PCFieldSplitSetGKBDelay#

Sets the delay in the lower bound error estimate in the generalized Golub-Kahan bidiagonalization 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

Note#

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

References#

[Ar13] Generalized Golub-Kahan bidiagonalization and stopping criteria, SIAM J. Matrix Anal. Appl., Vol. 34, No. 2, pp. 571-592, 2013.

See Also#

Solving Block Matrices, PC, 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

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