Struct Poly 

pub struct Poly<C>(/* private fields */);

A polynomial that is using a scalar for the variable x and a generic element for the coefficients.

The coefficients must be able to multiply the type of the variable, which is always a scalar.

Implementations

impl<C> Poly<C>

pub fn from(c: Vec<C>) -> Self

Creates a new polynomial from the given coefficients.

pub fn constant(&self) -> &C

Returns the constant term of the polynomial.

pub fn degree(&self) -> u32

Returns the degree of the polynomial

pub fn required(&self) -> u32

Returns the number of required shares to reconstruct the polynomial.

This will be the threshold

impl<C: Element> Poly<C>

pub fn commit(commits: Poly<Scalar>) -> Self

Commits the scalar polynomial to the group and returns a polynomial over the group.

This is done by multiplying each coefficient of the polynomial with the group’s generator.

pub fn zero() -> Self

Returns a zero polynomial.

pub fn get(&self, i: u32) -> C

Returns the given coefficient at the requested index.

It panics if the index is out of range.

pub fn set(&mut self, index: u32, value: C)

Set the given element at the specified index.

It panics if the index is out of range.

pub fn add(&mut self, other: &Self)

Performs polynomial addition in place.

pub fn evaluate(&self, index: u32) -> Eval<C>

Evaluates the polynomial at the specified index (provided value offset by 1).

pub fn recover_with_weights<'a, I>( weights: &BTreeMap<u32, Weight>, evals: I, ) -> Result<C, Error>

where C: 'a, I: IntoIterator<Item = &'a Eval<C>>,

Recovers the constant term of a polynomial of degree less than t using t evaluations of the polynomial and precomputed Barycentric Weights.

This function uses Lagrange interpolation to compute the constant term (i.e., the value of the polynomial at x=0) given at least t distinct evaluations of the polynomial. Each evaluation is assumed to have a unique index, which is mapped to a unique x-value as x = index + 1.

References

This implementation is based on J.-P. Berrut and L. N. Trefethen, “Barycentric Lagrange Interpolation,” SIAM Rev., vol. 46, no. 3, pp. 501–517, 2004.

Warning

This function assumes that each evaluation has a unique index. If there are duplicate indices, the function may fail with an error when attempting to compute the inverse of zero.

pub fn recover<'a, I>(t: u32, evals: I) -> Result<C, Error>

where C: 'a, I: IntoIterator<Item = &'a Eval<C>>,

Recovers the constant term of a polynomial of degree less than t using at least t evaluations of the polynomial.

This function uses Lagrange interpolation to compute the constant term (i.e., the value of the polynomial at x=0) given at least t distinct evaluations of the polynomial. Each evaluation is assumed to have a unique index, which is mapped to a unique x-value as x = index + 1.

References

This implementation is based on J.-P. Berrut and L. N. Trefethen, “Barycentric Lagrange Interpolation,” SIAM Rev., vol. 46, no. 3, pp. 501–517, 2004.

Warning

This function assumes that each evaluation has a unique index. If there are duplicate indices, the function may fail with an error when attempting to compute the inverse of zero.

Trait Implementations

impl<C: Clone> Clone for Poly<C>

fn clone(&self) -> Poly<C>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<C: Debug> Debug for Poly<C>

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

Formats the value using the given formatter.

impl<C: Element> EncodeSize for Poly<C>

fn encode_size(&self) -> usize

Returns the encoded size of this value (in bytes).

impl<C: PartialEq> PartialEq for Poly<C>

fn eq(&self, other: &Poly<C>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl<C: Element> Read for Poly<C>

type Cfg = usize

The Cfg type parameter allows passing configuration during the read process. This is crucial for safely decoding untrusted data, for example, by providing size limits for collections or strings.

fn read_cfg( buf: &mut impl Buf, expected: &Self::Cfg, ) -> Result<Self, CodecError>

Reads a value from the buffer using the provided configuration cfg.

impl<C: Element> Write for Poly<C>

fn write(&self, buf: &mut impl BufMut)

Writes the binary representation of self to the provided buffer buf.

impl<C: Eq> Eq for Poly<C>

impl<C> StructuralPartialEq for Poly<C>