Editing Equation (section)

===Ordinary differential equations===
{{main|Ordinary differential equation}}
An [[ordinary differential equation]] or ODE is an equation containing a function of one [[independent variable]] and its derivatives. The term "''ordinary''" is used in contrast with the term [[partial differential equation]], which may be with respect to ''more than'' one independent variable.

Linear differential equations, which have solutions that can be added and multiplied by coefficients, are well-defined and understood, and exact closed-form solutions are obtained. By contrast, ODEs that lack additive solutions are nonlinear, and solving them is far more intricate, as one can rarely represent them by [[elementary functions]] in closed form: Instead, exact and analytic solutions of ODEs are in series or integral form. Graphical and [[numerical ordinary differential equations|numerical]] methods, applied by hand or by computer, may approximate solutions of ODEs and perhaps yield useful information, often sufficing in the absence of exact, analytic solutions.