gmres.hpp

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#ifndef GKO_CORE_SOLVER_GMRES_HPP_
#define GKO_CORE_SOLVER_GMRES_HPP_


#include <vector>


#include <ginkgo/core/base/array.hpp>
#include <ginkgo/core/base/lin_op.hpp>
#include <ginkgo/core/base/math.hpp>
#include <ginkgo/core/base/types.hpp>
#include <ginkgo/core/log/logger.hpp>
#include <ginkgo/core/matrix/identity.hpp>
#include <ginkgo/core/stop/combined.hpp>
#include <ginkgo/core/stop/criterion.hpp>


namespace gko {
namespace solver {


constexpr size_type default_krylov_dim = 100u;


template <typename ValueType = default_precision>
class Gmres : public EnableLinOp<Gmres<ValueType>>, public Preconditionable {
    friend class EnableLinOp<Gmres>;
    friend class EnablePolymorphicObject<Gmres, LinOp>;

public:
    using value_type = ValueType;

    std::shared_ptr<const LinOp> get_system_matrix() const
    {
        return system_matrix_;
    }

    std::shared_ptr<const LinOp> get_preconditioner() const override
    {
        return preconditioner_;
    }

    size_type get_krylov_dim() const { return krylov_dim_; }

    GKO_CREATE_FACTORY_PARAMETERS(parameters, Factory)
    {
        std::vector<std::shared_ptr<const stop::CriterionFactory>>
            GKO_FACTORY_PARAMETER(criteria, nullptr);

        std::shared_ptr<const LinOpFactory> GKO_FACTORY_PARAMETER(
            preconditioner, nullptr);

        size_type GKO_FACTORY_PARAMETER(krylov_dim, 0u);
    };
    GKO_ENABLE_LIN_OP_FACTORY(Gmres, parameters, Factory);
    GKO_ENABLE_BUILD_METHOD(Factory);

protected:
    void apply_impl(const LinOp *b, LinOp *x) const override;

    void apply_impl(const LinOp *alpha, const LinOp *b, const LinOp *beta,
                    LinOp *x) const override;

    explicit Gmres(std::shared_ptr<const Executor> exec)
        : EnableLinOp<Gmres>(std::move(exec))
    {}

    explicit Gmres(const Factory *factory,
                   std::shared_ptr<const LinOp> system_matrix)
        : EnableLinOp<Gmres>(factory->get_executor(),
                             transpose(system_matrix->get_size())),
          parameters_{factory->get_parameters()},
          system_matrix_{std::move(system_matrix)}
    {
        if (parameters_.preconditioner) {
            preconditioner_ =
                parameters_.preconditioner->generate(system_matrix_);
        } else {
            preconditioner_ = matrix::Identity<ValueType>::create(
                this->get_executor(), this->get_size()[0]);
        }
        if (parameters_.krylov_dim) {
            krylov_dim_ = parameters_.krylov_dim;
        } else {
            krylov_dim_ = default_krylov_dim;
        }
        stop_criterion_factory_ =
            stop::combine(std::move(parameters_.criteria));
    }

private:
    std::shared_ptr<const LinOp> system_matrix_{};
    std::shared_ptr<const LinOp> preconditioner_{};
    std::shared_ptr<const stop::CriterionFactory> stop_criterion_factory_{};
    size_type krylov_dim_;
};


}  // namespace solver
}  // namespace gko


#endif  // GKO_CORE_SOLVER_GMRES_HPP