And of dot_product

ipa-core/src/protocol/ipa_prf/malicious_security/lagrange.rs

@@ -162,14 +162,23 @@ where
 /// Computes the dot product of two arrays of the same size.
 /// It is isolated from Lagrange because there could be potential SIMD optimizations used
 fn dot_product<F: PrimeField, const N: usize>(a: &[F; N], b: &[F; N]) -> F {
+    // Staying in integers allows rustc to optimize this code properly, but puts a restriction
+    // on how large the prime field can be
+    debug_assert!(
+        2 * F::BITS + N.next_power_of_two().ilog2() <= 128,
+        "The prime field {} is too large for this dot product implementation",
+        F::PRIME.into()
+    );
+
+    let mut sum = 0;
+
     // I am cautious about using zip in hot code
     // https://github.com/rust-lang/rust/issues/103555
-
-    let mut acc = <F as MultiplyAccumulate>::Accumulator::new();
     for i in 0..N {
-        acc.multiply_accumulate(a[i], b[i]);
+        sum += a[i].as_u128() * b[i].as_u128();
     }
-    acc.take()
+
+    F::truncate_from(sum)
 }
 
 #[cfg(all(test, unit_test))]