Trait BacktrackingLsAcceptor 

pub trait BacktrackingLsAcceptor {
    // Required method
    fn reset(&mut self);

    // Provided methods
    fn init_this_line_search(
        &mut self,
        _data: &IpoptDataHandle,
        _cq: &IpoptCqHandle,
        _delta: &IteratesVector,
    ) { ... }
    fn calc_alpha_min(&mut self, _d_phi: Number, _theta: Number) -> Number { ... }
    fn check_trial_point(
        &mut self,
        _alpha_primal: Number,
        _theta: Number,
        _phi: Number,
        _d_phi: Number,
        _theta_trial: Number,
        _phi_trial: Number,
    ) -> AcceptDecision { ... }
    fn update_for_next_iteration(
        &mut self,
        _alpha_primal: Number,
        _theta: Number,
        _phi: Number,
        _d_phi: Number,
        _phi_trial: Number,
    ) -> char { ... }
    fn make_orig_progress_check(
        &self,
        _reference_theta: Number,
        _reference_barr: Number,
        _obj_max_inc: Number,
    ) -> Option<OrigProgressCallback> { ... }
    fn prepare_resto_phase_start(
        &mut self,
        _reference_theta: Number,
        _reference_barr: Number,
    ) { ... }
    fn set_theta_max_fact(&mut self, _theta_max_fact: Number) { ... }
}

Acceptor side of the backtracking line search. Concrete impls: super::filter_acceptor::FilterLsAcceptor (Phase 7), PenaltyLsAcceptor (Phase 10), CGPenaltyLsAcceptor (Phase 10).

The driver calls check_trial_point on each backtracking step. Acceptors that need the trial-iterate components (rather than scalar (theta, phi)) can extend this surface in later phases — the filter acceptor only needs the four scalars upstream feeds in at line IpFilterLSAcceptor.cpp:CheckAcceptabilityOfTrialPoint.

Required Methods

fn reset(&mut self)

Reset acceptor state for a new outer iteration.

Provided Methods

fn init_this_line_search( &mut self, _data: &IpoptDataHandle, _cq: &IpoptCqHandle, _delta: &IteratesVector, )

Hook called once per outer iteration, after the search direction delta has been computed and before the α-loop. Mirrors IpPenaltyLSAcceptor.cpp:InitThisLineSearch — the penalty acceptor uses it to snapshot reference (θ, φ, ∇φᵀδ, δᵀWδ) and to bump the penalty parameter ν. Default: no-op (filter acceptor has nothing to cache between α-loop iterations).

fn calc_alpha_min(&mut self, _d_phi: Number, _theta: Number) -> Number

Compute the minimum primal step length below which the driver should declare a tiny step / hand off to restoration. Mirrors IpFilterLSAcceptor.cpp:CalculateAlphaMin — the value depends on the current (theta, d_phi) pair (the directional derivative of the barrier objective along the search step) and on the acceptor’s lazily-initialised theta_min. Default impl returns 0.0 so non-filter acceptors degenerate to the driver’s own absolute alpha_min floor.

fn check_trial_point( &mut self, _alpha_primal: Number, _theta: Number, _phi: Number, _d_phi: Number, _theta_trial: Number, _phi_trial: Number, ) -> AcceptDecision

Decide whether the trial (theta_trial, phi_trial) at primal step alpha_primal is acceptable, given the current iterate’s (theta, phi) and the directional derivative d_phi. Default: always accept (lets stub acceptors compose without interfering with the driver’s α-loop).

Mutable receiver so concrete acceptors (notably super::filter_acceptor::FilterLsAcceptor) can record per-trial state used by the filter-reset heuristic (IpFilterLSAcceptor.cpp:407-433).

fn update_for_next_iteration( &mut self, _alpha_primal: Number, _theta: Number, _phi: Number, _d_phi: Number, _phi_trial: Number, ) -> char

Post-accept hook — port of IpFilterLSAcceptor::UpdateForNextIteration. Both decides the info_alpha_primal_char tag and augments the filter when upstream would. Returns:

• 'f' — F-type Armijo step (IsFtype && ArmijoHolds); filter is not augmented.
• 'h' — anything else (!IsFtype || !ArmijoHolds); filter is augmented with (theta_add, phi_add) = ((1 - γ_θ)·θ_ref, φ_ref - γ_φ·θ_ref).

The driver calls this once per accepted step, after check_trial_point returns Accept and before accept_trial_point promotes trial → curr. Default impl returns 'h' (no filter), so non-filter acceptors remain valid.

fn make_orig_progress_check( &self, _reference_theta: Number, _reference_barr: Number, _obj_max_inc: Number, ) -> Option<OrigProgressCallback>

Build the orig-progress callback the inner restoration IPM should consult to decide whether the recovered iterate is acceptable to this (outer) acceptor’s filter and reference iterate. Mirrors upstream IpRestoFilterConvCheck::SetOrigLSAcceptor / TestOrigProgress. Default returns None — penalty / CG-penalty acceptors do not gate restoration on a filter, so they fall through to the kappa-reduction-only guard.

reference_theta and reference_barr are the outer iterate’s (curr_constraint_violation, curr_barrier_obj) at restoration entry; obj_max_inc is the upstream obj_max_inc option (default 5.0).

fn prepare_resto_phase_start( &mut self, _reference_theta: Number, _reference_barr: Number, )

Hook called by the algorithm immediately before invoking the restoration phase — port of IpFilterLSAcceptor::PrepareRestoPhaseStart → AugmentFilter (IpFilterLSAcceptor.cpp:898-901, called from IpBacktrackingLineSearch.cpp:566). The filter acceptor augments the filter with the resto-entry iterate’s shrunk envelope ((1 - γ_θ)·θ_ref, φ_ref - γ_φ·θ_ref). After restoration recovers, the outer’s Newton step is then forced by the filter to make real progress vs the entry point — without this, the outer can accept null-progress ‘h’ steps and re-enter restoration (observed on DECONVBNE: 323 R-accepts vs ipopt’s 21). Default: no-op for non-filter acceptors.

fn set_theta_max_fact(&mut self, _theta_max_fact: Number)

Override the filter acceptor’s theta_max_fact (default 1e4). Used by the resto sub-IPM wiring to bump the gate to 1e8, which mirrors upstream IpRestoMinC_1Nrm.cpp:91 (resto.theta_max_fact = 1e8). Without this override the inner IPM’s first line search caps theta_max = 1e4 (since reference θ ≈ 0 after slack init), and the first non-trivial trial whose resto-NLP θ_trial exceeds 1e4 is rejected at the theta_max gate before reaching f-type/Armijo dispatch. Default: no-op for non-filter acceptors.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl BacktrackingLsAcceptor for FilterLsAcceptor

impl BacktrackingLsAcceptor for PenaltyLsAcceptor