petscmain 20210420
PCFieldSplitSetGKBDelay
Sets the delay in the lower bound error estimate in the generalized GolubKahan bidiagonalization preconditioner.
Synopsis
#include "petscpc.h"
PetscErrorCode PCFieldSplitSetGKBDelay(PC pc,PetscInt delay)
Collective on PC
Notes
The algorithm uses a lower bound estimate of the error in energy norm as stopping criterion. The lower bound of the error uu^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 GolubKahan bidiagonalization method and its lower bound stopping criterion, please refer to
[Ar13] Generalized GolubKahan bidiagonalization and stopping criteria, SIAM J. Matrix Anal. Appl., Vol. 34, No. 2, pp. 571592, 2013.
Input Parameters
 pc   the preconditioner context

 delay   the delay window in the lower bound estimate

Options Database
 pc_fieldsplit_gkb_delay   default is 5

See Also
PCFIELDSPLIT, PCFieldSplitSetGKBNu(), PCFieldSplitSetGKBTol(), PCFieldSplitSetGKBMaxit()
Level
intermediate
Location
src/ksp/pc/impls/fieldsplit/fieldsplit.c
Implementations
PCFieldSplitSetGKBDelay_FieldSplit in src/ksp/pc/impls/fieldsplit/fieldsplit.c
Index of all PC routines
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Index of all manual pages