BatheTwoStep.h

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/*******************************************************************************
 * Copyright (C) 2017-2025 Theodore Chang
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ******************************************************************************/
#ifndef BATHETWOSTEP_H
#define BATHETWOSTEP_H
 
#include "../Integrator.h"
 
class BatheTwoStep final : public ImplicitIntegrator {
    enum class FLAG {
        TRAP,
        EULER
    };
 
    FLAG step_flag = FLAG::TRAP;
 
    const double GM;
 
    const double Q1, Q2, Q0, Q02 = Q0 / Q2, Q12 = Q1 / Q2;
 
    double P0{0.}, P1{0.}, P2{0.}, P3{0.}, P4{0.}, P5{0.}, P6{0.}, P7{0.}, P8{0.}, P9{0.};
 
protected:
    void update_parameter(double) override;
 
public:
    BatheTwoStep(unsigned, double, double);
 
    [[nodiscard]] bool time_independent_matrix() const override;
 
    void assemble_resistance() override;
    void assemble_matrix() override;
 
    void update_incre_time(double) override;
 
    int update_trial_status(bool) override;
 
    void commit_status() override;
    void clear_status() override;
 
    vec from_incre_velocity(const vec&, const uvec&) override;
    vec from_incre_acceleration(const vec&, const uvec&) override;
    vec from_total_velocity(const vec&, const uvec&) override;
    vec from_total_acceleration(const vec&, const uvec&) override;
 
    void print() override;
};
 
#endif