gko::stop::Criterion#

Abstract base for all stopping criteria. The factory (a CriterionFactory) takes the system matrix, the right-hand side, the initial guess and, optionally, the initial residual (CriterionArgs). The resulting Criterion is queried every iteration through update(), which collects the iteration count, residual, residual norm, implicit squared residual norm and solution, followed by check(). Custom criteria derive from Criterion and override check_impl.

class Criterion #

Inherits from

The Criterion class is a base class for all stopping criteria. It contains a factory to instantiate criteria. It is up to each specific stopping criterion to decide what to do with the data that is passed to it.

Note that depending on the criterion, convergence may not have happened after stopping.

Subclassed by

Public Functions

inline Updater update()#

Returns the updater object

Returns:

the updater object

inline 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. The actual implantation of the criterion goes here.

Parameters:

  • stopping_id – id of the stopping criterion

  • set_finalized – Controls if the current version should count as finalized or not

  • stop_status – status of the stopping criterion

  • one_changed – indicates if the status of a vector has changed

  • updater – the Updater object containing all the information

Returns:

whether convergence was completely reached

class Updater#

The Updater class serves for convenient argument passing to the Criterion’s check function. The pattern used is a Builder, except Updater builds a function’s arguments before calling the function itself, and does not build an object. This allows calling a Criterion’s check in the form

stop_criterion->update()
    .num_iterations(num_iterations)
    .ignore_residual_check(ignore_residual_check)
    .residual_norm(residual_norm)
    .implicit_sq_residual_norm(implicit_sq_residual_norm)
    .residual(residual)
    .solution(solution)
    .check(converged);

If there is a need for a new form of data to pass to the Criterion, it should be added here.

Public Functions

Updater(const Updater&) = delete#

Prevent copying and moving the object This is to enforce the use of argument passing and calling check at the same time.

inline bool check(
uint8 stopping_id,
bool set_finalized,
array<stopping_status> *stop_status,
bool *one_changed,
) const#

Calls the parent Criterion object’s check method