Source code for implementations.convergence_controller_classes.check_convergence
import numpy as np
from pySDC.core.convergence_controller import ConvergenceController
[docs]
class CheckConvergence(ConvergenceController):
"""
Perform simple checks on convergence for SDC iterations.
Iteration is terminated via one of two criteria:
- Residual tolerance
- Maximum number of iterations
"""
[docs]
def setup(self, controller, params, description, **kwargs):
"""
Define default parameters here
Args:
controller (pySDC.Controller): The controller
params (dict): The params passed for this specific convergence controller
description (dict): The description object used to instantiate the controller
Returns:
(dict): The updated params dictionary
"""
defaults = {'control_order': +200, 'use_e_tol': 'e_tol' in description['level_params'].keys()}
return {**defaults, **super().setup(controller, params, description, **kwargs)}
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def dependencies(self, controller, description, **kwargs):
"""
Load the embedded error estimator if needed.
Args:
controller (pySDC.Controller): The controller
description (dict): The description object used to instantiate the controller
Returns:
None
"""
if self.params.useMPI:
self.prepare_MPI_logical_operations()
super().dependencies(controller, description)
if self.params.use_e_tol:
from pySDC.implementations.convergence_controller_classes.estimate_embedded_error import (
EstimateEmbeddedError,
)
controller.add_convergence_controller(
EstimateEmbeddedError,
description=description,
)
return None
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@staticmethod
def check_convergence(S, self=None):
"""
Check the convergence of a single step.
Test the residual and max. number of iterations as well as allowing overrides to both stop and continue.
Args:
S (pySDC.Step): The current step
Returns:
bool: Convergence status of the step
"""
# do all this on the finest level
L = S.levels[0]
# get residual and check against prescribed tolerance (plus check number of iterations)
iter_converged = S.status.iter >= S.params.maxiter
res_converged = L.status.residual <= L.params.restol and (S.status.iter > 0 or L.status.sweep > 0)
e_tol_converged = (
L.status.increment < L.params.e_tol if (L.params.get('e_tol') and L.status.get('increment')) else False
)
converged = (
iter_converged or res_converged or e_tol_converged or S.status.force_done
) and not S.status.force_continue
if converged is None:
converged = False
# print information for debugging
if converged and self:
self.debug(
f'Declared convergence: maxiter reached[{"x" if iter_converged else " "}] restol reached[{"x" if res_converged else " "}] e_tol reached[{"x" if e_tol_converged else " "}]',
S,
)
return converged
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def check_iteration_status(self, controller, S, **kwargs):
"""
Routine to determine whether to stop iterating (currently testing the residual + the max. number of iterations)
Args:
controller (pySDC.Controller.controller): The controller
S (pySDC.Step.step): The current step
Returns:
None
"""
S.status.done = self.check_convergence(S, self)
if "comm" in kwargs.keys():
self.communicate_convergence(controller, S, **kwargs)
S.status.force_continue = False
return None
[docs]
def communicate_convergence(self, controller, S, comm):
"""
Communicate the convergence status during `check_iteration_status` if MPI is used.
Args:
controller (pySDC.Controller): The controller
S (pySDC.Step.step): The current step
comm (mpi4py.MPI.Comm): MPI communicator
Returns:
None
"""
# Either gather information about all status or send forward own
if controller.params.all_to_done:
for hook in controller.hooks:
hook.pre_comm(step=S, level_number=0)
S.status.done = comm.allreduce(sendobj=S.status.done, op=self.MPI_LAND)
S.status.force_done = comm.allreduce(sendobj=S.status.force_done, op=self.MPI_LOR)
for hook in controller.hooks:
hook.post_comm(step=S, level_number=0, add_to_stats=True)
S.status.done = S.status.done or S.status.force_done
else:
for hook in controller.hooks:
hook.pre_comm(step=S, level_number=0)
# check if an open request of the status send is pending
controller.wait_with_interrupt(request=controller.req_status)
if S.status.force_done:
return None
# recv status
if not S.status.first and not S.status.prev_done:
buff = np.empty(1, dtype=bool)
self.Recv(comm, source=S.status.slot - 1, buffer=[buff, self.MPI_BOOL])
S.status.prev_done = buff[0]
S.status.done = S.status.done and S.status.prev_done
# send status forward
if not S.status.last:
buff = np.empty(1, dtype=bool)
buff[0] = S.status.done
self.Send(comm, dest=S.status.slot + 1, buffer=[buff, self.MPI_BOOL])
for hook in controller.hooks:
hook.post_comm(step=S, level_number=0, add_to_stats=True)