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Ginkgo
Generated from pipelines/238965899 branch based on develop. Ginkgo version 1.3.0
A numerical linear algebra library targeting many-core architectures
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A module dedicated to the implementation and usage of the Linear operators in Ginkgo. More...
Modules | |
Factorizations | |
A module dedicated to the implementation and usage of the Factorizations in Ginkgo. | |
SpMV employing different Matrix formats | |
A module dedicated to the implementation and usage of the various Matrix Formats in Ginkgo. | |
Preconditioners | |
A module dedicated to the implementation and usage of the Preconditioners in Ginkgo. | |
Solvers | |
A module dedicated to the implementation and usage of the Solvers in Ginkgo. | |
Classes | |
class | gko::Combination< ValueType > |
The Combination class can be used to construct a linear combination of multiple linear operators c1 * op1 + c2 * op2 + ... More... | |
class | gko::Composition< ValueType > |
The Composition class can be used to compose linear operators op1, op2, ..., opn and obtain the operator op1 * op2 * ... More... | |
class | gko::LinOpFactory |
A LinOpFactory represents a higher order mapping which transforms one linear operator into another. More... | |
class | gko::ReadableFromMatrixData< ValueType, IndexType > |
A LinOp implementing this interface can read its data from a matrix_data structure. More... | |
class | gko::WritableToMatrixData< ValueType, IndexType > |
A LinOp implementing this interface can write its data to a matrix_data structure. More... | |
class | gko::Preconditionable |
A LinOp implementing this interface can be preconditioned. More... | |
class | gko::DiagonalExtractable< ValueType > |
The diagonal of a LinOp implementing this interface can be extracted. More... | |
class | gko::EnableAbsoluteComputation< AbsoluteLinOp > |
The EnableAbsoluteComputation mixin provides the default implementations of compute_absolute_linop and the absolute interface. More... | |
class | gko::EnableLinOp< ConcreteLinOp, PolymorphicBase > |
The EnableLinOp mixin can be used to provide sensible default implementations of the majority of the LinOp and PolymorphicObject interface. More... | |
class | gko::Perturbation< ValueType > |
The Perturbation class can be used to construct a LinOp to represent the operation (identity + scalar * basis * projector) . More... | |
class | gko::factorization::Ilu< ValueType, IndexType > |
Represents an incomplete LU factorization – ILU(0) – of a sparse matrix. More... | |
class | gko::factorization::ParIct< ValueType, IndexType > |
ParICT is an incomplete threshold-based Cholesky factorization which is computed in parallel. More... | |
class | gko::factorization::ParIlu< ValueType, IndexType > |
ParILU is an incomplete LU factorization which is computed in parallel. More... | |
class | gko::factorization::ParIlut< ValueType, IndexType > |
ParILUT is an incomplete threshold-based LU factorization which is computed in parallel. More... | |
class | gko::matrix::Coo< ValueType, IndexType > |
COO stores a matrix in the coordinate matrix format. More... | |
class | gko::matrix::Csr< ValueType, IndexType > |
CSR is a matrix format which stores only the nonzero coefficients by compressing each row of the matrix (compressed sparse row format). More... | |
class | gko::matrix::Dense< ValueType > |
Dense is a matrix format which explicitly stores all values of the matrix. More... | |
class | gko::matrix::Diagonal< ValueType > |
This class is a utility which efficiently implements the diagonal matrix (a linear operator which scales a vector row wise). More... | |
class | gko::matrix::Ell< ValueType, IndexType > |
ELL is a matrix format where stride with explicit zeros is used such that all rows have the same number of stored elements. More... | |
class | gko::matrix::Hybrid< ValueType, IndexType > |
HYBRID is a matrix format which splits the matrix into ELLPACK and COO format. More... | |
class | gko::matrix::Identity< ValueType > |
This class is a utility which efficiently implements the identity matrix (a linear operator which maps each vector to itself). More... | |
class | gko::matrix::IdentityFactory< ValueType > |
This factory is a utility which can be used to generate Identity operators. More... | |
class | gko::matrix::Permutation< IndexType > |
Permutation is a matrix "format" which stores the row and column permutation arrays which can be used for re-ordering the rows and columns a matrix. More... | |
class | gko::matrix::Sellp< ValueType, IndexType > |
SELL-P is a matrix format similar to ELL format. More... | |
class | gko::matrix::SparsityCsr< ValueType, IndexType > |
SparsityCsr is a matrix format which stores only the sparsity pattern of a sparse matrix by compressing each row of the matrix (compressed sparse row format). More... | |
class | gko::preconditioner::Ilu< LSolverType, USolverType, ReverseApply, IndexType > |
The Incomplete LU (ILU) preconditioner solves the equation ![]() | |
class | gko::preconditioner::Isai< IsaiType, ValueType, IndexType > |
The Incomplete Sparse Approximate Inverse (ISAI) Preconditioner generates an approximate inverse matrix for a given lower triangular matrix L or upper triangular matrix U. More... | |
class | gko::preconditioner::Jacobi< ValueType, IndexType > |
A block-Jacobi preconditioner is a block-diagonal linear operator, obtained by inverting the diagonal blocks of the source operator. More... | |
class | gko::solver::Bicg< ValueType > |
BICG or the Biconjugate gradient method is a Krylov subspace solver. More... | |
class | gko::solver::Bicgstab< ValueType > |
BiCGSTAB or the Bi-Conjugate Gradient-Stabilized is a Krylov subspace solver. More... | |
class | gko::solver::Cg< ValueType > |
CG or the conjugate gradient method is an iterative type Krylov subspace method which is suitable for symmetric positive definite methods. More... | |
class | gko::solver::Cgs< ValueType > |
CGS or the conjugate gradient square method is an iterative type Krylov subspace method which is suitable for general systems. More... | |
class | gko::solver::Fcg< ValueType > |
FCG or the flexible conjugate gradient method is an iterative type Krylov subspace method which is suitable for symmetric positive definite methods. More... | |
class | gko::solver::Gmres< ValueType > |
GMRES or the generalized minimal residual method is an iterative type Krylov subspace method which is suitable for nonsymmetric linear systems. More... | |
class | gko::solver::Idr< ValueType > |
IDR(s) is an efficient method for solving large nonsymmetric systems of linear equations. More... | |
class | gko::solver::Ir< ValueType > |
Iterative refinement (IR) is an iterative method that uses another coarse method to approximate the error of the current solution via the current residual. More... | |
class | gko::solver::LowerTrs< ValueType, IndexType > |
LowerTrs is the triangular solver which solves the system L x = b, when L is a lower triangular matrix. More... | |
class | gko::solver::UpperTrs< ValueType, IndexType > |
UpperTrs is the triangular solver which solves the system U x = b, when U is an upper triangular matrix. More... | |
Macros | |
#define | GKO_CREATE_FACTORY_PARAMETERS(_parameters_name, _factory_name) |
This Macro will generate a new type containing the parameters for the factory _factory_name . More... | |
#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 defined in. More... | |
#define | GKO_ENABLE_BUILD_METHOD(_factory_name) |
Defines a build method for the factory, simplifying its construction by removing the repetitive typing of factory's name. More... | |
#define | GKO_FACTORY_PARAMETER(_name, ...) |
Creates a factory parameter in the factory parameters structure. More... | |
#define | GKO_FACTORY_PARAMETER_SCALAR(_name, _default) GKO_FACTORY_PARAMETER(_name, _default) |
Creates a scalar factory parameter in the factory parameters structure. More... | |
#define | GKO_FACTORY_PARAMETER_VECTOR(_name, ...) GKO_FACTORY_PARAMETER(_name, __VA_ARGS__) |
Creates a vector factory parameter in the factory parameters structure. More... | |
Typedefs | |
template<typename ConcreteFactory , typename ConcreteLinOp , typename ParametersType , typename PolymorphicBase = LinOpFactory> | |
using | gko::EnableDefaultLinOpFactory = EnableDefaultFactory< ConcreteFactory, ConcreteLinOp, ParametersType, PolymorphicBase > |
This is an alias for the EnableDefaultFactory mixin, which correctly sets the template parameters to enable a subclass of LinOpFactory. More... | |
A module dedicated to the implementation and usage of the Linear operators in Ginkgo.
