Struct prio::pcp::gadgets::MeanVarUnsigned

pub struct MeanVarUnsigned<F: FieldElement> { /* fields omitted */ }

The gadget for the MeanVarUnsignedVector type. It is not designed for general use.

MeanVarUnsigned is parameterized by a positive integer bits. Its arity is 2*bits+1:

• The first bits values are interpreted as a vector r_vec.
• The next bits values are interpreted as a vector x_vec.
• The last value is interpreted as a singleton x.

The gadget is designed to output x^2 as long as x_vec is a vector comprised of 0s and 1s. It first computes w[l] = p(x_vec[l]) * r_vec[l] for each 0 <= l < bits, where p(x) = x(x-1). It then computes w = w[0] + ... + w[bits-1] and returns w + x^2.

If vec_x[l] == 1 or vec_x[l] == 0, then p(vec_x[l]) == 0; otherwise, p(vec_x[l]) != 0. The validity circuit for MeanVarUnsignedVector sets r_vec[l] = r^(l+1), where r is a uniform random field element. This is ensures that, if p(vec_x[l]) != 0 for some l, then w != 0 with high probability.

Implementations

impl<F: FieldElement> MeanVarUnsigned<F>

pub fn new(bits: usize, num_calls: usize) -> Self

Constructs a MeanVarUnsigned gadget with parameter bits. num_calls is the number of times this gadget is called by the validity circuit.

Trait Implementations

impl<F: FieldElement> Gadget<F> for MeanVarUnsigned<F>

fn call(&mut self, inp: &[F]) -> Result<F, PcpError>

Evaluates the gadget on input inp and returns the output.

fn call_poly(&mut self, outp: &mut [F], inp: &[Vec<F>]) -> Result<(), PcpError>

Evaluate the gadget on input of a sequence of polynomials. The output is written to outp.

fn arity(&self) -> usize

Returns the arity of the gadget. This is the length of inp passed to call or call_poly.

fn degree(&self) -> usize

Returns the circuit’s arithmetic degree. This determines the minimum length the outp buffer passed to call_poly.

fn as_any(&mut self) -> &mut dyn Any

This call is used to downcast a Box<dyn Gadget<F>> to a concrete type.