Struct MonotoneMuUpdate 

pub struct MonotoneMuUpdate {
    pub mu_init: Number,
    pub mu_min: Number,
    pub mu_max: Number,
    pub mu_linear_decrease_factor: Number,
    pub mu_superlinear_decrease_power: Number,
    pub tau_min: Number,
    pub barrier_tol_factor: Number,
    pub mu_target: Number,
    pub mu_allow_fast_monotone_decrease: bool,
    pub compl_inf_tol: Number,
    pub first_iter_resto: bool,
}

Fields

mu_init: Number

mu_min: Number

mu_max: Number

Upper bound on μ from IpMonotoneMuUpdate.cpp:RegisterOptions. Used to clamp mu_init at MuUpdate::initialize so the barrier doesn’t start above the registered ceiling regardless of what the user set. Default 1e5 mirrors upstream.

mu_linear_decrease_factor: Number

mu_superlinear_decrease_power: Number

tau_min: Number

barrier_tol_factor: Number

barrier_tol_factor from IpMonotoneMuUpdate.cpp:RegisterOptions. μ only decreases when the barrier subproblem error drops below barrier_tol_factor · μ.

mu_target: Number

mu_target floor — μ never goes below this regardless of the reduction formula. Defaults to 0 (the floor is mu_min).

mu_allow_fast_monotone_decrease: bool

mu_allow_fast_monotone_decrease from IpMonotoneMuUpdate.cpp:RegisterOptions. When true (the upstream default), the reduction loop keeps iterating while the sub-error stays below barrier_tol_factor · μ, allowing multiple consecutive μ reductions in one outer call. When false, the loop exits after the first successful reduction — useful on stiff problems where a runaway μ collapse destroys the line search.

compl_inf_tol: Number

Complementarity tolerance — option compl_inf_tol, default 1e-4 per IpAlgorithmRegOp.cpp. Enters the dynamic μ floor via min(tol, compl_inf_tol) / (barrier_tol_factor + 1) per IpMonotoneMuUpdate.cpp:CalcNewMuAndTau:215. Without this floor, μ can collapse to the absolute floor (mu_min) while primal infeasibility is still large — observed on SSINE/DECONVBNE.

first_iter_resto: bool

first_iter_resto_ flag from Algorithm/IpMonotoneMuUpdate.cpp:118-121,144,196. When set, the very next call to Self::update_barrier_parameter skips the μ-reduction loop entirely and clears the flag. Wired by the restoration sub-builder for the inner IPM (prefix "resto.") so the inner doesn’t immediately collapse μ on iteration 0 — it must use the resto_mu value that [crate::resto::init::RestoIterateInitializer::SetInitialIterates] seeded into data.curr_mu.

Implementations

impl MonotoneMuUpdate

pub fn new() -> Self

pub fn with_first_iter_resto(self, b: bool) -> Self

Builder helper for the first_iter_resto_ flag. Mirrors the upstream prefix == "resto." branch in IpMonotoneMuUpdate.cpp:InitializeImpl.

pub fn with_mu_min(self, mu_min: Number) -> Self

Builder for the mu_min floor. The restoration inner IPM uses 100 * outer_mu_min per upstream IpAdaptiveMuUpdate.cpp:206-211 (and the analogous monotone path); without the conservative floor, near-feasible iterates collapse μ to the absolute floor in a single step and the next direction is dominated by the penalty/proximity terms instead of the barrier, which destroys near-feasibility (DECONVBNE).

pub fn compute_tau(&self, mu: Number) -> Number

Fraction-to-the-bound parameter tau from upstream IpMonotoneMuUpdate.cpp:Update:

  tau = max(tau_min, 1 - mu)

Returns a value in [tau_min, 1).

pub fn compute_next_mu(&self, curr_mu: Number) -> Number

Pure scalar reduction used by the trait impl. Exposed so unit tests can drive the formula without standing up an IpoptData/IpoptCq fixture.

Trait Implementations

impl Default for MonotoneMuUpdate

fn default() -> Self

Returns the “default value” for a type.

impl MuUpdate for MonotoneMuUpdate

fn terminates_on_tiny_step(&self) -> bool

Monotone μ throws TINY_STEP_DETECTED when a tiny step is flagged and μ is already at its floor — see IpMonotoneMuUpdate.cpp. The main loop realises that throw as a STOP_AT_TINY_STEP termination.

fn initialize(&mut self, data: &IpoptDataHandle)

Port of IpMonotoneMuUpdate.cpp:InitializeImpl. Seeds curr_mu = min(mu_init, mu_max), curr_tau = max(tau_min, 1 - curr_mu).

fn update_barrier_parameter( &mut self, data: &IpoptDataHandle, cq: &IpoptCqHandle, _nlp: Option<&Rc<RefCell<dyn IpoptNlp>>>, _pd_search_dir: Option<&mut PdSearchDirCalc>, ) -> Number

Port of IpMonotoneMuUpdate.cpp:UpdateBarrierParameter. Reduces μ only while the barrier-subproblem error is below barrier_tol_factor · μ (or a tiny step was just detected). Each successful reduction also refreshes curr_tau and the new μ in data. Returns the post-update μ.