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// Copyright © 2023 Marvin Beckmann
//
// 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 [`PolyOverZq`] polynomial.
use super::PolyOverZq;
use crate::{
integer::Z, integer_mod_q::Zq, macros::for_others::implement_for_owned, traits::SetCoefficient,
};
use flint_sys::fmpz_mod_poly::fmpz_mod_poly_set_coeff_fmpz;
impl<Integer: Into<Z>> SetCoefficient<Integer> for PolyOverZq {
/// Sets the coefficient of a polynomial [`PolyOverZq`].
/// 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 coefficient will be set to.
///
/// # Examples
/// ```
/// use qfall_math::integer_mod_q::PolyOverZq;
/// use qfall_math::integer::Z;
/// use qfall_math::traits::*;
/// use std::str::FromStr;
///
/// let mut poly = PolyOverZq::from_str("4 0 1 2 3 mod 17").unwrap();
///
/// assert!(poly.set_coeff(4, 1000).is_ok());
/// unsafe{ poly.set_coeff_unchecked(5, 75) };
/// ```
///
/// # 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: Z = value.into();
unsafe {
fmpz_mod_poly_set_coeff_fmpz(
&mut self.poly,
index,
&value.value,
self.modulus.get_fmpz_mod_ctx_struct(),
);
}
}
}
impl SetCoefficient<&Zq> for PolyOverZq {
/// Sets the coefficient of a polynomial [`PolyOverZq`].
/// 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 from a borrowed [`Zq`].
///
/// # Examples
/// ```
/// use qfall_math::integer_mod_q::PolyOverZq;
/// use qfall_math::integer_mod_q::Zq;
/// use qfall_math::traits::*;
/// use std::str::FromStr;
///
/// let mut poly = PolyOverZq::from_str("4 0 1 2 3 mod 17").unwrap();
/// let value = Zq::from((1000, 17));
///
/// assert!(poly.set_coeff(4, &value).is_ok());
/// unsafe{ poly.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, PolyOverZq, SetCoefficient);
#[cfg(test)]
mod test_set_coeff_z {
use crate::{integer::Z, integer_mod_q::PolyOverZq, traits::SetCoefficient};
use std::str::FromStr;
/// Ensure that the negative indices return an error.
#[test]
fn set_min_negative_coeff() {
let mut poly = PolyOverZq::from_str("2 1 1 mod 11").unwrap();
assert!(poly.set_coeff(i64::MIN, 2).is_err());
assert!(poly.set_coeff(i32::MIN, 2).is_err());
assert!(poly.set_coeff(i16::MIN, 2).is_err());
assert!(poly.set_coeff(i8::MIN, 2).is_err());
}
/// Ensure that large coefficients work.
#[test]
fn set_coeff_large() {
let mut poly = PolyOverZq::from_str("2 1 1 mod 11").unwrap();
assert!(poly.set_coeff(2, i32::MAX).is_ok());
assert!(poly.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 mut poly = PolyOverZq::from_str("2 1 1 mod 11").unwrap();
assert!(poly.set_coeff(u8::MAX, 2).is_ok());
assert!(poly.set_coeff(u16::MAX, 2).is_ok());
}
/// Ensure that a general case is working.
#[test]
fn set_coeff_working() {
let mut poly = PolyOverZq::from_str("4 0 1 2 3 mod 11").unwrap();
let value = 10000;
poly.set_coeff(0, value).unwrap();
poly.set_coeff(5, value).unwrap();
assert_eq!(
PolyOverZq::from_str("6 1 1 2 3 0 1 mod 11").unwrap(),
poly
);
}
/// Ensure that the correct coefficient is set and all others are set to `0`.
#[test]
fn set_coeff_rest_zero() {
let mut poly = PolyOverZq::from_str("0 mod 11").unwrap();
poly.set_coeff(4, -10).unwrap();
assert_eq!(PolyOverZq::from_str("5 0 0 0 0 1 mod 11").unwrap(), poly);
}
/// Ensure that setting with a z works.
#[test]
fn set_coeff_z() {
let mut poly = PolyOverZq::from_str("0 mod 11").unwrap();
poly.set_coeff(4, Z::from(123)).unwrap();
assert_eq!(PolyOverZq::from_str("5 0 0 0 0 2 mod 11").unwrap(), poly);
}
}
/// we omit most of the tests for the correct values, since
/// the values itself are set with set_coeff taking in a [`Z`] value
#[cfg(test)]
mod test_set_coeff_zq {
use crate::{
integer_mod_q::{PolyOverZq, Zq},
traits::SetCoefficient,
};
use std::str::FromStr;
/// Ensure that an error is returned if the moduli do not match
#[test]
fn mismatching_moduli() {
let mut poly = PolyOverZq::from_str(&format!("4 0 1 2 3 mod {}", u64::MAX - 58)).unwrap();
let value = Zq::from((u64::MAX, u64::MAX - 57));
assert!(poly.set_coeff(4, &value).is_err());
assert_eq!(
PolyOverZq::from_str(&format!("4 0 1 2 3 mod {}", u64::MAX - 58)).unwrap(),
poly
)
}
/// Ensure that an ok is returned if the moduli not match
#[test]
fn matching_moduli() {
let mut poly = PolyOverZq::from_str(&format!("4 0 1 2 3 mod {}", u64::MAX - 58)).unwrap();
let value = Zq::from((u64::MAX, u64::MAX - 58));
assert!(poly.set_coeff(4, &value).is_ok());
assert_eq!(
PolyOverZq::from_str(&format!("5 0 1 2 3 58 mod {}", u64::MAX - 58)).unwrap(),
poly
)
}
}