. "The wave equation is an important second-order linear partial differential equation for the description of waves \u2013 as they occur in physics \u2013 such as sound waves, light waves and water waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics.Historically, the problem of a vibrating string such as that of a musical instrument was studied by Jean le Rond d'Alembert, Leonhard Euler, Daniel Bernoulli, and Joseph-Louis Lagrange."@en . . . .