Below we elaborate on one of the most important concepts of Ginkgo, the linear operator. The linear operator (LinOp) is a base class for all linear algebra objects in Ginkgo. The main benefit of having a single base class for the entire collection of linear algebra objects (as opposed to having separate hierarchies for matrices, solvers and preconditioners) is the generality it provides.
A common interface often allows for writing more generic code. If a user's routine requires only operations provided by the LinOp interface, the same code can be used for any kind of linear operators, independent of whether these are matrices, solvers or preconditioners. This feature is also extensively used in Ginkgo itself. For example, a preconditioner used inside a Krylov solver is a LinOp. This allows the user to supply a wide variety of preconditioners: either the ones which were designed to be used in this scenario (like ILU or block-Jacobi), a user-supplied matrix which is known to be a good preconditioner for the specific problem, or even another solver (e.g., if constructing a flexible GMRES solver).
For example, a matrix free implementation would require the user to provide an apply implementation and instead of passing the generated matrix to the solver, they would have to provide their apply implementation for all the executors needed and no other code needs to be changed. See The custom-matrix-format program example for more details.
The linear operator (LinOp) is a base class for all linear algebra objects in Ginkgo. The main benefit of having a single base class for the entire collection of linear algebra objects (as opposed to having separate hierarchies for matrices, solvers and preconditioners) is the generality it provides.
First, since all subclasses provide a common interface, the library users are exposed to a smaller set of routines. For example, a matrix-vector product, a preconditioner application, or even a system solve are just different terms given to the operation of applying a certain linear operator to a vector. As such, Ginkgo uses the same routine name, LinOp::apply() for each of these operations, where the actual operation performed depends on the type of linear operator involved in the operation.
Second, a common interface often allows for writing more generic code. If a user's routine requires only operations provided by the LinOp interface, the same code can be used for any kind of linear operators, independent of whether these are matrices, solvers or preconditioners. This feature is also extensively used in Ginkgo itself. For example, a preconditioner used inside a Krylov solver is a LinOp. This allows the user to supply a wide variety of preconditioners: either the ones which were designed to be used in this scenario (like ILU or block-Jacobi), a user-supplied matrix which is known to be a good preconditioner for the specific problem, or even another solver (e.g., if constructing a flexible GMRES solver).
A key observation for providing a unified interface for matrices, solvers, and preconditioners is that the most common operation performed on all of them can be expressed as an application of a linear operator to a vector:
Finally, direct manipulation of LinOp objects is rarely required in simple scenarios. As an illustrative example, one could construct a fixed-point iteration routine as follows:
Here, if is a matrix, LinOp::apply() refers to the matrix vector product, and
L->apply(a, b)
computes .
x->add_scaled(one.get(), b.get())
is the axpy
vector update .
The interesting part of this example is the apply() routine at line 4 of the function body. Since this routine is part of the LinOp base class, the fixed-point iteration routine can calculate a fixed point not only for matrices, but for any type of linear operator.
#define GKO_CREATE_FACTORY_PARAMETERS | ( | _parameters_name, | |
_factory_name | |||
) |
This Macro will generate a new type containing the parameters for the factory _factory_name
.
For more details, see GKO_ENABLE_LIN_OP_FACTORY(). It is required to use this macro before calling the macro GKO_ENABLE_LIN_OP_FACTORY(). It is also required to use the same names for all parameters between both macros.
