krypy.recycling.evaluators
 evaluators for deflation vector candidates¶

class
krypy.recycling.evaluators.
RitzApproxKrylov
(mode='extrapolate', tol=None, pseudospectra=False, bound_pseudo_kwargs=None, deflweight=1.0)¶ Bases:
krypy.recycling.evaluators._RitzSubsetEvaluator
Evaluates a choice of Ritz vectors with a tailored approximate Krylov subspace method.
Parameters:  mode –
(optional) determines how the number of iterations is estimated. Must be one of the following:
extrapolate
(default): use the iteration count where the extrapolation of the smallest residual reduction over all steps drops below the tolerance.direct
: use the iteration count where the predicted residual bound drops below the tolerance. May result in severe underestimation ifpseudospectra==False
.
 pseudospectra – (optional) should pseudospectra be computed
for the given problem? With
pseudospectra=True
, a prediction may not be possible due to unfulfilled assumptions for the computation of the pseudospectral bound.  bound_pseudo_kwargs – (optional) a dictionary with arguments
that are passed to
bound_pseudo()
.  deflweight – (optional) see
estimate_time()
. Defaults to 1.

evaluate
(ritz, subset)¶ Returns a list of subsets with indices of Ritz vectors that are considered for deflation.
 mode –

class
krypy.recycling.evaluators.
RitzApriori
(Bound, tol=None, strategy='simple', deflweight=1.0)¶ Bases:
krypy.recycling.evaluators._RitzSubsetEvaluator
Evaluates a choice of Ritz vectors with an apriori bound for selfadjoint problems.
Parameters:  Bound – the apriori bound which is used for estimating the convergence behavior.
 tol – (optional) the tolerance for the stopping criterion, see
_KrylovSolver
. If None is provided (default), then the tolerance is retrieved from ritz._deflated_solver.tol in the call toevaluate()
.  strategy –
(optional) the following strategies are available
 simple: (default) uses the Ritz values that are complementary to the deflated ones for the evaluation of the bound.
 intervals: uses intervals around the Ritz values that are considered with simple. The intervals incorporate possible changes in the operators.

evaluate
(ritz, subset)¶ Returns a list of subsets with indices of Ritz vectors that are considered for deflation.