Struct Gf2Hash 

pub struct Gf2Hash<const W: usize> { /* private fields */ }

The GF(2)-linear hash h(v) = H·v from a Pauli key v = (x, z) to a bucket index, for a dense random H drawn from a seed.

Linearity gives h(v ⊕ d) = h(v) ⊕ h(d), so a channel’s output buckets are predictable from its input buckets. The active rows are a prefix of one fixed matrix, so a refine splits every bucket in two by one row parity with the within-bucket order inherited, and a coarsen merges bucket pairs; neither needs a sort to keep the PauliSum invariant.

Implementations

impl<const W: usize> Gf2Hash<W>

pub fn new(num_qubits: usize, bits: u8, seed: u64) -> Self

Build a hash over num_qubits qubits with bits active bucket bits.

The rows are a function of (num_qubits, seed) alone, independent of W.

Panics

Panics if bits > B_MAX_BITS, or in debug builds if num_qubits > 64 · W.

pub fn bits(&self) -> u8

Number of active bucket bits.

pub fn num_buckets(&self) -> usize

Number of buckets, 1 << bits().

pub fn seed(&self) -> u64

The seed the rows were generated from.

pub fn num_qubits(&self) -> usize

The qubit count the rows were masked against.

pub fn bucket_of(&self, x: &[u64; W], z: &[u64; W]) -> u32

h(v) for a key given as separate x and z words.

pub fn refine(&mut self)

Double the bucket count: B → 2B.

Panics

Panics if already at B_MAX_BITS.

pub fn coarsen(&mut self)

Halve the bucket count: B → B/2, merging buckets b and b + B/2.

Panics

Panics if already at a single bucket.

Trait Implementations

impl<const W: usize> Clone for Gf2Hash<W>

fn clone(&self) -> Gf2Hash<W>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<const W: usize> Debug for Gf2Hash<W>

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

Formats the value using the given formatter.