Struct believer::parity_check_matrix::ParityCheckMatrix

pub struct ParityCheckMatrix { /* fields omitted */ }

A sparse implementation of a parity check matrix.

Methods

impl ParityCheckMatrix

pub fn new() -> Self

Creates an empty parity check matrix. That is, a parity check with 0 bit and 0 check.

Example

use believer::ParityCheckMatrix;
let matrix = ParityCheckMatrix::new();

pub fn with_n_bits(n_bits: usize) -> Self

Creates a new ParityCheckMatrix with n_bits and no checks.

Example

use believer::ParityCheckMatrix;
let matrix = ParityCheckMatrix::with_n_bits(5);

pub fn with_checks(self, checks: Vec<Check>) -> Self

Set the checks of self consuming checks.

Panic

Panics if some checks are out of bounds. That is, if they are connected to a bit that is greater or equal than self.get_n_bits().

Example

use believer::ParityCheckMatrix;
let checks = vec![vec![0, 1], vec![1, 2]];
let mut matrix = ParityCheckMatrix::with_n_bits(3).with_checks(checks);

pub fn identity_with_n_bits(n_bits: usize) -> ParityCheckMatrix

Creates the n_bits identity matrix.

Example

use believer::ParityCheckMatrix;

let matrix = ParityCheckMatrix::identity_with_n_bits(3);

let identity_checks = vec![vec![0], vec![1], vec![2]];
let identity_matrix = ParityCheckMatrix::with_n_bits(3)
    .with_checks(identity_checks);

assert_eq!(matrix, identity_matrix);

pub fn get_n_bits(&self) -> usize

Returns the number of bits in self.

pub fn get_n_checks(&self) -> usize

Returns the number of checks in self.

pub fn get_n_edges(&self) -> usize

Returns the number of edges in self.

pub fn get_bit_degrees(&self) -> Vec<usize>

Returns the degree of each bit in self.

Example

use believer::ParityCheckMatrix;

let checks = vec![vec![0, 1, 2, 5], vec![1, 3, 4], vec![2, 4, 5], vec![0, 5]];
let matrix = ParityCheckMatrix::with_n_bits(7).with_checks(checks);
assert_eq!(matrix.get_bit_degrees(), vec![2, 2, 2, 1, 2, 3, 0]);

pub fn get_check_degrees(&self) -> Vec<usize>

Returns the degree of each check in self.

Example

use believer::ParityCheckMatrix;

let checks = vec![vec![0, 1, 2, 5], vec![1, 3, 4], vec![2, 4, 5], vec![0, 5]];
let matrix = ParityCheckMatrix::with_n_bits(7).with_checks(checks);
assert_eq!(matrix.get_check_degrees(), vec![4, 3, 3, 2]);

pub fn get_check(&self, check: usize) -> Option<CheckView>

Returns Some view over the given check in self. Returns None if check is out of bound.

Example

use believer::ParityCheckMatrix;

let checks = vec![vec![0, 1], vec![1, 2]];

let parity_check = ParityCheckMatrix::with_n_bits(3).with_checks(checks);

let check = parity_check.get_check(0).unwrap();
assert_eq!(check.as_ref(), &[0, 1]);

let check = parity_check.get_check(1).unwrap();
assert_eq!(check.as_ref(), &[1, 2]);

assert!(parity_check.get_check(2).is_none());

pub fn get_syndrome_of(&self, message: &[GF2]) -> Vec<GF2>

Computes the syndrome of a given message.

Example

use believer::{GF2, ParityCheckMatrix};

let checks = vec![vec![0, 1], vec![1, 2]];
let parity_check = ParityCheckMatrix::with_n_bits(3).with_checks(checks);

let message = vec![GF2::B0, GF2::B1, GF2::B1];

assert_eq!(parity_check.get_syndrome_of(&message), vec![GF2::B1, GF2::B0]);

pub fn get_rank(&self) -> usize

Computes the rank of self.

Example

use believer::ParityCheckMatrix;

let checks = vec![vec![0, 1], vec![1, 2], vec![0, 2]];
let parity_check = ParityCheckMatrix::with_n_bits(3).with_checks(checks);

assert_eq!(parity_check.get_rank(), 2);

pub fn get_transposed_matrix(&self) -> Self

Gets the transposed version of self by swapping the bits with the checks.

Example

use believer::ParityCheckMatrix;

let checks = vec![vec![0, 1, 2], vec![1, 3], vec![0, 2, 3]];
let matrix = ParityCheckMatrix::with_n_bits(4).with_checks(checks);

let transposed_matrix = matrix.get_transposed_matrix();

let expected_checks = vec![vec![0, 2], vec![0, 1], vec![0, 2], vec![1, 2]];
let expected_matrix = ParityCheckMatrix::with_n_bits(3).with_checks(expected_checks);

assert_eq!(transposed_matrix, expected_matrix);

pub fn get_horizontal_concat_with(
    &self,
    other: &ParityCheckMatrix
) -> ParityCheckMatrix

Returns the horizontal concatenation of self with other.

