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// Copyright © 2023 Marcel Luca Schmidt
//
// This file is part of qFALL-math.
//
// qFALL-math is free software: you can redistribute it and/or modify it under
// the terms of the Mozilla Public License Version 2.0 as published by the
// Mozilla Foundation. See <https://mozilla.org/en-US/MPL/2.0/>.
//! Implementations to manipulate a [`PolynomialRingZq`] element.
use super::PolynomialRingZq;
use crate::{
integer::Z, integer_mod_q::Zq, macros::for_others::implement_for_owned, traits::SetCoefficient,
};
use flint_sys::fmpz_poly::fmpz_poly_set_coeff_fmpz;
impl<Integer: Into<Z>> SetCoefficient<Integer> for PolynomialRingZq {
/// Sets the coefficient of a [`PolynomialRingZq`] element.
/// We advise to use small coefficients, since already 2^32 coefficients take space
/// of roughly 34 GB. If not careful, be prepared that memory problems can occur, if
/// the index is very high.
///
/// Parameters:
/// - `index`: the index of the coefficient to set (has to be positive)
/// - `value`: the new value the index should have
///
/// # Examples
/// ```
/// use crate::qfall_math::traits::SetCoefficient;
/// use qfall_math::integer::PolyOverZ;
/// use qfall_math::integer_mod_q::{PolynomialRingZq, ModulusPolynomialRingZq};
/// use std::str::FromStr;
///
/// let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
/// let poly = PolyOverZ::from_str("3 0 1 1").unwrap();
/// let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
///
/// poly_ring.set_coeff(2, 16).unwrap();
/// unsafe{ poly_ring.set_coeff_unchecked(5, 5) };
/// ```
///
/// # Safety
/// To use this function safely, make sure that the selected index
/// is greater or equal than `0` and that the provided value has
/// the same base so that they have a matching base.
unsafe fn set_coeff_unchecked(&mut self, index: i64, value: Integer) {
let value = value.into();
unsafe {
fmpz_poly_set_coeff_fmpz(&mut self.poly.poly, index, &value.value);
};
self.reduce();
}
}
impl SetCoefficient<&Zq> for PolynomialRingZq {
/// Sets the coefficient of a [`PolynomialRingZq`] element.
/// We advise to use small coefficients, since already 2^32 coefficients take space
/// of roughly 34 GB. If not careful, be prepared that memory problems can occur, if
/// the index is very high.
///
/// This function does not check if the modulus of the polynomial and the value match.
///
/// Parameters:
/// - `index`: the index of the coefficient to set (has to be positive)
/// - `value`: the new value the index should have
///
/// # Examples
/// ```
/// use crate::qfall_math::traits::SetCoefficient;
/// use qfall_math::integer::PolyOverZ;
/// use qfall_math::integer_mod_q::{PolynomialRingZq, ModulusPolynomialRingZq};
/// use qfall_math::integer_mod_q::Zq;
/// use std::str::FromStr;
///
/// let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
/// let poly = PolyOverZ::from_str("3 0 1 1").unwrap();
/// let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
/// let value = Zq::from((1000, 17));
///
/// poly_ring.set_coeff(2, &value).unwrap();
/// unsafe{ poly_ring.set_coeff_unchecked(5, &value) };
/// ```
///
/// # Safety
/// To use this function safely, make sure that the selected index
/// is greater or equal than `0` and that the provided value has
/// the same base so that they have a matching base.
unsafe fn set_coeff_unchecked(&mut self, index: i64, value: &Zq) {
unsafe { self.set_coeff_unchecked(index, &value.value) };
}
}
implement_for_owned!(Zq, PolynomialRingZq, SetCoefficient);
#[cfg(test)]
mod test_set_coeff {
use crate::{
integer::{PolyOverZ, Z},
integer_mod_q::{ModulusPolynomialRingZq, PolynomialRingZq, Zq},
traits::SetCoefficient,
};
use std::str::FromStr;
/// Ensure that setting is available for other types.
