Square Integrable

A function $f(x)$ is said to be square integrable if

$$\int_{-\infty}^\infty \vert f(x)\vert^2\,dx$$

is finite.

See also Integrable, L2-Norm, Titchmarsh Theorem

References

Sansone, G. ``Square Integrable Functions.'' §1.1 in Orthogonal Functions, rev. English ed. New York: Dover, pp. 1-2, 1991.