Consider unrolling take_even_odd to remove the if statement

[kevaundray]

This has been taken from Benedikt Wagner's document.

Link:

rust-eth-kzg/cryptography/polynomial/src/domain.rs

Line 274 in e043452

for (index, value) in list.iter().enumerate() {

It may improve performance, if a single loop iteration takes two indices.

Some rough pseudocode for this could be:

fn take_even_odd<T: Clone>(list: &[T]) -> (Vec<T>, Vec<T>) {
    assert!(list.len() % 2 == 0, "List length must be even");

    let mut even = Vec::with_capacity(list.len() / 2);
    let mut odd = Vec::with_capacity(list.len() / 2);
    
    for chunk in list.chunks_exact(2) {
        even.push(chunk[0].clone());
        odd.push(chunk[1].clone());
    }
    
    (even, odd)
}

Related to #246

[b-wagn]

This may be worth a try. Not sure if it really improves performance :)

[kevaundray]

We now use the iterative version of FFT which does not require take_even_odd! This was added in #274