Ginkgo Generated from develop branch based on develop. Ginkgo version 1.8.0
A numerical linear algebra library targeting many-core architectures
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cg.hpp
1// SPDX-FileCopyrightText: 2017 - 2024 The Ginkgo authors
2//
3// SPDX-License-Identifier: BSD-3-Clause
4
5#ifndef GKO_PUBLIC_CORE_SOLVER_CG_HPP_
6#define GKO_PUBLIC_CORE_SOLVER_CG_HPP_
7
8
9#include <vector>
10
11
12#include <ginkgo/core/base/array.hpp>
13#include <ginkgo/core/base/exception_helpers.hpp>
14#include <ginkgo/core/base/lin_op.hpp>
15#include <ginkgo/core/base/math.hpp>
16#include <ginkgo/core/base/types.hpp>
17#include <ginkgo/core/log/logger.hpp>
18#include <ginkgo/core/matrix/dense.hpp>
19#include <ginkgo/core/matrix/identity.hpp>
20#include <ginkgo/core/solver/solver_base.hpp>
21#include <ginkgo/core/stop/combined.hpp>
22#include <ginkgo/core/stop/criterion.hpp>
23
24
25namespace gko {
26namespace solver {
27
28
45template <typename ValueType = default_precision>
46class Cg : public EnableLinOp<Cg<ValueType>>,
47 public EnablePreconditionedIterativeSolver<ValueType, Cg<ValueType>>,
48 public Transposable {
49 friend class EnableLinOp<Cg>;
50 friend class EnablePolymorphicObject<Cg, LinOp>;
51
52public:
53 using value_type = ValueType;
55
56 std::unique_ptr<LinOp> transpose() const override;
57
58 std::unique_ptr<LinOp> conj_transpose() const override;
59
65 bool apply_uses_initial_guess() const override { return true; }
66
67 class Factory;
68
72
75
76protected:
77 void apply_impl(const LinOp* b, LinOp* x) const override;
78
79 template <typename VectorType>
80 void apply_dense_impl(const VectorType* b, VectorType* x) const;
81
82 void apply_impl(const LinOp* alpha, const LinOp* b, const LinOp* beta,
83 LinOp* x) const override;
84
85 explicit Cg(std::shared_ptr<const Executor> exec)
86 : EnableLinOp<Cg>(std::move(exec))
87 {}
88
89 explicit Cg(const Factory* factory,
90 std::shared_ptr<const LinOp> system_matrix)
91 : EnableLinOp<Cg>(factory->get_executor(),
92 gko::transpose(system_matrix->get_size())),
93 EnablePreconditionedIterativeSolver<ValueType, Cg<ValueType>>{
94 std::move(system_matrix), factory->get_parameters()},
95 parameters_{factory->get_parameters()}
96 {}
97};
98
99
100template <typename ValueType>
101struct workspace_traits<Cg<ValueType>> {
102 using Solver = Cg<ValueType>;
103 // number of vectors used by this workspace
104 static int num_vectors(const Solver&);
105 // number of arrays used by this workspace
106 static int num_arrays(const Solver&);
107 // array containing the num_vectors names for the workspace vectors
108 static std::vector<std::string> op_names(const Solver&);
109 // array containing the num_arrays names for the workspace vectors
110 static std::vector<std::string> array_names(const Solver&);
111 // array containing all varying scalar vectors (independent of problem size)
112 static std::vector<int> scalars(const Solver&);
113 // array containing all varying vectors (dependent on problem size)
114 static std::vector<int> vectors(const Solver&);
115
116 // residual vector
117 constexpr static int r = 0;
118 // preconditioned residual vector
119 constexpr static int z = 1;
120 // p vector
121 constexpr static int p = 2;
122 // q vector
123 constexpr static int q = 3;
124 // alpha scalar
125 constexpr static int alpha = 4;
126 // beta scalar
127 constexpr static int beta = 5;
128 // previous rho scalar
129 constexpr static int prev_rho = 6;
130 // current rho scalar
131 constexpr static int rho = 7;
132 // constant 1.0 scalar
133 constexpr static int one = 8;
134 // constant -1.0 scalar
135 constexpr static int minus_one = 9;
136
137 // stopping status array
138 constexpr static int stop = 0;
139 // reduction tmp array
140 constexpr static int tmp = 1;
141};
142
143
144} // namespace solver
145} // namespace gko
146
147
148#endif // GKO_PUBLIC_CORE_SOLVER_CG_HPP_
The EnableLinOp mixin can be used to provide sensible default implementations of the majority of the ...
Definition lin_op.hpp:880
This mixin inherits from (a subclass of) PolymorphicObject and provides a base implementation of a ne...
Definition polymorphic_object.hpp:663
Definition lin_op.hpp:118
std::shared_ptr< const Executor > get_executor() const noexcept
Returns the Executor of the object.
Definition polymorphic_object.hpp:235
Linear operators which support transposition should implement the Transposable interface.
Definition lin_op.hpp:434
Definition cg.hpp:73
CG or the conjugate gradient method is an iterative type Krylov subspace method which is suitable for...
Definition cg.hpp:48
std::unique_ptr< LinOp > conj_transpose() const override
Returns a LinOp representing the conjugate transpose of the Transposable object.
std::unique_ptr< LinOp > transpose() const override
Returns a LinOp representing the transpose of the Transposable object.
bool apply_uses_initial_guess() const override
Return true as iterative solvers use the data in x as an initial guess.
Definition cg.hpp:65
A LinOp implementing this interface stores a system matrix and stopping criterion factory.
Definition solver_base.hpp:788
#define GKO_ENABLE_BUILD_METHOD(_factory_name)
Defines a build method for the factory, simplifying its construction by removing the repetitive typin...
Definition abstract_factory.hpp:394
#define GKO_ENABLE_LIN_OP_FACTORY(_lin_op, _parameters_name, _factory_name)
This macro will generate a default implementation of a LinOpFactory for the LinOp subclass it is defi...
Definition lin_op.hpp:1018
The Ginkgo namespace.
Definition abstract_factory.hpp:20
constexpr T one()
Returns the multiplicative identity for T.
Definition math.hpp:775
Traits class providing information on the type and location of workspace vectors inside a solver.
Definition solver_base.hpp:239