Linear algebra for Rust implementation of K nearest Neighbors

KNN-linear-alg.rs

trait LinearAlg<T>
where
    T: Add + Sub,
{
    fn dot(&self, w: &[T]) -> T;

    fn subtract(&self, w: &[T]) -> Vec<T>;

    fn sum_of_squares(&self) -> T;

    fn distance(&self, w: &[T]) -> f64;
}

impl LinearAlg<f64> for Vec<f64> {
    fn dot(&self, w: &[f64]) -> f64 {
        assert_eq!(self.len(), w.len());
        self.iter().zip(w).map(|(v_i, w_i)| v_i * w_i).sum()
    }

    fn subtract(&self, w: &[f64]) -> Vec<f64> {
        assert_eq!(self.len(), w.len());
        self.iter().zip(w).map(|(v_i, w_i)| v_i - w_i).collect()
    }

    fn sum_of_squares(&self) -> f64 {
        self.dot(&self)
    }

    fn distance(&self, w: &[f64]) -> f64 {
        assert_eq!(self.len(), w.len());
        self.subtract(w).sum_of_squares().sqrt()
    }
}