Sturm-Liouville form

Etymology
Named after (1803–1855) and  (1809–1882).

Noun
$$\frac{d}{dx}\!\!\left[\,p(x)\frac{dy}{dx}\right] + q(x)y = -\lambda\, w(x)y, $$ for given coefficient functions $p(x)$, $q(x)$, and $w(x)$, an unknown function y = y(x) of the free variable $x$, and an unknown constant λ.
 * 1)  the form of a real differential equation expressed as: