gmres_base.h

//
// Created by RainSure on 2024/2/13.
//
 
#ifndef RSMESH_GMRES_BASE_H
#define RSMESH_GMRES_BASE_H
 
#include "Eigen/Core"
#include "linear_operator.h"
#include "types.h"
#include <vector>
 
namespace rsmesh::krylov {
    class gmres_base {
    public:
        static bool print_progress;
 
        virtual ~gmres_base() = default;
 
        gmres_base(const gmres_base &) = delete;
 
        gmres_base(gmres_base &&) = delete;
 
        gmres_base &operator=(const gmres_base &) = delete;
 
        gmres_base &operator=(gmres_base &&) = delete;
 
        [[nodiscard]] double absolute_residual() const;
 
        [[nodiscard]] bool converged() const;
 
        virtual void iterate_process() = 0;
 
        [[nodiscard]] index_t iteration_count() const;
 
        [[nodiscard]] index_t max_iterations() const;
 
        [[nodiscard]] double relative_residual() const;
 
        virtual void set_left_preconditioner(const linear_operator &left_preconditioner);
 
        void set_initial_solution(const valuesd &x0);
 
        virtual void set_right_preconditioner(const linear_operator &right_preconditioner);
 
        virtual void setup();
 
        virtual valuesd solution_vector() const;
 
        // tolerance: Tolerance of the relative residual (stopping criterion).
        void solve(double tolerance);
 
    protected:
        gmres_base(const linear_operator &op, const valuesd &rhs, index_t max_iter);
 
        virtual void add_preconditioned_krylov_basis(const valuesd & /*z*/) {}
 
        [[nodiscard]] valuesd left_preconditioned(const valuesd &x) const;
 
        [[nodiscard]] valuesd right_preconditioned(const valuesd &x) const;
 
        const linear_operator &op_;
 
        // Dimension.
        const index_t m_;
 
        // Maximum # of iteration.
        const index_t max_iter_;
 
        // Initial solution.
        valuesd x0_;
 
        // Left preconditioner.
        const linear_operator *left_pc_{};
 
        // Right preconditioner.
        const linear_operator *right_pc_{};
 
        // Current # of iteration.
        index_t iter_{};
 
        // Constant (right-hand side) vector.
        const valuesd rhs_;
 
        // L2 norm of rhs.
        double rhs_norm_;
 
        // Orthonormal basis vectors for the Krylov subspace.
        std::vector<valuesd> vs_;
 
        // Upper triangular matrix of QR decomposition.
        Eigen::MatrixXd r_;
 
        // Cosines for the Givens rotations.
        valuesd c_;
 
        // Sines for the Givens rotations.
        valuesd s_;
 
        // Sequence of residuals.
        valuesd g_;
 
        bool converged_{};
    };
} // namespace rsmesh::krylov
 
#endif //RSMESH_GMRES_BASE_H