Struct BlockPenaltyOp 

pub struct BlockPenaltyOp {
    pub k: usize,
    pub blocks: Vec<(usize, Array2<f64>)>,
}

Block-local penalty operator: applies per-block penalty matrices (matching ParameterBlockSpec boundaries) without materialising a full K×K dense matrix.

Each entry is (global_offset, local_matrix) where global_offset is the start of that block in the full β vector.

Fields

k: usize

Full β dimension K.

blocks: Vec<(usize, Array2<f64>)>

(global_start, local_matrix) for each atom/block.

Trait Implementations

impl BetaPenaltyOp for BlockPenaltyOp

fn dim(&self) -> usize

Full dimension K of the β vector.

fn matvec(&self, x: &[f64], y: &mut [f64])

y += P x — penalty Hessian-vector product (length K).

fn gradient(&self, beta: &[f64], out: &mut [f64])

Penalty gradient: out += P β.

fn diagonal(&self, diag: &mut [f64])

diag += diag(P) — diagonal entries used by Jacobi preconditioner.

fn block( &self, id: BetaBlockId, offsets: &[Range<usize>], out: &mut Array2<f64>, )

Add the b×b dense penalty sub-block for block id into out (row-major, block size b = offsets[id.0].len()). Used by the block-Jacobi Schur preconditioner (#287).

fn to_dense(&self) -> Array2<f64>

Materialize the full K×K dense penalty matrix (needed by Direct / SqrtBA modes that form the Schur complement explicitly).

fn fingerprint(&self, hasher: &mut Fingerprinter)

Mix the operator’s defining state into hasher for cache-validity fingerprinting. Must change whenever matvec / to_dense would change, so the factorization / evidence cache (cache_matches_system) is invalidated when the β-block content changes. Implementations hash their own compact defining data (e.g. Kronecker factors, block matrices) rather than the full K×K dense form, which would defeat the structured operator’s storage savings.

fn row_abs_sums(&self) -> Array1<f64>

Per-row absolute-value sums out[r] = Σ_c |P[r,c]|, the row contribution to the operator’s ∞-norm. The default folds to_dense(), which costs an O(K²) materialization; structured operators override this to fold their compact factors directly so the backward-error certificate’s arrow_operator_infinity_norm never builds a dense K×K matrix on the SAE LLM-border critical path (#1017). Overrides MUST agree bit-for-bit with the to_dense() row sums (verified by the cross-check tests).