PCFieldSplitSetGKBDelay#
Sets the delay in the lower bound error estimate in the generalized Golub-Kahan bidiagonalization [Ari13] in PCFIELDSPLIT preconditioner.
Synopsis#
#include "petscpc.h" 
PetscErrorCode PCFieldSplitSetGKBDelay(PC pc, PetscInt delay)
Collective
Input Parameters#
- pc - the preconditioner context 
- delay - the delay window in the lower bound estimate 
Options Database Key#
- -pc_fieldsplit_gkb_delay - - default is 5
Notes#
The algorithm uses a lower bound estimate of the error in energy norm as stopping criterion. The lower bound of the error \( ||u-u^k||_H \)
is expressed as a truncated sum. The error at iteration k can only be measured at iteration (k + delay), and thus the algorithm needs
at least (delay + 1) iterations to stop.
For more details on the generalized Golub-Kahan bidiagonalization method and its lower bound stopping criterion, please refer to [Ari13]
References#
See Also#
Solving Block Matrices with PCFIELDSPLIT, PC, PCFIELDSPLIT, PCFieldSplitSetGKBNu(), PCFieldSplitSetGKBTol(), PCFieldSplitSetGKBMaxit()
Level#
intermediate
Location#
Implementations#
PCFieldSplitSetGKBDelay_FieldSplit() in src/ksp/pc/impls/fieldsplit/fieldsplit.c
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