Example

use believer::ParityCheckMatrix;
let left_matrix = ParityCheckMatrix::with_n_bits(3)
    .with_checks(vec![vec![0, 1], vec![1, 2]]);
let right_matrix = ParityCheckMatrix::with_n_bits(4)
    .with_checks(vec![vec![1, 2, 3], vec![0, 1], vec![2, 3]]);

let concatened = left_matrix.get_horizontal_concat_with(&right_matrix);

let expected = ParityCheckMatrix::with_n_bits(7)
    .with_checks(vec![vec![0, 1, 4, 5, 6], vec![1, 2, 3, 4], vec![5, 6]]);

assert_eq!(concatened, expected);

pub fn get_diagonal_concat_with(
    &self,
    other: &ParityCheckMatrix
) -> ParityCheckMatrix

Returns the diagonal concatenation of self with other.

Example

use believer::ParityCheckMatrix;
let left_matrix = ParityCheckMatrix::with_n_bits(3)
    .with_checks(vec![vec![0, 1], vec![1, 2]]);
let right_matrix = ParityCheckMatrix::with_n_bits(4)
    .with_checks(vec![vec![1, 2, 3], vec![0, 1], vec![2, 3]]);

let concatened = left_matrix.get_diagonal_concat_with(&right_matrix);

let expected = ParityCheckMatrix::with_n_bits(7)
    .with_checks(vec![vec![0, 1], vec![1, 2], vec![4, 5, 6], vec![3, 4], vec![5, 6]]);

assert_eq!(concatened, expected);

Important traits for ChecksIter<'a>

impl<'a> Iterator for ChecksIter<'a> type Item = CheckView<'a>;

pub fn checks_iter(&self) -> ChecksIter

Returns an iterator that yields a slice for each check of self.

Example

use believer::ParityCheckMatrix;

let parity_check = ParityCheckMatrix::with_n_bits(3)
    .with_checks(vec![vec![0, 1], vec![1, 2]]);

let mut iter = parity_check.checks_iter();

assert_eq!(iter.next(), parity_check.get_check(0));
assert_eq!(iter.next(), parity_check.get_check(1));
assert_eq!(iter.next(), None);

Important traits for EdgesIter<'a>

impl<'a> Iterator for EdgesIter<'a> type Item = (usize, usize);

pub fn edges_iter(&self) -> EdgesIter

An iterators over all edges in self ordered by check first.

Example

let parity_check = ParityCheckMatrix::with_n_bits(3)
    .with_checks(vec![vec![0, 1], vec![1, 2]]);

let mut iter = parity_check.edges_iter();

assert_eq!(iter.next(), Some((0, 0)));
assert_eq!(iter.next(), Some((0, 1)));
assert_eq!(iter.next(), Some((1, 1)));
assert_eq!(iter.next(), Some((1, 2)));
assert_eq!(iter.next(), None);

pub fn has_codeword(&self, message: &[GF2]) -> bool

Checks if a given message is a codeword of self.

Example

use believer::{GF2, ParityCheckMatrix};
let parity_check = ParityCheckMatrix::with_n_bits(3)
    .with_checks(vec![vec![0, 1], vec![1, 2]]);
let message = vec![GF2::B0, GF2::B1, GF2::B1];
let codeword = vec![GF2::B0; 3];

assert_eq!(parity_check.has_codeword(&message), false);
assert_eq!(parity_check.has_codeword(&codeword), true);

pub fn keep(&self, bits: &[usize]) -> Self

Returns a truncated parity check matrix with only the column of the given bits.

Example

use believer::ParityCheckMatrix;
let checks = ParityCheckMatrix::with_n_bits(5).with_checks(vec![
    vec![0, 1, 2],
    vec![2, 3, 4],
    vec![0, 2, 4],
    vec![1, 3],
]);

let truncated_checks = ParityCheckMatrix::with_n_bits(5).with_checks(vec![
    vec![0, 1],
    vec![4],
    vec![0, 4],
    vec![1],
]);

assert_eq!(checks.keep(&[0, 1, 4]), truncated_checks);

pub fn without(&self, bits: &[usize]) -> Self

Returns a truncated parity check matrix where the column of the given bits are remove.

Example

let checks = ParityCheckMatrix::with_n_bits(5).with_checks(vec![
    vec![0, 1, 2],
    vec![2, 3, 4],
    vec![0, 2, 4],
    vec![1, 3],
]);

let truncated_checks = ParityCheckMatrix::with_n_bits(5).with_checks(vec![
    vec![1],
    vec![3, 4],
    vec![4],
    vec![1, 3],
]);

assert_eq!(checks.without(&[0, 2]), truncated_checks);

pub fn gbc(&self, b: &ParityCheckMatrix) -> ParityCheckMatrix

pub fn permu_matrix(l: usize) -> ParityCheckMatrix

pub fn circulant_down(indices: &Vec<usize>, l: usize) -> ParityCheckMatrix

pub fn circulant_right(indices: &Vec<usize>, l: usize) -> ParityCheckMatrix

Trait Implementations

impl Clone for ParityCheckMatrix

fn clone(&self) -> ParityCheckMatrix

Returns a copy of the value.

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

Performs copy-assignment from source.

impl PartialEq<ParityCheckMatrix> for ParityCheckMatrix

fn eq(&self, other: &ParityCheckMatrix) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &ParityCheckMatrix) -> bool

This method tests for !=.

impl Debug for ParityCheckMatrix

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

Formats the value using the given formatter.

impl Display for ParityCheckMatrix

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

Formats the value using the given formatter.

impl StructuralPartialEq for ParityCheckMatrix