petsc-3.8.4 2018-03-24

SNESLineSearchPreCheckPicard

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

Synopsis

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

Logically Collective on SNESLineSearch

Input Arguments

	linesearch	- linesearch context
	X	- base state for this step
	Y	- initial correction
	ctx	- context for this function

Output Arguments

	Y	- correction, possibly modified
	changed	- flag indicating that Y was modified

Options Database Key

	-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". This correction is generally not useful when using a Newton linearization.

Reference

Hindmarsh and Payne (1996) Time step limits for stable solutions of the ice sheet equation, Annals of Glaciology.

Examples

src/snes/examples/tutorials/ex15.c.html