Hello everyone. I was taking a look at square-integrable functions.
$f\colon \mathbb{R}\to\mathbb{C}$ is square-integrable iff $\int_{-\infty}^{+\infty} \left|f(x)\right|^2\,\mathrm{d}x < \infty$.
Maybe because I was studying with the help of Wikipedia it is kind of unmotivated and I can't see it, but why is the square part important?