The wave equation is a mathematical description governing the PROPAGATION of waves. For the string, for example, the wave equation takes the form

in terms of the transverse displacement of the string, .

For one-dimensional waves in air it takes the form

in terms of the ACOUSTIC PRESSURE *p*(*x*,*t*).

These equations are partial differential equations (PDEs), because
they involve partial derivatives in terms of both the variables
*x* and *t*. They are second order PDEs.

Tue Feb 25 21:24:33 EST 1997