Struct EriScratch 

pub struct EriScratch { /* private fields */ }

Reusable scratch arena for the OS/HGP ERI engine.

Holds the engine’s working buffers so they are allocated once and reused across shell quartets, instead of a fresh heap allocation per quartet inside the O(n⁴) shell loop. All buffers are plain Vec<f64> grown on demand in safe Rust (#![forbid(unsafe_code)] holds); there is no shared mutable state, so each thread uses its own instance — the thread-local default behind coulomb_shell_into, or one passed explicitly to coulomb_shell_into_scratch (the &mut makes cross-thread sharing a compile error).

Memory-correctness. c_ef is an accumulator and is zeroed per quartet. The VRR levels and HRR bra/layer buffers are fully overwritten in the region they are later read, so they need no functional zeroing — but in debug builds levels and bra are NaN-filled per quartet, so any accidental out-of-range read (e.g. outside the VRR m-triangle) poisons the output and trips the tests rather than silently reading a stale value from a previous quartet. Results are therefore independent of evaluation order and of arena reuse (asserted by tests/arena.rs).

Implementations

impl EriScratch

pub fn new() -> Self

A fresh, empty arena; it grows to fit on first use.

pub fn resident_f64(&self) -> usize

Total f64 elements currently held across all buffers — the resident working set, for memory reporting/tests.

pub fn largest_buffer_f64(&self) -> usize

Largest single buffer (f64 elements). Demonstrates the former ~41 MB monolithic VRR [e0|f0]^(m) table is no longer resident: the m-marching window keeps only 3·max_k[n_cart(k)·slab_k].

Trait Implementations

impl Clone for EriScratch

fn clone(&self) -> EriScratch

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for EriScratch

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

Formats the value using the given formatter.

impl Default for EriScratch

fn default() -> EriScratch

Returns the “default value” for a type.