The '''divergence''' is a way of expressing a certain type of derivative of a [[vector field]]. It is typically a field of 3-dimensional vectors defined on 3-dimensional space, but other dimensions are possible. The divergence of a vector field is a [[scalar field]], that is, just a number at each point in space.
The divergence is written as though it were the [[dot product]] of the special symbol "<math>\nabla</math>" (which is commonly called "del" or "nabla") , with the given vector field, like this: <math>\nabla \cdot \vec V</math>. This is usually pronounced "div V" or "del dot V".
In ordinary [[Cartesian coordinates]], the divergence is calculated as: