Using a linear algebra library

What do you think of relying on an external linear algebra crate for the Vector representations and operations?
In this way, we could benefit from performance optimizations applied to the external crate.
Moreover, I think at a certain point we could face the need for Matrices (I am thinking, for example, to the implementation of the STFT) that for sure would be provided by the library.

Start by locating the current Vector representations and operations, then assess how a linear algebra crate could support them and possible future Matrices for STFT. The issue provides no file or test entry point; done would require a decided crate and a clear integration scope.

Written by the indexing model from the issue text.