From 02f0715040fb99e8b0650cad58a172e8e1c906af Mon Sep 17 00:00:00 2001
From: wborgeaud <williamborgeaud@gmail.com>
Date: Wed, 14 Jul 2021 08:39:09 +0200
Subject: [PATCH] PR feedback

---
 src/plonk_common.rs | 24 +++++++++++++++---------
 src/verifier.rs     |  5 +++++
 2 files changed, 20 insertions(+), 9 deletions(-)

diff --git a/src/plonk_common.rs b/src/plonk_common.rs
index 5179b474..b1f29803 100644
--- a/src/plonk_common.rs
+++ b/src/plonk_common.rs
@@ -73,7 +73,7 @@ pub(crate) fn eval_vanishing_poly<F: Extendable<D>, const D: usize>(
     gammas: &[F],
     alphas: &[F],
 ) -> Vec<F::Extension> {
-    let max_degree = common_data.quotient_degree_factor;
+    let partial_products_degree = common_data.quotient_degree_factor;
     let (num_prods, final_num_prod) = common_data.num_partial_products;
 
     let constraint_terms =
@@ -113,12 +113,15 @@ pub(crate) fn eval_vanishing_poly<F: Extendable<D>, const D: usize>(
         // The partial products considered for this iteration of `i`.
         let current_partial_products = &partial_products[i * num_prods..(i + 1) * num_prods];
         // Check the quotient partial products.
-        let mut partial_product_check =
-            check_partial_products(&quotient_values, current_partial_products, max_degree);
+        let mut partial_product_check = check_partial_products(
+            &quotient_values,
+            current_partial_products,
+            partial_products_degree,
+        );
         // The first checks are of the form `q - n/d` which is a rational function not a polynomial.
         // We multiply them by `d` to get checks of the form `q*d - n` which low-degree polynomials.
         denominator_values
-            .chunks(max_degree)
+            .chunks(partial_products_degree)
             .zip(partial_product_check.iter_mut())
             .for_each(|(d, q)| {
                 *q *= d.iter().copied().product();
@@ -160,7 +163,7 @@ pub(crate) fn eval_vanishing_poly_base<F: Extendable<D>, const D: usize>(
     alphas: &[F],
     z_h_on_coset: &ZeroPolyOnCoset<F>,
 ) -> Vec<F> {
-    let max_degree = common_data.quotient_degree_factor;
+    let partial_products_degree = common_data.quotient_degree_factor;
     let (num_prods, final_num_prod) = common_data.num_partial_products;
 
     let constraint_terms =
@@ -199,13 +202,16 @@ pub(crate) fn eval_vanishing_poly_base<F: Extendable<D>, const D: usize>(
 
         // The partial products considered for this iteration of `i`.
         let current_partial_products = &partial_products[i * num_prods..(i + 1) * num_prods];
-        // Check the numerator partial products.
-        let mut partial_product_check =
-            check_partial_products(&quotient_values, current_partial_products, max_degree);
+        // Check the quotient partial products.
+        let mut partial_product_check = check_partial_products(
+            &quotient_values,
+            current_partial_products,
+            partial_products_degree,
+        );
         // The first checks are of the form `q - n/d` which is a rational function not a polynomial.
         // We multiply them by `d` to get checks of the form `q*d - n` which low-degree polynomials.
         denominator_values
-            .chunks(max_degree)
+            .chunks(partial_products_degree)
             .zip(partial_product_check.iter_mut())
             .for_each(|(d, q)| {
                 *q *= d.iter().copied().product();
diff --git a/src/verifier.rs b/src/verifier.rs
index 64d4b371..d7c96365 100644
--- a/src/verifier.rs
+++ b/src/verifier.rs
@@ -60,6 +60,11 @@ pub(crate) fn verify<F: Extendable<D>, const D: usize>(
     let quotient_polys_zeta = &proof.openings.quotient_polys;
     let zeta_pow_deg = zeta.exp_power_of_2(common_data.degree_bits);
     let z_h_zeta = zeta_pow_deg - F::Extension::ONE;
+    // `quotient_polys_zeta` holds `num_challenges * quotient_degree_factor` evaluations.
+    // Each chunk of `quotient_degree_factor` holds the evaluations of `t_0(zeta),...,t_{quotient_degree_factor-1}(zeta)`
+    // where the "real" quotient polynomial is `t(X) = t_0(X) + t_1(X)*X^n + t_2(X)*X^{2n} + ...`.
+    // So to reconstruct `t(zeta)` we can compute `reduce_with_powers(chunk, zeta^n)` for each
+    // `quotient_degree_factor`-sized chunk of the original evaluations.
     for (i, chunk) in quotient_polys_zeta
         .chunks(common_data.quotient_degree_factor)
         .enumerate()