Definition:Exterior Derivative

Definition
Let an exact $n$-form $\omega$ be given on an $m$-manifold, with local coordinates are $x_1, x_2, \dots, x_m$.

Let a local coordinate expression for $\omega$ be given:


 * $\omega = f (x_1, \dots, x_m) \mathrm d x_{\phi(1)} \wedge \mathrm d x_{\phi(2)} \wedge \dots \wedge \mathrm d x_{\phi(n)}$

where $\phi:\left\{{1, \dots, n }\right\} \to \left\{{1, \dots, m}\right\}$ is an injection which determines which coordinate vectors $\omega$ acts on.

The exterior derivative $\mathrm d \omega$ is the $(n+1)$-form defined as:


 * $\displaystyle \mathrm d \omega = \left({\sum_{k \mathop = 1}^m \frac{\partial f}{\partial x_k} \mathrm d x_k}\right) \wedge \mathrm d x_{\phi(1)} \wedge \mathrm d x_{\phi(2)} \wedge \dots \wedge \mathrm d x_{\phi(n)}$

For inexact forms:
 * $\mathrm d (a+b) = \mathrm d a + \mathrm d b$

Also see

 * Manipulation of Exterior Derivative


 * Definition:Wedge Product