#[test]
fn availability() {
let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
let poly = PolyOverZ::from_str("3 0 1 1").unwrap();
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
poly_ring.set_coeff(1, 3u64).unwrap();
poly_ring.set_coeff(1, 3u32).unwrap();
poly_ring.set_coeff(1, 3u16).unwrap();
poly_ring.set_coeff(1, 3u8).unwrap();
poly_ring.set_coeff(1, 3i64).unwrap();
poly_ring.set_coeff(1, 3i32).unwrap();
poly_ring.set_coeff(1, 3i16).unwrap();
poly_ring.set_coeff(1, 3i8).unwrap();
poly_ring.set_coeff(1, Z::from(3)).unwrap();
poly_ring.set_coeff(1, &Z::from(3)).unwrap();
poly_ring.set_coeff(1, &Zq::from((3, 17))).unwrap();
}
/// Ensure that large coefficients work.
#[test]
fn set_coeff_large() {
let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
let poly = PolyOverZ::from_str("3 0 1 1").unwrap();
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
assert!(poly_ring.set_coeff(2, i32::MAX).is_ok());
assert!(poly_ring.set_coeff(2, i64::MAX).is_ok());
}
/// Ensure that the max of [`u8`] and [`u16`] works as an index.
#[test]
fn set_index_large() {
let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
let poly = PolyOverZ::from_str("3 0 1 1").unwrap();
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
assert!(poly_ring.set_coeff(u8::MAX, 2).is_ok());
assert!(poly_ring.set_coeff(u16::MAX, 2).is_ok());
}
/// Ensure that a general case is working.
#[test]
fn set_coeff_working() {
let modulus = ModulusPolynomialRingZq::from_str("5 1 0 0 1 1 mod 17").unwrap();
let poly = PolyOverZ::from_str("3 0 2 1").unwrap();
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
let value = 10000;
poly_ring.set_coeff(0, value).unwrap();
poly_ring.set_coeff(2, value).unwrap();
let cmp_poly = PolyOverZ::from_str("3 10000 2 10000").unwrap();
let cmp_poly_ring = PolynomialRingZq::from((&cmp_poly, &modulus));
assert_eq!(cmp_poly_ring, poly_ring);
}
/// Ensure that the set polynomial is reduced correctly.
#[test]
fn set_reduce() {
let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
let poly = PolyOverZ::from(1);
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
poly_ring.set_coeff(3, 1).unwrap();
let cmp_poly = PolyOverZ::from(0);
let cmp_poly_ring = PolynomialRingZq::from((&cmp_poly, &modulus));
assert_eq!(cmp_poly_ring, poly_ring);
}
/// Ensure that the correct coefficient is set and all others are set to `0`.
#[test]
fn set_coeff_rest_zero() {
let modulus = ModulusPolynomialRingZq::from_str("7 10 12 0 0 10 0 1 mod 17").unwrap();
let poly = PolyOverZ::from_str("2 0 2").unwrap();
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
poly_ring.set_coeff(5, 10).unwrap();
let cmp_poly = PolyOverZ::from_str("6 0 2 0 0 0 10").unwrap();
let cmp_poly_ring = PolynomialRingZq::from((&cmp_poly, &modulus));
assert_eq!(cmp_poly_ring, poly_ring);
}
/// Ensure that the negative indices return an error.
#[test]
fn set_negative_index() {
let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
let poly = PolyOverZ::from_str("3 0 1 1").unwrap();
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
assert!(poly_ring.set_coeff(-1, 2).is_err());
assert!(poly_ring.set_coeff(i64::MIN, 2).is_err());
assert!(poly_ring.set_coeff(i32::MIN, 2).is_err());
assert!(poly_ring.set_coeff(i16::MIN, 2).is_err());
assert!(poly_ring.set_coeff(i8::MIN, 2).is_err());
}
/// Ensure that a different base returns an error.
#[test]
fn different_base() {
let modulus = ModulusPolynomialRingZq::from_str("4 1 0 0 1 mod 17").unwrap();
let poly = PolyOverZ::from_str("3 0 1 1").unwrap();
let mut poly_ring = PolynomialRingZq::from((&poly, &modulus));
let value = Zq::from((13, 18));
assert!(poly_ring.set_coeff(1, &value).is_err());
}
}