SNESLineSearchPreCheckPicard

Implements a correction that is sometimes useful to improve the convergence rate of Picard iteration [HP96]

Synopsis

#include "petscsnes.h" 
PetscErrorCode SNESLineSearchPreCheckPicard(SNESLineSearch linesearch, Vec X, Vec Y, PetscBool *changed, void *ctx)

Logically Collective

Input Parameters

• linesearch - the line search context

• X - base state for this step

• ctx - context for this function

Input/Output Parameter

• Y - correction, possibly modified

Output Parameter

• changed - flag indicating that Y was modified

Options Database Keys

• -snes_linesearch_precheck_picard - activate this routine

• -snes_linesearch_precheck_picard_angle - angle

Notes

This function should be passed to SNESLineSearchSetPreCheck()

The justification for this method involves the linear convergence of a Picard iteration so the Picard linearization should be provided in place of the “Jacobian” [HP96]. This correction is generally not useful when using a Newton linearization.

Developer Note

The use of PetscObjectGetState() would eliminate the need for the changed argument to be provided

References

[HP96] (1,2)

Richard CA Hindmarsh and Antony J Payne. Time-step limits for stable solutions of the ice-sheet equation. Annals of Glaciology, 23:74–85, 1996.

See Also

SNES: Nonlinear Solvers, SNES, SNESLineSearch, SNESSetPicard(), SNESGetLineSearch(), SNESLineSearchSetPreCheck(), SNESLineSearchSetPostCheck()

Level

advanced

Location

src/snes/linesearch/interface/linesearch.c

Examples

src/snes/tutorials/ex15.c

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