_parameters_name | name of the parameters member in the class |
_factory_name | name of the generated factory type |
#define GKO_ENABLE_BUILD_METHOD | ( | _factory_name | ) |
Defines a build method for the factory, simplifying its construction by removing the repetitive typing of factory's name.
_factory_name | the factory for which to define the method |
#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 defined in.
It is required to first call the macro GKO_CREATE_FACTORY_PARAMETERS() before this one in order to instantiate the parameters type first.
The list of parameters for the factory should be defined in a code block after the macro definition, and should contain a list of GKO_FACTORY_PARAMETER_* declarations. The class should provide a constructor with signature _lin_op(const _factory_name *, std::shared_ptr<const LinOp>) which the factory will use a callback to construct the object.
A minimal example of a linear operator is the following:
```c++ struct MyLinOp : public EnableLinOp<MyLinOp> { GKO_ENABLE_LIN_OP_FACTORY(MyLinOp, my_parameters, Factory) { // a factory parameter named "my_value", of type int and default // value of 5 int GKO_FACTORY_PARAMETER_SCALAR(my_value, 5); // a factory parameter named my_pair
of type std::pair<int,int>
// and default value {5, 5} std::pair<int, int> GKO_FACTORY_PARAMETER_VECTOR(my_pair, 5, 5); }; // constructor needed by EnableLinOp explicit MyLinOp(std::shared_ptr<const Executor> exec) { : EnableLinOp<MyLinOp>(exec) {} // constructor needed by the factory explicit MyLinOp(const Factory *factory, std::shared_ptr<const LinOp> matrix) : EnableLinOp<MyLinOp>(factory->get_executor()), matrix->get_size()), // store factory's parameters locally my_parameters_{factory->get_parameters()}, { int value = my_parameters_.my_value; // do something with value }
_lin_op | concrete operator for which the factory is to be created [CRTP parameter] |
_parameters_name | name of the parameters member in the class (its type is <_parameters_name>_type , the protected member's name is <_parameters_name>_ , and the public getter's name is get_<_parameters_name>() ) |
_factory_name | name of the generated factory type |
#define GKO_FACTORY_PARAMETER | ( | _name, | |
... | |||
) |
Creates a factory parameter in the factory parameters structure.
_name | name of the parameter |
<strong>VA_ARGS</strong> | default value of the parameter |
#define GKO_FACTORY_PARAMETER_SCALAR | ( | _name, | |
_default | |||
) | GKO_FACTORY_PARAMETER(_name, _default) |
Creates a scalar factory parameter in the factory parameters structure.
Scalar in this context means that the constructor for this type only takes a single parameter.
_name | name of the parameter |
_default | default value of the parameter |
#define GKO_FACTORY_PARAMETER_VECTOR | ( | _name, | |
... | |||
) | GKO_FACTORY_PARAMETER(_name, __VA_ARGS__) |
Creates a vector factory parameter in the factory parameters structure.
Vector in this context means that the constructor for this type takes multiple parameters.
_name | name of the parameter |
_default | default value of the parameter |
using gko::EnableDefaultLinOpFactory = typedef EnableDefaultFactory<ConcreteFactory, ConcreteLinOp, ParametersType, PolymorphicBase> |
This is an alias for the EnableDefaultFactory mixin, which correctly sets the template parameters to enable a subclass of LinOpFactory.
ConcreteFactory | the concrete factory which is being implemented [CRTP parmeter] |
ConcreteLinOp | the concrete LinOp type which this factory produces, needs to have a constructor which takes a const ConcreteFactory *, and an std::shared_ptr<const LinOp> as parameters. |
ParametersType | a subclass of enable_parameters_type template which defines all of the parameters of the factory |
PolymorphicBase | parent of ConcreteFactory in the polymorphic hierarchy, has to be a subclass of LinOpFactory |