petsc-3.3-p7 2013-05-11

SNESLineSearchShellSetUserFunc

Sets the user function for the SNESLineSearch Shell implementation.

PetscErrorCode SNESLineSearchShellSetUserFunc(SNESLineSearch linesearch, SNESLineSearchUserFunc func, void *ctx)

Not Collective

	linesearch	- SNESLineSearch context
	func	- function implementing the linesearch shell.
	ctx	- context for func

	linesearch	- the linesearch instance
	ctx	- the above mentioned context

 PetscErrorCode shellfunc(SNESLineSearch linesearch, void * ctx) {

    Vec  X, Y, F, W, G;

    SNES snes;

    PetscFunctionBegin;

    ierr = SNESLineSearchGetSNES(linesearch, &snes);CHKERRQ(ierr);

    ierr = SNESLineSearchSetSuccess(linesearch, PETSC_TRUE);CHKERRQ(ierr);

    ierr = SNESLineSearchGetVecs(linesearch, X, Y, F, W, G);CHKERRQ(ierr);

    .. determine lambda using W and G as work vecs..

    ierr = VecAXPY(X, -lambda, Y);CHKERRQ(ierr);

    ierr = SNESComputeFunction(snes, X, F);CHKERRQ(ierr);

    ierr = SNESLineSearchComputeNorms(linesearch);CHKERRQ(ierr);

    PetscFunctionReturn(0);

...

 ierr = SNESGetSNESLineSearch(snes, &linesearch);CHKERRQ(ierr);

 ierr = SNESLineSearchSetType(linesearch, SNESLINESEARCHSHELL);CHKERRQ(ierr);

 ierr = SNESLineSearchShellSetUserFunc(linesearch, shellfunc, PETSC_NULL);CHKERRQ(ierr);

.keywords: SNESLineSearch, Shell, user, function, set