1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150

// Copyright (C) 2019-2021 Aleo Systems Inc.
// This file is part of the snarkVM library.

// The snarkVM library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The snarkVM library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the snarkVM library. If not, see <https://www.gnu.org/licenses/>.

//! A polynomial represented in evaluations form.

use crate::fft::{DensePolynomial, EvaluationDomain};
use snarkvm_fields::PrimeField;
use snarkvm_utilities::{errors::SerializationError, serialize::*};

use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Sub, SubAssign};

/// Stores a polynomial in evaluation form.
#[derive(Clone, PartialEq, Eq, Hash, Debug, CanonicalSerialize, CanonicalDeserialize)]
pub struct Evaluations<F: PrimeField> {
    /// The evaluations of a polynomial over the domain `D`
    pub evaluations: Vec<F>,
    #[doc(hidden)]
    domain: EvaluationDomain<F>,
}

impl<F: PrimeField> Evaluations<F> {
    /// Construct `Self` from evaluations and a domain.
    pub fn from_vec_and_domain(evaluations: Vec<F>, domain: EvaluationDomain<F>) -> Self {
        Self { evaluations, domain }
    }

    /// Interpolate a polynomial from a list of evaluations
    pub fn interpolate_by_ref(&self) -> DensePolynomial<F> {
        DensePolynomial::from_coefficients_vec(self.domain.ifft(&self.evaluations))
    }

    /// Interpolate a polynomial from a list of evaluations
    pub fn interpolate(self) -> DensePolynomial<F> {
        let Self {
            evaluations: mut evals,
            domain,
        } = self;
        domain.ifft_in_place(&mut evals);
        DensePolynomial::from_coefficients_vec(evals)
    }
}

impl<F: PrimeField> std::ops::Index<usize> for Evaluations<F> {
    type Output = F;

    fn index(&self, index: usize) -> &F {
        &self.evaluations[index]
    }
}

impl<'a, 'b, F: PrimeField> Mul<&'a Evaluations<F>> for &'b Evaluations<F> {
    type Output = Evaluations<F>;

    #[inline]
    fn mul(self, other: &'a Evaluations<F>) -> Evaluations<F> {
        let mut result = self.clone();
        result *= other;
        result
    }
}

impl<'a, F: PrimeField> MulAssign<&'a Evaluations<F>> for Evaluations<F> {
    #[inline]
    fn mul_assign(&mut self, other: &'a Evaluations<F>) {
        assert_eq!(self.domain, other.domain, "domains are unequal");
        self.evaluations
            .iter_mut()
            .zip(&other.evaluations)
            .for_each(|(a, b)| *a *= b);
    }
}

impl<'a, 'b, F: PrimeField> Add<&'a Evaluations<F>> for &'b Evaluations<F> {
    type Output = Evaluations<F>;

    #[inline]
    fn add(self, other: &'a Evaluations<F>) -> Evaluations<F> {
        let mut result = self.clone();
        result += other;
        result
    }
}

impl<'a, F: PrimeField> AddAssign<&'a Evaluations<F>> for Evaluations<F> {
    #[inline]
    fn add_assign(&mut self, other: &'a Evaluations<F>) {
        assert_eq!(self.domain, other.domain, "domains are unequal");
        self.evaluations
            .iter_mut()
            .zip(&other.evaluations)
            .for_each(|(a, b)| *a += b);
    }
}

impl<'a, 'b, F: PrimeField> Sub<&'a Evaluations<F>> for &'b Evaluations<F> {
    type Output = Evaluations<F>;

    #[inline]
    fn sub(self, other: &'a Evaluations<F>) -> Evaluations<F> {
        let mut result = self.clone();
        result -= other;
        result
    }
}

impl<'a, F: PrimeField> SubAssign<&'a Evaluations<F>> for Evaluations<F> {
    #[inline]
    fn sub_assign(&mut self, other: &'a Evaluations<F>) {
        assert_eq!(self.domain, other.domain, "domains are unequal");
        self.evaluations
            .iter_mut()
            .zip(&other.evaluations)
            .for_each(|(a, b)| *a -= b);
    }
}

impl<'a, 'b, F: PrimeField> Div<&'a Evaluations<F>> for &'b Evaluations<F> {
    type Output = Evaluations<F>;

    #[inline]
    fn div(self, other: &'a Evaluations<F>) -> Evaluations<F> {
        let mut result = self.clone();
        result /= other;
        result
    }
}

impl<'a, F: PrimeField> DivAssign<&'a Evaluations<F>> for Evaluations<F> {
    #[inline]
    fn div_assign(&mut self, other: &'a Evaluations<F>) {
        assert_eq!(self.domain, other.domain, "domains are unequal");
        self.evaluations
            .iter_mut()
            .zip(&other.evaluations)
            .for_each(|(a, b)| *a /= b);
    }
}