Struct BacktrackingLineSearch 

pub struct BacktrackingLineSearch {

    pub acceptor: Box<dyn BacktrackingLsAcceptor>,
    pub alpha_red_factor: Number,
    pub max_soc: i32,
    pub kappa_soc: Number,
    pub soc_method: i32,
    pub watchdog_shortened_iter_trigger: i32,
    pub watchdog_trial_iter_max: i32,
    pub alpha_min: Number,
    pub max_trials: i32,
    pub soft_resto_pderror_reduction_factor: Number,
    pub max_soft_resto_iters: i32,
    pub accept_every_trial_step: bool,
    pub alpha_for_y: AlphaForY,
    /* private fields */
}

Fields

acceptor: Box<dyn BacktrackingLsAcceptor>

alpha_red_factor: Number

max_soc: i32

kappa_soc: Number

Threshold for the SOC outer-loop convergence test theta_trial <= kappa_soc * theta_soc_old. Mirrors upstream’s kappa_soc (default 0.99).

soc_method: i32

SOC RHS variant. 0 = upstream default (“old”), 1 = scaled gradient-block variant. Both correspond to upstream’s soc_method option.

watchdog_shortened_iter_trigger: i32

Number of consecutive shortened iterations before the watchdog procedure activates. Disabled when <= 0. Mirrors upstream’s watchdog_shortened_iter_trigger (default 10).

watchdog_trial_iter_max: i32

Maximum number of outer iterations the watchdog will accept non-decreasing trial points before reverting to the snapshot. Mirrors upstream’s watchdog_trial_iter_max (default 3).

alpha_min: Number

Lower bound on α; below this we declare a tiny step (mirrors alpha_min_frac flow, IpBacktrackingLineSearch.cpp:CalculateAlphaMin).

max_trials: i32

Maximum trial-iteration cap before declaring failure.

soft_resto_pderror_reduction_factor: Number

Required relative reduction in the primal-dual system error for a soft-resto step to be accepted. 0 disables soft restoration. Mirrors upstream soft_resto_pderror_reduction_factor (default 1 - 1e-4).

max_soft_resto_iters: i32

Cap on consecutive soft-resto iterations before full restoration is forced. Mirrors upstream max_soft_resto_iters (default 10).

accept_every_trial_step: bool

accept_every_trial_step — when true, the alpha loop and filter are bypassed: the FTB-truncated alpha_init/alpha_dual step is set as the trial and accepted unconditionally. Mirrors upstream’s IpBacktrackingLineSearch.cpp:accept_every_trial_step_ short-circuit at the top of FindAcceptableTrialPoint.

alpha_for_y: AlphaForY

alpha_for_y policy applied to the equality multipliers y_c, y_d when constructing the trial iterate. See AlphaForY.

Implementations

impl BacktrackingLineSearch

pub fn new(acceptor: Box<dyn BacktrackingLsAcceptor>) -> Self

pub fn acceptor(&self) -> &dyn BacktrackingLsAcceptor

pub fn acceptor_mut(&mut self) -> &mut dyn BacktrackingLsAcceptor

pub fn reset(&mut self)

Reset the acceptor state at the start of a new outer iteration.

pub fn find_acceptable_trial_point( &mut self, data: &IpoptDataHandle, cq: &IpoptCqHandle, delta: &IteratesVector, alpha_init: Number, alpha_dual: Number, nlp: Option<&Rc<RefCell<dyn IpoptNlp>>>, search_dir: Option<&mut PdSearchDirCalc>, ) -> Outcome

Public line-search entry point. Wraps the regular filter line search (Self::run_filter_line_search) with the soft restoration phase — port of the in_soft_resto_phase_ state machine in IpBacktrackingLineSearch::FindAcceptableTrialPoint (IpBacktrackingLineSearch.cpp:439-465 for the in-phase continuation, :528-556 for entering the phase).

Outcomes:

• Accepted: a trial point is in data.trial — either a regular filter/watchdog step or a soft-resto step (info char ‘s’ = stay in soft resto, ‘S’ = step also satisfies the original filter so soft resto is left).
• TinyStep / Failed: neither the regular line search nor a soft-resto step could make progress; the caller hands off to the full restoration phase.