SNESSetLineSearchCheck

Sets a routine to check the validity of new iterate computed by the line search routine in the Newton-based method SNESLS.

Synopsis

int SNESSetLineSearchCheck(SNES snes,int (*func)(SNES,void*,Vec,PetscTruth*),void *checkctx)

Input Parameters

	snes	- nonlinear context obtained from SNESCreate()
	func	- pointer to int function
	checkctx	- optional user-defined context for use by step checking routine

Collective on SNES

Calling sequence of func

   int func (SNES snes, void *checkctx, Vec x, PetscTruth *flag)

where func returns an error code of 0 on success and a nonzero on failure.

Input parameters for func

	snes	- nonlinear context
	checkctx	- optional user-defined context for use by step checking routine
	x	- current candidate iterate

Output parameters for func

	x	- current iterate (possibly modified)
	flag	- flag indicating whether x has been modified (either PETSC_TRUE of PETSC_FALSE)

Notes

SNESNoLineSearch() and SNESNoLineSearchNoNorms() accept the new iterate computed by the line search checking routine. In particular, these routines (1) compute a candidate iterate u_{i+1}, (2) pass control to the checking routine, and then (3) compute the corresponding nonlinear function f(u_{i+1}) with the (possibly altered) iterate u_{i+1}.

SNESQuadraticLineSearch() and SNESCubicLineSearch() also accept the new iterate computed by the line search checking routine. In particular, these routines (1) compute a candidate iterate u_{i+1} as well as a candidate nonlinear function f(u_{i+1}), (2) pass control to the checking routine, and then (3) force a re-evaluation of f(u_{i+1}) if any changes were made to the candidate iterate in the checking routine (as indicated by flag=PETSC_TRUE). The overhead of this function re-evaluation can be very costly, so use this feature with caution!

Keywords

SNES, nonlinear, set, line search check, step check, routine

Examples

src/snes/examples/tutorials/ex3.c.html