From 9d51abd843da44a3391721a158638ecf970865d1 Mon Sep 17 00:00:00 2001
From: danielmasny <daniel.masny@rub.de>
Date: Tue, 20 Feb 2024 12:02:55 -0800
Subject: [PATCH] address comments

---
 .../ipa_prf/malicious_security/lagrange.rs    | 46 +++++++++----------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/ipa-core/src/protocol/ipa_prf/malicious_security/lagrange.rs b/ipa-core/src/protocol/ipa_prf/malicious_security/lagrange.rs
index 10d79dd25..17254ba96 100644
--- a/ipa-core/src/protocol/ipa_prf/malicious_security/lagrange.rs
+++ b/ipa-core/src/protocol/ipa_prf/malicious_security/lagrange.rs
@@ -44,7 +44,7 @@ where
             }
             *d = d.invert();
         }
-        CanonicalLagrangeDenominator { denominator }
+        Self { denominator }
     }
 }
 
@@ -63,9 +63,9 @@ where
 {
     /// generates a `CanonicalLagrangeTable` from `CanoncialLagrangeDenominators` for a single output point
     /// The "x coordinate" of the output point is `x_output`.
-    pub fn new(denominator: &CanonicalLagrangeDenominator<F, N>, x_output: &F) -> Self {
-        let mut table = denominator.denominator.clone();
-        compute_table_row(x_output, &mut table);
+    pub fn new(denominator: CanonicalLagrangeDenominator<F, N>, x_output: &F) -> Self {
+        let mut table = denominator.denominator;
+        Self::compute_table_row(x_output, &mut table);
         LagrangeTable::<F, N, U1> {
             table: GenericArray::from_array([table; 1]),
         }
@@ -102,6 +102,22 @@ where
                 .fold(F::ZERO, |acc, (&base, &y)| acc + base * y);
         }
     }
+
+    /// helper function to compute a single row of `CanonicalLagrangeTable`
+    ///
+    /// ## Panics
+    /// When the field size is too small for `N` evaluation points
+    fn compute_table_row(x_output: &F, table_row: &mut GenericArray<F, N>)
+    where
+        F: Field,
+        N: ArrayLength,
+    {
+        for (i, entry) in table_row.iter_mut().enumerate() {
+            for j in (0usize..N::USIZE).filter(|&j| j != i) {
+                *entry *= *x_output - F::try_from(j as u128).unwrap();
+            }
+        }
+    }
 }
 
 impl<F, N, M> From<CanonicalLagrangeDenominator<F, N>> for LagrangeTable<F, N, M>
@@ -113,34 +129,18 @@ where
     fn from(value: CanonicalLagrangeDenominator<F, N>) -> Self {
         // assertion that field is large enough
         // also checks that `try_from` for conversions from sufficiently small `u128` to `F` do not panic
-        debug_assert!(F::BITS > usize::BITS - N::USIZE.leading_zeros() - M::USIZE.leading_zeros());
+        debug_assert!(F::BITS > usize::BITS - (N::USIZE + M::USIZE).leading_zeros());
 
         let mut table = iter::repeat(value.denominator.clone())
             .take(M::USIZE)
             .collect::<GenericArray<_, _>>();
         table.iter_mut().enumerate().for_each(|(i, row)| {
-            compute_table_row(&F::try_from((i + N::USIZE) as u128).unwrap(), row);
+            Self::compute_table_row(&F::try_from((i + N::USIZE) as u128).unwrap(), row);
         });
         LagrangeTable { table }
     }
 }
 
-/// helper function to compute a single row of `CanonicalLagrangeTable`
-///
-/// ## Panics
-/// When the field size is too small for `N` evaluation points
-fn compute_table_row<F, N>(x_output: &F, table_row: &mut GenericArray<F, N>)
-where
-    F: Field,
-    N: ArrayLength,
-{
-    for (i, entry) in table_row.iter_mut().enumerate() {
-        for j in (0usize..N::USIZE).filter(|&j| j != i) {
-            *entry *= *x_output - F::try_from(j as u128).unwrap();
-        }
-    }
-}
-
 #[cfg(all(test, unit_test))]
 mod test {
     use std::iter;
@@ -216,7 +216,7 @@ mod test {
             let polynomial = Polynomial::from(polynomial_monomial_form.clone());
             let denominator = CanonicalLagrangeDenominator::<TestField,U32>::new();
             // generate table using new
-            let lagrange_table = LagrangeTable::<TestField,U32,U1>::new(&denominator,&output_point);
+            let lagrange_table = LagrangeTable::<TestField,U32,U1>::new(denominator,&output_point);
             let output = lagrange_table.eval(&polynomial);
             assert_eq!(output,output_expected);
         }