residual_norm_reduction.hpp

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#ifndef GKO_CORE_STOP_RESIDUAL_NORM_REDUCTION_HPP_
#define GKO_CORE_STOP_RESIDUAL_NORM_REDUCTION_HPP_


#include <ginkgo/core/base/array.hpp>
#include <ginkgo/core/base/utils.hpp>
#include <ginkgo/core/matrix/dense.hpp>
#include <ginkgo/core/stop/criterion.hpp>


#include <type_traits>


namespace gko {
namespace stop {

template <typename ValueType = default_precision>
class ResidualNormReduction
    : public EnablePolymorphicObject<ResidualNormReduction<ValueType>,
                                     Criterion> {
    friend class EnablePolymorphicObject<ResidualNormReduction<ValueType>,
                                         Criterion>;

public:
    using Vector = matrix::Dense<ValueType>;

    GKO_CREATE_FACTORY_PARAMETERS(parameters, Factory)
    {
        remove_complex<ValueType> GKO_FACTORY_PARAMETER(reduction_factor,
                                                        1e-15);
    };
    GKO_ENABLE_CRITERION_FACTORY(ResidualNormReduction<ValueType>, parameters,
                                 Factory);
    GKO_ENABLE_BUILD_METHOD(Factory);

protected:
    bool check_impl(uint8 stoppingId, bool setFinalized,
                    Array<stopping_status> *stop_status, bool *one_changed,
                    const Criterion::Updater &) override;

    explicit ResidualNormReduction(std::shared_ptr<const gko::Executor> exec)
        : EnablePolymorphicObject<ResidualNormReduction, Criterion>(exec),
          device_storage_{exec, 2}
    {}

    explicit ResidualNormReduction(const Factory *factory,
                                   const CriterionArgs &args)
        : EnablePolymorphicObject<ResidualNormReduction, Criterion>(
              factory->get_executor()),
          parameters_{factory->get_parameters()},
          device_storage_{factory->get_executor(), 2}
    {
        if (args.initial_residual == nullptr) {
            GKO_NOT_SUPPORTED(nullptr);
        }

        auto exec = factory->get_executor();

        auto dense_r = as<Vector>(args.initial_residual);
        starting_tau_ = Vector::create(
            exec, dim<2>{1, args.initial_residual->get_size()[1]});
        u_dense_tau_ = Vector::create_with_config_of(starting_tau_.get());
        dense_r->compute_norm2(starting_tau_.get());
    }

private:
    std::unique_ptr<Vector> starting_tau_{};
    std::unique_ptr<Vector> u_dense_tau_{};
    /* Contains device side: all_converged and one_changed booleans */
    Array<bool> device_storage_;
};


}  // namespace stop
}  // namespace gko


#endif  // GKO_CORE_STOP_RESIDUAL_NORM_REDUCTION_HPP_