Struct OuterGradientFdAudit 

pub struct OuterGradientFdAudit {
    pub value: f64,
    pub components: Vec<OuterGradientFdComponent>,
    pub hessian_eigenvalues: Vec<f64>,
}

Result of a component-by-component finite-difference audit of an outer REML/LAML gradient at a fixed θ, plus the outer-Hessian eigenvalues.

This is the discriminating diagnostic that forks the two failure modes of a non-terminating outer loop: an objective↔gradient desync (analytic ≠ FD on some component → the trust region chases a phantom descent direction forever) versus weak identifiability (analytic ≈ FD everywhere but a near-zero outer-Hessian eigenvalue → a genuinely flat valley the optimizer crawls along). It is family-agnostic: any path that exposes an outer evaluator closure θ ↦ (V, ∇V, H) can call it.

Fields

value: f64

Outer criterion value at θ₀.

components: Vec<OuterGradientFdComponent>

Per-coordinate analytic-vs-FD comparison.

hessian_eigenvalues: Vec<f64>

Eigenvalues of the (symmetrized) outer Hessian at θ₀, ascending. Empty when no analytic/operator Hessian was available.

Implementations

impl OuterGradientFdAudit

pub fn analytic_block_norms(&self) -> Vec<(String, f64)>

Per-block L2 norm of the analytic gradient.

pub fn worst_component(&self) -> Option<&OuterGradientFdComponent>

Worst per-coordinate analytic−FD gap and its component.

pub fn min_abs_eigenvalue(&self) -> Option<f64>

Smallest-magnitude outer-Hessian eigenvalue (flatness proxy).

pub fn log_verdict(&self, context: &str)

Emit a single human-readable verdict block to the log.

Trait Implementations

impl Clone for OuterGradientFdAudit

fn clone(&self) -> OuterGradientFdAudit

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for OuterGradientFdAudit

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.