par_ilut.hpp

// SPDX-FileCopyrightText: 2017 - 2025 The Ginkgo authors
//
// SPDX-License-Identifier: BSD-3-Clause
 
#ifndef GKO_PUBLIC_CORE_FACTORIZATION_PAR_ILUT_HPP_
#define GKO_PUBLIC_CORE_FACTORIZATION_PAR_ILUT_HPP_
 
 
#include <memory>
 
#include <ginkgo/core/base/composition.hpp>
#include <ginkgo/core/base/lin_op.hpp>
#include <ginkgo/core/base/types.hpp>
#include <ginkgo/core/config/config.hpp>
#include <ginkgo/core/config/registry.hpp>
#include <ginkgo/core/matrix/csr.hpp>
 
 
namespace gko {
namespace factorization {
 

template <typename ValueType = default_precision, typename IndexType = int32>
class ParIlut : public Composition<ValueType> {
    GKO_ASSERT_SUPPORTED_VALUE_AND_INDEX_TYPE;
 
public:
    using value_type = ValueType;
    using index_type = IndexType;
    using matrix_type = matrix::Csr<ValueType, IndexType>;
    using l_matrix_type = matrix_type;
    using u_matrix_type = matrix_type;
 
    std::shared_ptr<const matrix_type> get_l_factor() const
    {
        // Can be `static_cast` since the type is guaranteed in this class
        return std::static_pointer_cast<const matrix_type>(
            this->get_operators()[0]);
    }
 
    std::shared_ptr<const matrix_type> get_u_factor() const
    {
        // Can be `static_cast` since the type is guaranteed in this class
        return std::static_pointer_cast<const matrix_type>(
            this->get_operators()[1]);
    }
 
    // Remove the possibility of calling `create`, which was enabled by
    // `Composition`
    template <typename... Args>
    static std::unique_ptr<Composition<ValueType>> create(Args&&... args) =
        delete;
 
    GKO_CREATE_FACTORY_PARAMETERS(parameters, Factory)
    {
        size_type GKO_FACTORY_PARAMETER_SCALAR(iterations, 5);

        bool GKO_FACTORY_PARAMETER_SCALAR(skip_sorting, false);

        bool GKO_FACTORY_PARAMETER_SCALAR(approximate_select, true);

        bool GKO_FACTORY_PARAMETER_SCALAR(deterministic_sample, false);

        double GKO_FACTORY_PARAMETER_SCALAR(fill_in_limit, 2.0);

        std::shared_ptr<typename matrix_type::strategy_type>
            GKO_FACTORY_PARAMETER_SCALAR(l_strategy, nullptr);

        std::shared_ptr<typename matrix_type::strategy_type>
            GKO_FACTORY_PARAMETER_SCALAR(u_strategy, nullptr);
    };
    GKO_ENABLE_LIN_OP_FACTORY(ParIlut, parameters, Factory);
    GKO_ENABLE_BUILD_METHOD(Factory);

    static parameters_type parse(
        const config::pnode& config, const config::registry& context,
        const config::type_descriptor& td_for_child =
            config::make_type_descriptor<ValueType, IndexType>());
 
protected:
    explicit ParIlut(const Factory* factory,
                     std::shared_ptr<const LinOp> system_matrix)
        : Composition<ValueType>(factory->get_executor()),
          parameters_{factory->get_parameters()}
    {
        if (parameters_.l_strategy == nullptr) {
            parameters_.l_strategy =
                std::make_shared<typename matrix_type::classical>();
        }
        if (parameters_.u_strategy == nullptr) {
            parameters_.u_strategy =
                std::make_shared<typename matrix_type::classical>();
        }
        generate_l_u(std::move(system_matrix))->move_to(this);
    }

    std::unique_ptr<Composition<ValueType>> generate_l_u(
        const std::shared_ptr<const LinOp>& system_matrix) const;
};
 
 
}  // namespace factorization
}  // namespace gko
 
 
#endif  // GKO_PUBLIC_CORE_FACTORIZATION_PAR_ILUT_HPP_