M arith/src/ring.rs → arith/src/ring.rs

@@ -1,7 +1,7 @@
 use rand::{distributions::Distribution, Rng};
 use std::fmt::Debug;
 use std::iter::Sum;
-use std::ops::{Add, AddAssign, Mul, Sub, SubAssign};
+use std::ops::{Add, AddAssign, Mul, Neg, Sub, SubAssign};
 
 /// Represents a ring element. Currently implemented by ring_nq.rs#Rq and
 /// ring_torus.rs#Tn. Is not a 'pure algebraic ring', but more a custom trait
@@ -17,6 +17,7 @@ + SubAssign
     + Mul<Output = Self> // internal product
     + Mul<u64, Output = Self> // scalar mul, external product
     + Mul<Self::C, Output = Self>
+    + Neg<Output = Self>
     + PartialEq
     + Debug
     + Clone

M arith/src/ring_torus.rs → arith/src/ring_torus.rs

@@ -10,7 +10,7 @@
 use rand::{distributions::Distribution, Rng};
 use std::array;
 use std::iter::Sum;
-use std::ops::{Add, AddAssign, Mul, Sub, SubAssign};
+use std::ops::{Add, AddAssign, Mul, Neg, Sub, SubAssign};
 
 use crate::{ring::Ring, torus::T64, Rq, Zq};
 
@@ -34,7 +34,7 @@ Self(array::from_fn(|_| T64::zero()))
     }
 
     fn rand(mut rng: impl Rng, dist: impl Distribution<f64>) -> Self {
-        Self(array::from_fn(|_| T64::rand_f64(&mut rng, &dist)))
+        Self(array::from_fn(|_| T64::rand(&mut rng, &dist)))
     }
 
     fn from_vec(coeffs: Vec<Self::C>) -> Self {
@@ -149,6 +149,14 @@ fn sub_assign(&mut self, rhs: Self) {
         for i in 0..N {
             self.0[i] -= rhs.0[i];
         }
+    }
+}
+
+impl<const N: usize> Neg for Tn<N> {
+    type Output = Self;
+
+    fn neg(self) -> Self::Output {
+        Tn(array::from_fn(|i| -self.0[i]))
     }
 }
 

M arith/src/torus.rs → arith/src/torus.rs

@@ -4,37 +4,65 @@ iter::Sum,
     ops::{Add, AddAssign, Mul, MulAssign, Neg, Sub, SubAssign},
 };
 
+use crate::ring::Ring;
+
 /// Let 𝕋 = ℝ/ℤ, where 𝕋 is a ℤ-module, with homogeneous external product.
 /// Let 𝕋q
 /// T64 is 𝕋q with q=2^Ω, with Ω=64. We identify 𝕋q=(1/q)ℤ/ℤ ≈ ℤq.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub struct T64(pub u64);
 
-impl T64 {
-    pub fn zero() -> Self {
+// implement the `Ring` trait for T64, so that it can be used where we would use
+// `Tn<1>`.
+impl Ring for T64 {
+    type C = T64;
+    const Q: u64 = u64::MAX; // WIP
+    const N: usize = 1;
+
+    fn coeffs(&self) -> Vec<T64> {
+        vec![self.clone()]
+    }
+    fn zero() -> Self {
         Self(0u64)
     }
-    pub fn rand(mut rng: impl Rng, dist: impl Distribution<u64>) -> Self {
-        let r: u64 = dist.sample(&mut rng);
-        Self(r)
-    }
-    pub fn rand_f64(mut rng: impl Rng, dist: impl Distribution<f64>) -> Self {
+    fn rand(mut rng: impl Rng, dist: impl Distribution<f64>) -> Self {
         let r: f64 = dist.sample(&mut rng);
         Self(r.round() as u64)
+    }
+    fn from_vec(coeffs: Vec<Self::C>) -> Self {
+        assert_eq!(coeffs.len(), 1);
+        coeffs[0]
     }
 
+    // TODO rm beta & l from inputs, make it always beta=2,l=64.
     /// Note: only beta=2 and l=64 is supported.
-    pub fn decompose(&self, beta: u32, l: u32) -> Vec<Self> {
+    fn decompose(&self, beta: u32, l: u32) -> Vec<Self> {
         assert_eq!(beta, 2u32); // only beta=2 supported
-        assert_eq!(l, 64u32); // only l=64 supported
+                                // assert_eq!(l, 64u32); // only l=64 supported
 
-        (0..64)
+        // (0..64)
+        (0..l)
             .rev()
             .map(|i| T64(((self.0 >> i) & 1) as u64))
             .collect()
     }
-    pub fn mod_switch<const Q2: u64>(&self) -> T64 {
+    fn remodule<const P: u64>(&self) -> T64 {
+        todo!()
+    }
+
+    fn mod_switch<const Q2: u64>(&self) -> T64 {
         todo!()
+    }
+
+    fn mul_div_round(&self, num: u64, den: u64) -> Self {
+        T64(((num as f64 * self.0 as f64) / den as f64).round() as u64)
+    }
+}
+
+impl T64 {
+    pub fn rand_u64(mut rng: impl Rng, dist: impl Distribution<u64>) -> Self {
+        let r: u64 = dist.sample(&mut rng);
+        Self(r)
     }
 }
 
@@ -99,6 +127,9 @@ impl Mul<u64> for T64 {
     type Output = Self;
 
     fn mul(self, s: u64) -> Self {
+        if self.0 == 0 {
+            return Self(0);
+        }
         Self(self.0.wrapping_mul(s))
     }
 }

M arith/src/tuple_ring.rs → arith/src/tuple_ring.rs

@@ -8,7 +8,7 @@ use rand_distr::{Normal, Uniform};
 use std::iter::Sum;
 use std::{
     array,
-    ops::{Add, Mul, Sub},
+    ops::{Add, Mul, Neg, Sub},
 };
 
 use crate::Ring;
@@ -34,6 +34,12 @@ // returns the decomposition of each polynomial element
     pub fn decompose(&self, beta: u32, l: u32) -> Vec<Self> {
         unimplemented!()
         // self.0.iter().map(|r| r.decompose(beta, l)).collect() // this is Vec<Vec<Vec<R::C>>>
+    }
+}
+
+impl<R: Ring, const K: usize> TR<R, K> {
+    pub fn iter(&self) -> std::slice::Iter<R> {
+        self.0.iter()
     }
 }
 
@@ -52,6 +58,14 @@ impl<R: Ring, const K: usize> Sub<TR<R, K>> for TR<R, K> {
     type Output = Self;
     fn sub(self, other: Self) -> Self {
         Self(zip_eq(self.0, other.0).map(|(s, o)| s - o).collect())
+    }
+}
+
+impl<R: Ring, const K: usize> Neg for TR<R, K> {
+    type Output = Self;
+
+    fn neg(self) -> Self::Output {
+        Self(self.0.iter().map(|&e_i| -e_i).collect())
     }
 }