 0) {
0046       dqRel = 0.001;
0047     }
0048     if (dQMin == 0) {
0049       dQMin = 0.0001;
0050     }
0051     this->SetPrecision(dqRel, dQMin);
0052
0053     initializedOnFirstRun = true;
0054   }
0055 }
0056
0057 template <class T>
0058 void G4QSSDriver<T>::SetPrecision(G4double dq_rel, G4double dq_min)
0059 {
0060   G4cout << "Setting QSS precision parameters: "
0061          << "dQRel = " << dq_rel << " - "
0062          << "dQMin = " << dq_min << G4endl;
0063
0064   for (const auto& item : this->fSteppers) {
0065     item.stepper->SetPrecision(dq_rel, dq_min);
0066   }
0067 }
0068
0069 template <class T>
0070 G4double G4QSSDriver<T>::AdvanceChordLimited(
0071   G4FieldTrack& track, G4double hstep, G4double epsStep, G4double chordDistance)
0072 {
0073   // For now, just extract functionality that we don't use from G4InterpolationDriver
0074   // We should probably end up making  a custom G4QSSDriver separated from it
0075   ++this->fTotalStepsForTrack;
0076   this->fLastStepper = this->fSteppers.begin();
0077
0078   const G4double preCurveLength = track.GetCurveLength();
0079   G4double postCurveLength = preCurveLength;
0080   auto it = this->fSteppers.begin();
0081
0082   it->stepper->reset(const_cast<const G4FieldTrack*>(&track));
0083
0084   field_utils::State yBegin, y;
0085   track.DumpToArray(yBegin);
0086   track.DumpToArray(y);
0087
0088   G4double hdid = OneGoodStep(it, y, this->fdydx, hstep, epsStep, preCurveLength, &track);
0089   postCurveLength += hdid;
0090
0091   G4double dChordStep = this->DistChord(yBegin, preCurveLength, y, postCurveLength);
0092
0093   // update chord step estimate
0094   hdid = this->FindNextChord(
0095     yBegin, preCurveLength, y, postCurveLength, dChordStep, chordDistance);
0096
0097   track.LoadFromArray(y, this->fSteppers[0].stepper->GetNumberOfVariables());
0098   track.SetCurveLength(preCurveLength + hdid);
0099
0100   return hdid;
0101 }
0102
0103 template <class T>
0104 G4double G4QSSDriver<T>::OneGoodStep(typename G4InterpolationDriver<T, true>::StepperIterator it,
0105   field_utils::State& y, field_utils::State& dydx, G4double& hstep, G4double /*epsStep*/,
0106   G4double curveLength, G4FieldTrack* /*track*/)
0107 {
0108   G4double yerr[G4FieldTrack::ncompSVEC], ytemp[G4FieldTrack::ncompSVEC];
0109   it->stepper->Stepper(y, dydx, hstep, ytemp, yerr);
0110   G4double h = it->stepper->GetLastStepLength();
0111
0112   // set interpolation interval
0113   it->begin = curveLength;
0114   it->end = curveLength + h;
0115   it->inverseLength = 1. / h;
0116
0117   field_utils::copy(y, ytemp);
0118
0119   return h;
0120 }