MG.h

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/*************************************************************************
> File Name: MultiGrid.h
> Project Name: CubbyFlow
> Author: Chan-Ho Chris Ohk
> Purpose: Multi-grid wrapper functions for CubbyFlow.
> Created Time: 2017/09/26
> Copyright (c) 2018, Chan-Ho Chris Ohk
*************************************************************************/
#ifndef CUBBYFLOW_MULTI_GRID_H
#define CUBBYFLOW_MULTI_GRID_H

#include <functional>

namespace CubbyFlow
{
    template <typename BlasType>
    struct MGMatrix
    {
        std::vector<typename BlasType::MatrixType> levels;
        const typename BlasType::MatrixType& operator[](size_t i) const;
        typename BlasType::MatrixType& operator[](size_t i);
        const typename BlasType::MatrixType& Finest() const;
        typename BlasType::MatrixType& Finest();
    };

    template <typename BlasType>
    struct MGVector
    {
        std::vector<typename BlasType::VectorType> levels;
        const typename BlasType::VectorType& operator[](size_t i) const;
        typename BlasType::VectorType& operator[](size_t i);
        const typename BlasType::VectorType& Finest() const;
        typename BlasType::VectorType& Finest();
    };

    template <typename BlasType>
    using MGRelaxFunc = std::function<void(
        const typename BlasType::MatrixType& A,
        const typename BlasType::VectorType& b, unsigned int numberOfIterations,
        double maxTolerance, typename BlasType::VectorType* x,
        typename BlasType::VectorType* buffer)>;

    template <typename BlasType>
    using MGRestrictFunc = std::function<void(
        const typename BlasType::VectorType& finer,
        typename BlasType::VectorType* coarser)>;

    template <typename BlasType>
    using MGCorrectFunc = std::function<void(
        const typename BlasType::VectorType& coarser,
        typename BlasType::VectorType* finer)>;

    template <typename BlasType>
    struct MGParameters
    {
        size_t maxNumberOfLevels = 1;

        unsigned int numberOfRestrictionIter = 5;

        unsigned int numberOfCorrectionIter = 5;

        unsigned int numberOfCoarsestIter = 20;

        unsigned int numberOfFinalIter = 20;

        MGRelaxFunc<BlasType> relaxFunc;

        MGRestrictFunc<BlasType> restrictFunc;

        MGCorrectFunc<BlasType> correctFunc;

        double maxTolerance = 1e-9;
    };

    struct MGResult
    {
        double lastResidualNorm;
    };

    template <typename BlasType>
    MGResult MGCycle(
        const MGMatrix<BlasType>& A, MGParameters<BlasType> params,
        MGVector<BlasType>* x, MGVector<BlasType>* b,
        MGVector<BlasType>* buffer);
}

#include <Core/Utils/MG-Impl.h>

#endif