Function subset_convolution

pub fn subset_convolution<T>(f: Vec<T>, g: Vec<T>) -> Vec<T>
where
    T: Copy + Default + Add<Output = T> + Sub<Output = T> + Mul<Output = T>,

$h_k = \sum_{i \lor j = k, i \land j = 0} f_i g_j$を満たす$h$を求める。

Requirements

f.len() = g.len()は2の累乗