Struct winter_verifier::BoundaryConstraint

pub struct BoundaryConstraint<B, E> where
    E: FieldElement<BaseField = B>,
    B: StarkField,  { /* fields omitted */ }

The numerator portion of a boundary constraint.

A boundary constraint is described by a rational function $\frac{f(x) - b(x)}{z(x)}$, where:

• $f(x)$ is a trace polynomial for the register against which the constraint is placed.
• $b(b)$ is the value polynomial for this constraint.
• $z(x)$ is the constraint divisor polynomial.

In addition to the value polynomial, a BoundaryConstraint also contains info needed to evaluate the constraint and to compose constraint evaluations with other constraints (i.e., constraint composition coefficients).

BoundaryConstraints cannot be instantiated directly, they are created internally from Assertions.

Implementations

impl<B, E> BoundaryConstraint<B, E> where
    E: FieldElement<BaseField = B>,
    B: StarkField, 

pub fn register(&self) -> usize

Returns index of the register against which this constraint applies.

pub fn poly(&self) -> &[B]

Returns a value polynomial for this constraint.

pub fn poly_offset(&self) -> (usize, B)

Returns offset by which we need to shift the domain before evaluating this constraint.

The offset is returned as a tuple describing both, the number of steps by which the domain needs to be shifted, and field element by which a domain element needs to be multiplied to achieve the desired shift.

pub fn cc(&self) -> &(E, E)

Returns composition coefficients for this constraint.

pub fn evaluate_at(&self, x: E, trace_value: E) -> E

Evaluates this constraint at the specified point x.

The constraint is evaluated by computing $f(x) - b(x)$, where:

• $f$ is a trace polynomial for the register against which the constraint is placed.
• $f(x)$ = trace_value
• $b$ is the value polynomial for this constraint.

For boundary constraints derived from single and periodic assertions, $b(x)$ is a constant.

Trait Implementations

impl<B, E> Clone for BoundaryConstraint<B, E> where
    E: Clone + FieldElement<BaseField = B>,
    B: Clone + StarkField, 

pub fn clone(&self) -> BoundaryConstraint<B, E>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<B, E> Debug for BoundaryConstraint<B, E> where
    E: Debug + FieldElement<BaseField = B>,
    B: Debug + StarkField, 

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

Formats the value using the given formatter.

impl<B, E> PartialEq<BoundaryConstraint<B, E>> for BoundaryConstraint<B, E> where
    E: PartialEq<E> + FieldElement<BaseField = B>,
    B: PartialEq<B> + StarkField, 

pub fn eq(&self, other: &BoundaryConstraint<B, E>) -> bool

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

pub fn ne(&self, other: &BoundaryConstraint<B, E>) -> bool

This method tests for !=.

impl<B, E> Eq for BoundaryConstraint<B, E> where
    E: Eq + FieldElement<BaseField = B>,
    B: Eq + StarkField, 

impl<B, E> StructuralEq for BoundaryConstraint<B, E> where
    E: FieldElement<BaseField = B>,
    B: StarkField, 

impl<B, E> StructuralPartialEq for BoundaryConstraint<B, E> where
    E: FieldElement<BaseField = B>,
    B: StarkField,