triangular.hpp

// SPDX-FileCopyrightText: 2017 - 2025 The Ginkgo authors
//
// SPDX-License-Identifier: BSD-3-Clause
 
#ifndef GKO_PUBLIC_CORE_SOLVER_TRIANGULAR_HPP_
#define GKO_PUBLIC_CORE_SOLVER_TRIANGULAR_HPP_
 
 
#include <memory>
#include <utility>
 
#include <ginkgo/core/base/abstract_factory.hpp>
#include <ginkgo/core/base/array.hpp>
#include <ginkgo/core/base/dim.hpp>
#include <ginkgo/core/base/exception_helpers.hpp>
#include <ginkgo/core/base/lin_op.hpp>
#include <ginkgo/core/base/polymorphic_object.hpp>
#include <ginkgo/core/base/types.hpp>
#include <ginkgo/core/base/utils.hpp>
#include <ginkgo/core/config/config.hpp>
#include <ginkgo/core/config/registry.hpp>
#include <ginkgo/core/log/logger.hpp>
#include <ginkgo/core/matrix/csr.hpp>
#include <ginkgo/core/matrix/identity.hpp>
#include <ginkgo/core/solver/solver_base.hpp>
 
 
namespace gko {
namespace solver {
 
 
struct SolveStruct;
 

enum class trisolve_algorithm { sparselib, syncfree };
 
 
template <typename ValueType, typename IndexType>
class UpperTrs;
 

template <typename ValueType = default_precision, typename IndexType = int32>
class LowerTrs : public EnableLinOp<LowerTrs<ValueType, IndexType>>,
                 public EnableSolverBase<LowerTrs<ValueType, IndexType>,
                                         matrix::Csr<ValueType, IndexType>>,
                 public Transposable {
    friend class EnableLinOp<LowerTrs>;
    friend class EnablePolymorphicObject<LowerTrs, LinOp>;
    friend class UpperTrs<ValueType, IndexType>;
    GKO_ASSERT_SUPPORTED_VALUE_AND_INDEX_TYPE;
 
public:
    using value_type = ValueType;
    using index_type = IndexType;
    using transposed_type = UpperTrs<ValueType, IndexType>;
 
    std::unique_ptr<LinOp> transpose() const override;
 
    std::unique_ptr<LinOp> conj_transpose() const override;
 
    GKO_CREATE_FACTORY_PARAMETERS(parameters, Factory)
    {
        gko::size_type GKO_FACTORY_PARAMETER_SCALAR(num_rhs, 1u);

        bool GKO_FACTORY_PARAMETER_SCALAR(unit_diagonal, false);

        trisolve_algorithm GKO_FACTORY_PARAMETER_SCALAR(
            algorithm, trisolve_algorithm::sparselib);
    };
    GKO_ENABLE_LIN_OP_FACTORY(LowerTrs, 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>());

    LowerTrs(const LowerTrs&);

    LowerTrs(LowerTrs&&);

    LowerTrs& operator=(const LowerTrs&);

    LowerTrs& operator=(LowerTrs&&);
 
protected:
    using CsrMatrix = matrix::Csr<ValueType, IndexType>;
 
    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;

    void generate();
 
    explicit LowerTrs(std::shared_ptr<const Executor> exec)
        : EnableLinOp<LowerTrs>(std::move(exec))
    {}
 
    explicit LowerTrs(const Factory* factory,
                      std::shared_ptr<const LinOp> system_matrix)
        : EnableLinOp<LowerTrs>(factory->get_executor(),
                                gko::transpose(system_matrix->get_size())),
          EnableSolverBase<LowerTrs<ValueType, IndexType>, CsrMatrix>{
              copy_and_convert_to<CsrMatrix>(factory->get_executor(),
                                             system_matrix)},
          parameters_{factory->get_parameters()}
    {
        this->generate();
    }
 
private:
    std::shared_ptr<solver::SolveStruct> solve_struct_;
};
 
 
template <typename ValueType, typename IndexType>
struct workspace_traits<LowerTrs<ValueType, IndexType>> {
    using Solver = LowerTrs<ValueType, IndexType>;
    // number of vectors used by this workspace
    static int num_vectors(const Solver&);
    // number of arrays used by this workspace
    static int num_arrays(const Solver&);
    // array containing the num_vectors names for the workspace vectors
    static std::vector<std::string> op_names(const Solver&);
    // array containing the num_arrays names for the workspace vectors
    static std::vector<std::string> array_names(const Solver&);
    // array containing all varying scalar vectors (independent of problem size)
    static std::vector<int> scalars(const Solver&);
    // array containing all varying vectors (dependent on problem size)
    static std::vector<int> vectors(const Solver&);
 
