Partial Differential Equations
www.math.toronto.edu › ivrii › PDE-textbookA partial di erential equation is an equation for a function which depends on more than one independent variable which involves the independent variables, the function, and partial derivatives of the function: F(x;y;u(x;y);u x(x;y);u y(x;y);u xx(x;y);u xy(x;y);u yx(x;y);u yy(x;y)) = 0: This is an example of a PDE of order 2. Solving an equation like this
Wave equation - Wikipedia
https://en.wikipedia.org/wiki/Wave_equationThe wave equation is a second-order linear partial differential equation for the description of waves—as they occur in classical physics—such as mechanical waves (e.g. water waves, sound waves and seismic waves) or light waves. It arises in fields like acoustics, electromagnetics, and fluid dynamics. Due to the fact that the second order wave equation describes the superposition of an incoming wave and an outgoing wave (i.e. rather a standing wave field) it is also called "Two-wa…
PARTIAL DIFFERENTIAL EQUATIONS - UC Santa Barbara
web.math.ucsb.edu › ~grigoryan › 124AIn contrast to ODEs, a partial di erential equation (PDE) contains partial derivatives of the depen-dent variable, which is an unknown function in more than one variable x;y;:::. Denoting the partial derivative of @u @x = u x, and @u @y = u y, we can write the general rst order PDE for u(x;y) as F(x;y;u(x;y);u x(x;y);u y(x;y)) = F(x;y;u;u x;u y) = 0: (1.1)