retry_evaluate()

template<typename Update , typename Proposal , typename Curr , typename Prev , typename Eval , typename P , typename Backoff >

auto stan::math::internal::retry_evaluate ( Update &&  update, Proposal &&  proposal, Curr &&  curr, Prev &&  prev, Eval &  eval, P &&  p, Backoff &&  backoff  )

inline

Retry evaluation of a step until it passes a validity check.

The update callable is invoked with (curr, prev, eval, p) and is expected to fill eval (at eval.alpha()) with the objective and directional derivative. If the evaluation is not valid, the backoff callable should shrink eval.alpha() and return whether another retry should be attempted. The validity check can inspect the evaluation and, for non-void updates, the returned status.

Template Parameters

Update	Callable that performs one evaluation step. Must accept 4 arguments.
Proposal	Proposed step type passed to update.
Curr	Current state type passed to update.
Prev	Previous state type passed to update.
Eval	Evaluation record containing alpha/obj/dir.
P	Search direction type passed to update.
Backoff	Callable that shrinks eval.alpha() and returns a bool.

Parameters

[in]	update	Evaluator invoked as update(curr, prev, eval, p).
[in,out]	proposal	Proposed step forwarded to update.
[in]	curr	Current state forwarded to update.
[in]	prev	Previous state forwarded to update.
[in,out]	eval	Evaluation record, updated in-place by update.
[in]	p	Search direction forwarded to update.
[in]	backoff	Shrinks alpha and returns whether another retry should occur.

Returns

For void updates, returns void. Otherwise returns the value from the first valid evaluation.

Definition at line 579 of file wolfe_line_search.hpp.