FDMMGPCGSolver2.hpp

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// This code is based on Jet framework.
// Copyright (c) 2018 Doyub Kim
// CubbyFlow is voxel-based fluid simulation engine for computer games.
// Copyright (c) 2020 CubbyFlow Team
// Core Part: Chris Ohk, Junwoo Hwang, Jihong Sin, Seungwoo Yoo
// AI Part: Dongheon Cho, Minseo Kim
// We are making my contributions/submissions to this project solely in our
// personal capacity and are not conveying any rights to any intellectual
// property of any third parties.

#ifndef CUBBYFLOW_FDM_MGPCG_SOLVER2_HPP
#define CUBBYFLOW_FDM_MGPCG_SOLVER2_HPP

#include <Core/Solver/FDM/FDMMGSolver2.hpp>

namespace CubbyFlow
{
class FDMMGPCGSolver2 final : public FDMMGSolver2
{
 public:
    FDMMGPCGSolver2(unsigned int numberOfCGIter, size_t maxNumberOfLevels,
                    unsigned int numberOfRestrictionIter = 5,
                    unsigned int numberOfCorrectionIter = 5,
                    unsigned int numberOfCoarsestIter = 20,
                    unsigned int numberOfFinalIter = 20,
                    double maxTolerance = 1e-9, double sorFactor = 1.5,
                    bool useRedBlackOrdering = false);

    bool Solve(FDMMGLinearSystem2* system) override;

    [[nodiscard]] unsigned int GetMaxNumberOfIterations() const;

    [[nodiscard]] unsigned int GetLastNumberOfIterations() const;

    [[nodiscard]] double GetTolerance() const;

    [[nodiscard]] double GetLastResidual() const;

 private:
    struct Preconditioner final
    {
        void Build(FDMMGLinearSystem2* system, MGParameters<FDMBLAS2> mgParams);

        void Solve(const FDMVector2& b, FDMVector2* x) const;

        FDMMGLinearSystem2* system = nullptr;
        MGParameters<FDMBLAS2> mgParams;
    };

    unsigned int m_maxNumberOfIterations;
    unsigned int m_lastNumberOfIterations;
    double m_tolerance;
    double m_lastResidualNorm;

    FDMVector2 m_r;
    FDMVector2 m_d;
    FDMVector2 m_q;
    FDMVector2 m_s;
    Preconditioner m_precond;
};

using FDMMGPCGSolver2Ptr = std::shared_ptr<FDMMGPCGSolver2>;
}  // namespace CubbyFlow

#endif