Function Difference
$\Delta f$ is a finite difference between the values of $f$ function at two given points. For a single variable function:
(1)\begin{align} \Delta f(x) = f(x+\Delta x)-f(x) \end{align}
where $\Delta x$ is a change in the independent variable $x$.
Note: $\Delta f^2$ is the same as $(\Delta f)^2$. The difference in $f^2$ is denoted by $\Delta \left(f^2 \right)$.
page revision: 3, last edited: 12 Aug 2011 19:28