> "Do vectors have to be lists of numbers?" No. They just have to satisfy the vectors axioms (greatly simplifying, you can add vectors together and multiply t

> "Do vectors have to be lists of numbers?" No. They just have to satisfy the vectors axioms (greatly simplifying, you can add vectors together and multiply them by scalars , and they behave as you would expect - associative, commutative, distributive, etc as appropriate.) So, in this regard, functions can be vectors, if you define addition to be pointwise addition. For example, consider the set of continuous functions on the unit interval [0, 1]. Add two together and you get another continuous function on the unit interval, multiply by a scalar and you get another continuous function on the unit interval, etc.