Matrix is, roughly speaking,
a 2-dimensional rectangular array of numbers.
Then, I was wondering if there could exist a generalization of a matrix that consists of an n-dimensional higher-spacish rectangular array of numbers. For $d=3$, we can think of a cube $n\times n\times n$, whose every unit cube contains a number. Does linear algebra go as far as that? Or, will it stop at our 2-dimensional matrices? Why? Why not?