pub fn back_propagate(&self, layer_outputs: &Vec<Vector>, expected: &Vector) -> Vector {
    let mut last_error = expected;
    for (i, weights) in self.weights.iter().enumerate() {
        last_error = weights.dot(&last_error); // the trait bound `ArrayBase<OwnedRepr<f64>, Dim<[usize; 2]>>: Dot<&ArrayBase<OwnedRepr<f64>, Dim<[usize; 1]>>>` is not satisfied

        // ...
    }
}

error[E0277]: the trait bound `ArrayBase<OwnedRepr<f64>, Dim<[usize; 2]>>: Dot<&ArrayBase<OwnedRepr<f64>, Dim<[usize; 1]>>>` is not satisfied
   --> src/brain.rs:23:40
    |
23  |             last_error = (weights).dot(&last_error);
    |                                    --- ^^^^^^^^^^^ the trait `Dot<&ArrayBase<OwnedRepr<f64>, Dim<[usize; 1]>>>` is not implemented for `ArrayBase<OwnedRepr<f64>, Dim<[usize; 2]>>`
    |                                    |
    |                                    required by a bound introduced by this call
    |
    = help: the following other types implement trait `Dot<Rhs>`:
              <ArrayBase<S, Dim<[usize; 1]>> as Dot<ArrayBase<S2, Dim<[usize; 1]>>>>
              <ArrayBase<S, Dim<[usize; 1]>> as Dot<ArrayBase<S2, Dim<[usize; 2]>>>>
              <ArrayBase<S, Dim<[usize; 2]>> as Dot<ArrayBase<S2, Dim<[usize; 1]>>>>
              <ArrayBase<S, Dim<[usize; 2]>> as Dot<ArrayBase<S2, Dim<[usize; 2]>>>>
note: required by a bound in `linalg::impl_linalg::<impl ArrayBase<S, Dim<[usize; 2]>>>::dot`
   --> /home/censored/.cargo/registry/src/index.crates.io-6f17d22bba15001f/ndarray-0.15.6/src/linalg/impl_linalg.rs:255:15
    |
253 |     pub fn dot<Rhs>(&self, rhs: &Rhs) -> <Self as Dot<Rhs>>::Output
    |            --- required by a bound in this associated function
254 |     where
255 |         Self: Dot<Rhs>,
    |               ^^^^^^^^ required by this bound in `linalg::impl_linalg::<impl ArrayBase<S, Dim<[usize; 2]>>>::dot`