broyden.hpp

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/*
 * This file is part of PLaSK (https://plask.app) by Photonics Group at TUL
 * Copyright (c) 2022 Lodz University of Technology
 *
 * 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, version 3.
 *
 * 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.
 */
#ifndef PLASK__OPTICAL_SLAB_BROYDEN_H
#define PLASK__OPTICAL_SLAB_BROYDEN_H
 
#include "rootdigger.hpp"
#include "solver.hpp"
 
namespace plask { namespace optical { namespace modal {
 
class RootBroyden: public RootDigger {
 
    // Parameters for Broyden algorithm
    static constexpr double EPS = 1e6 * SMALL; 
 
    // Return Jacobian of F(x)
    void fdjac(dcomplex x, dcomplex F, dcomplex& Jr, dcomplex& Ji);
 
    // Search for the new point x along direction p for which f decreased sufficiently
    bool lnsearch(dcomplex& x, dcomplex& F, dcomplex g, dcomplex p, double stpmax);
 
    // Search for the root of char_val using globally convergent Broyden method
    dcomplex Broyden(dcomplex x);
 
    // Write log message
    template <typename... Args>
    void writelog(LogLevel level, const std::string& msg, Args&&... args) const {
        std::string prefix = solver.getId(); prefix += ": "; prefix += log_value.chartName(); prefix += ": ";
        plask::writelog(level, prefix + msg, std::forward<Args>(args)...);
    }
 
  public:
 
    // Constructor
    RootBroyden(ModalBase& solver, const function_type& val_fun, const Params& pars, const char* name):
        RootDigger(solver, val_fun, pars, name) {}
 
    dcomplex find(dcomplex start) override;
};
 
}}} // namespace plask::optical::modal
#endif // PLASK__OPTICAL_SLAB_BROYDEN_H