SNESLineSearchSetPreCheck

Sets a routine to check the validity of a new direction given by the linear solve before the line search is called.

PetscErrorCode PETSCSNES_DLLEXPORT SNESLineSearchSetPreCheck(SNES snes,PetscErrorCode (*func)(SNES,Vec,Vec,void*,PetscTruth*),void *checkctx)

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

Collective on SNES

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

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

	snes	- nonlinear context
	checkctx	- optional user-defined context for use by step checking routine
	x	- previous iterate
	y	- new search direction and length

	y	- search direction (possibly changed)
	changed_y	- indicates search direction was changed by this routine

Notes: All line searches accept the new iterate computed by the line search checking routine.

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