Gabriele Cosmo
136 lines
4.4 KiB
C++
136 lines
4.4 KiB
C++
// ********************************************************************
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// * License and Disclaimer *
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// * *
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// * The Geant4 software is copyright of the Copyright Holders of *
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// * the Geant4 Collaboration. It is provided under the terms and *
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// * conditions of the Geant4 Software License, included in the file *
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// * LICENSE and available at http://cern.ch/geant4/license . These *
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// * include a list of copyright holders. *
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// * *
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// * Neither the authors of this software system, nor their employing *
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// * institutes,nor the agencies providing financial support for this *
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// * work make any representation or warranty, express or implied, *
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// * regarding this software system or assume any liability for its *
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// * use. Please see the license in the file LICENSE and URL above *
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// * for the full disclaimer and the limitation of liability. *
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// * *
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// * This code implementation is the result of the scientific and *
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// * technical work of the GEANT4 collaboration. *
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// * By using, copying, modifying or distributing the software (or *
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// * any work based on the software) you agree to acknowledge its *
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// * use in resulting scientific publications, and indicate your *
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// * acceptance of all terms of the Geant4 Software license. *
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// ********************************************************************
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//
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//
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// $Id: $
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//
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// Description:
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// G4BulirschStoer class implementation by Dmitry Sorokin
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// Implementation is based on bulirsch_stoer.hpp from boost
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//
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// The Bulirsch-Stoer is a controlled driver that adjusts both step size
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// and order of the method. The algorithm uses the modified midpoint and
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// a polynomial extrapolation compute the solution.
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// Implementation by Dmitry Sorokin - GSoC 2016
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// Work supported by Google as part of Google Summer of Code 2016.
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// Supervision / code review: John Apostolakis
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//
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///////////////////////////////////////////////////////////////////////////////
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#ifndef G4BULIRSCH_STOER_HH
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#define G4BULIRSCH_STOER_HH
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#include "G4ModifiedMidpoint.hh"
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#include "G4FieldTrack.hh"
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class G4BulirschStoer
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{
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public:
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enum class step_result
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{
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success,
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fail
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};
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G4BulirschStoer( G4EquationOfMotion* equation, G4int nvar,
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G4double eps_rel, G4double max_dt = DBL_MAX);
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inline void set_max_dt(G4double max_dt);
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inline void set_max_relative_error(G4double eps_rel);
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// Stepper method
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//
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step_result try_step(const G4double in[], const G4double dxdt[],
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G4double& t, G4double out[], G4double& dt);
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// Reset the internal state of the stepper
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//
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void reset();
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inline void SetEquationOfMotion(G4EquationOfMotion* equation);
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inline G4EquationOfMotion* GetEquationOfMotion();
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inline G4int GetNumberOfVariables() const;
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private:
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const static G4int m_k_max = 8;
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void extrapolate(size_t k, G4double xest[]);
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G4double calc_h_opt(G4double h, G4double error, size_t k) const;
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G4bool set_k_opt(size_t k, G4double& dt);
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G4bool in_convergence_window(G4int k) const;
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G4bool should_reject(G4double error, G4int k) const;
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// Number of vars to be integrated
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G4int fnvar;
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// Relative tolerance
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G4double m_eps_rel;
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// Modified midpoint algorithm
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G4ModifiedMidpoint m_midpoint;
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G4bool m_last_step_rejected;
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G4bool m_first;
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G4double m_dt_last;
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// G4double m_t_last;
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// Max allowed time step
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G4double m_max_dt;
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G4int m_current_k_opt;
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// G4double m_xnew[G4FieldTrack::ncompSVEC];
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G4double m_err[G4FieldTrack::ncompSVEC];
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// G4double m_dxdt[G4FieldTrack::ncompSVEC];
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// Stores the successive interval counts
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G4int m_interval_sequence[m_k_max+1];
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// Extrapolation coeffs (Neville’s algorithm)
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G4double m_coeff[m_k_max+1][m_k_max];
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// Costs for interval count
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G4int m_cost[m_k_max+1];
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// Sequence of states for extrapolation
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G4double m_table[m_k_max][G4FieldTrack::ncompSVEC];
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// Optimal step size
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G4double h_opt[m_k_max+1];
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// Work per unit step
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G4double work[m_k_max+1];
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};
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#include "G4BulirschStoer.icc"
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#endif
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