ilu.hpp

// SPDX-FileCopyrightText: 2017 - 2026 The Ginkgo authors
//
// SPDX-License-Identifier: BSD-3-Clause
 
#ifndef GKO_PUBLIC_CORE_PRECONDITIONER_ILU_HPP_
#define GKO_PUBLIC_CORE_PRECONDITIONER_ILU_HPP_
 
 
#include <memory>
#include <type_traits>
 
#include <ginkgo/core/base/abstract_factory.hpp>
#include <ginkgo/core/base/composition.hpp>
#include <ginkgo/core/base/exception.hpp>
#include <ginkgo/core/base/exception_helpers.hpp>
#include <ginkgo/core/base/lin_op.hpp>
#include <ginkgo/core/base/precision_dispatch.hpp>
#include <ginkgo/core/base/type_traits.hpp>
#include <ginkgo/core/config/config.hpp>
#include <ginkgo/core/config/registry.hpp>
#include <ginkgo/core/factorization/par_ilu.hpp>
#include <ginkgo/core/matrix/dense.hpp>
#include <ginkgo/core/solver/solver_traits.hpp>
#include <ginkgo/core/solver/triangular.hpp>
#include <ginkgo/core/stop/combined.hpp>
#include <ginkgo/core/stop/iteration.hpp>
#include <ginkgo/core/stop/residual_norm.hpp>
 
 
namespace gko {
namespace preconditioner {
 
 
template <typename ValueType = default_precision, bool ReverseApply = false,
          typename IndexType = int32>
class Ilu : public LinOp, public Transposable {
public:
    using value_type = ValueType;
    static constexpr bool performs_reverse_apply = ReverseApply;
    using index_type = IndexType;
    using transposed_type = Ilu;
 
    class Factory;
 
    struct parameters_type
        : public enable_parameters_type<parameters_type, Factory> {
        std::shared_ptr<const LinOpFactory> l_solver_factory{};
 
        std::shared_ptr<const LinOpFactory> u_solver_factory{};
 
        std::shared_ptr<const LinOpFactory> factorization_factory{};
 
        parameters_type& with_l_solver(
            deferred_factory_parameter<const LinOpFactory> solver);
 
        parameters_type& with_u_solver(
            deferred_factory_parameter<const LinOpFactory> solver)
        {
            this->u_solver_generator = std::move(solver);
            this->deferred_factories["u_solver"] = [](const auto& exec,
                                                      auto& params) {
                if (!params.u_solver_generator.is_empty()) {
                    params.u_solver_factory =
                        params.u_solver_generator.on(exec);
                }
            };
            return *this;
        }
 
        parameters_type& with_factorization(
            deferred_factory_parameter<const LinOpFactory> factorization)
        {
            this->factorization_generator = std::move(factorization);
            this->deferred_factories["factorization"] = [](const auto& exec,
                                                           auto& params) {
                if (!params.factorization_generator.is_empty()) {
                    params.factorization_factory =
                        params.factorization_generator.on(exec);
                }
            };
            return *this;
        }
 
    private:
        deferred_factory_parameter<const LinOpFactory> l_solver_generator;
        deferred_factory_parameter<const LinOpFactory> u_solver_generator;
        deferred_factory_parameter<const LinOpFactory> factorization_generator;
    };
 
    GKO_ENABLE_LIN_OP_FACTORY(Ilu, 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<value_type, index_type>());
 
    std::shared_ptr<const LinOp> get_l_solver() const { return l_solver_; }
 
    std::shared_ptr<const LinOp> get_u_solver() const { return u_solver_; }
 
    std::unique_ptr<LinOp> transpose() const override;
 
    std::unique_ptr<LinOp> conj_transpose() const override;
 
    Ilu& operator=(const Ilu& other);
 
    Ilu& operator=(Ilu&& other);
 
    Ilu(const Ilu& other);
 
    Ilu(Ilu&& other);
 
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 Ilu(std::shared_ptr<const Executor> exec);
 
    explicit Ilu(const Factory* factory, std::shared_ptr<const LinOp> lin_op);
 
    void set_cache_to(const LinOp* b) const;
 
private:
    std::shared_ptr<const LinOp> l_solver_{};
    std::shared_ptr<const LinOp> u_solver_{};
    mutable struct cache_struct {
        cache_struct() = default;
        ~cache_struct() = default;
        cache_struct(const cache_struct&) {}
        cache_struct(cache_struct&&) {}
        cache_struct& operator=(const cache_struct&) { return *this; }
        cache_struct& operator=(cache_struct&&) { return *this; }
        std::unique_ptr<LinOp> intermediate{};
    } cache_;
};
 
 
}  // namespace preconditioner
}  // namespace gko
 
 
#endif  // GKO_PUBLIC_CORE_PRECONDITIONER_ILU_HPP_