    // transposed input vector
    constexpr static int transposed_b = 0;
    // transposed output vector
    constexpr static int transposed_x = 1;
};
 

template <typename ValueType = default_precision, typename IndexType = int32>
class UpperTrs : public EnableLinOp<UpperTrs<ValueType, IndexType>>,
                 public EnableSolverBase<UpperTrs<ValueType, IndexType>,
                                         matrix::Csr<ValueType, IndexType>>,
                 public Transposable {
    friend class EnableLinOp<UpperTrs>;
    friend class EnablePolymorphicObject<UpperTrs, LinOp>;
    friend class LowerTrs<ValueType, IndexType>;
    GKO_ASSERT_SUPPORTED_VALUE_AND_INDEX_TYPE;
 
public:
    using value_type = ValueType;
    using index_type = IndexType;
    using transposed_type = LowerTrs<ValueType, IndexType>;
 
    std::unique_ptr<LinOp> transpose() const override;
 
    std::unique_ptr<LinOp> conj_transpose() const override;
 
    GKO_CREATE_FACTORY_PARAMETERS(parameters, Factory)
    {
        gko::size_type GKO_FACTORY_PARAMETER_SCALAR(num_rhs, 1u);

        bool GKO_FACTORY_PARAMETER_SCALAR(unit_diagonal, false);

        trisolve_algorithm GKO_FACTORY_PARAMETER_SCALAR(
            algorithm, trisolve_algorithm::sparselib);
    };
    GKO_ENABLE_LIN_OP_FACTORY(UpperTrs, 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>());

    UpperTrs(const UpperTrs&);

    UpperTrs(UpperTrs&&);

    UpperTrs& operator=(const UpperTrs&);

    UpperTrs& operator=(UpperTrs&&);
 
protected:
    using CsrMatrix = matrix::Csr<ValueType, IndexType>;
 
    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;

    void generate();
 
    explicit UpperTrs(std::shared_ptr<const Executor> exec)
        : EnableLinOp<UpperTrs>(std::move(exec))
    {}
 
    explicit UpperTrs(const Factory* factory,
                      std::shared_ptr<const LinOp> system_matrix)
        : EnableLinOp<UpperTrs>(factory->get_executor(),
                                gko::transpose(system_matrix->get_size())),
          EnableSolverBase<UpperTrs<ValueType, IndexType>, CsrMatrix>{
              copy_and_convert_to<CsrMatrix>(factory->get_executor(),
                                             system_matrix)},
          parameters_{factory->get_parameters()}
    {
        this->generate();
    }
 
private:
    std::shared_ptr<solver::SolveStruct> solve_struct_;
};
 
 
template <typename ValueType, typename IndexType>
struct workspace_traits<UpperTrs<ValueType, IndexType>> {
    using Solver = UpperTrs<ValueType, IndexType>;
    // number of vectors used by this workspace
    static int num_vectors(const Solver&);
    // number of arrays used by this workspace
    static int num_arrays(const Solver&);
    // array containing the num_vectors names for the workspace vectors
    static std::vector<std::string> op_names(const Solver&);
    // array containing the num_arrays names for the workspace vectors
    static std::vector<std::string> array_names(const Solver&);
    // array containing all varying scalar vectors (independent of problem size)
    static std::vector<int> scalars(const Solver&);
    // array containing all varying vectors (dependent on problem size)
    static std::vector<int> vectors(const Solver&);
 
    // transposed input vector
    constexpr static int transposed_b = 0;
    // transposed output vector
    constexpr static int transposed_x = 1;
};
 
 
}  // namespace solver
}  // namespace gko
 
 
#endif  // GKO_PUBLIC_CORE_SOLVER_TRIANGULAR_HPP_