gko::stop::ResidualNorm< ValueType > Class Template Reference

Stopping criterion based on the explicit residual norm \( \| r_k \| = \| b - A x_k \| \). More...

#include <ginkgo/core/stop/residual_norm.hpp>

Inheritance diagram for gko::stop::ResidualNorm< ValueType >:

Collaboration diagram for gko::stop::ResidualNorm< ValueType >:

Classes
class	Factory
struct	parameters_type

Public Types
using	ComplexVector = matrix::Dense< to_complex< ValueType > >
using	NormVector = matrix::Dense< remove_complex< ValueType > >
using	Vector = matrix::Dense< ValueType >

Public Member Functions
const parameters_type &	get_parameters () const
Public Member Functions inherited from gko::stop::Criterion
Updater	update ()
	Returns the updater object. More...
bool	check (uint8 stopping_id, bool set_finalized, array< stopping_status > *stop_status, bool *one_changed, const Updater &updater)
	This checks whether convergence was reached for a certain criterion. More...
Public Member Functions inherited from gko::PolymorphicObject
virtual void	validate_data () const
	Throws gko::InvalidData exception if we found the data inside the object does not fulfill certain property up to our knowledge.
PolymorphicObject &	operator= (const PolymorphicObject &)
std::shared_ptr< const Executor >	get_executor () const noexcept
	Returns the Executor of the object. More...
Public Member Functions inherited from gko::log::EnableLogging< PolymorphicObject >
void	add_logger (std::shared_ptr< const Logger > logger) override
void	remove_logger (const Logger *logger) override
void	remove_logger (ptr_param< const Logger > logger)
const std::vector< std::shared_ptr< const Logger > > &	get_loggers () const override
void	clear_loggers () override
Public Member Functions inherited from gko::log::Loggable
void	remove_logger (ptr_param< const Logger > logger)

Static Public Member Functions
static auto	build () -> decltype(Factory ::create())

Detailed Description

template<typename ValueType = default_precision>
class gko::stop::ResidualNorm< ValueType >

Stopping criterion based on the explicit residual norm \( \| r_k \| = \| b - A x_k \| \).

The iteration halts once \( \| r_k \| \le \tau \cdot \beta \), where \(\tau\) is the factory parameter reduction_factor and the baseline \(\beta\) is selected by the baseline factory parameter:

• mode::rhs_norm (default) — relative to the right-hand side: \( \beta = \| b \| \), so the condition is \( \| r_k \| \le \tau \| b \| \).
• mode::initial_resnorm — relative to the initial residual: \( \beta = \| r_0 \| \), so the condition is \( \| r_k \| \le \tau \| r_0 \| \).
• mode::absolute — absolute threshold: \( \beta = 1 \), so the condition is \( \| r_k \| \le \tau \).

Per-iteration, the criterion prefers a pre-computed residual norm passed by the solver (via Updater::residual_norm); otherwise it falls back to computing the 2-norm of the residual vector itself (via Updater::residual), which costs one global reduction. When even cheaper checks are needed and the solver maintains an internal squared-norm estimate, use ImplicitResidualNorm instead.

Note

Baseline prerequisites at construction time:

• mode::rhs_norm requires the right-hand side \( b \).
• mode::initial_resnorm requires either the initial residual \( r_0 \) explicitly, or the triple \( (A, b, x_0) \) from which it is computed as \( r_0 = b - A x_0 \).
• mode::absolute requires \( b \) as well — to determine the number of right-hand sides; its baseline is then filled with ones. If the required arguments are missing, ::gko::NotSupported() is thrown.

---

The documentation for this class was generated from the following file:

• ginkgo/core/stop/residual_norm.hpp