# Definition:Differential/Notation

## Notation for Differential

There are various notations for the differential of a function $f$ at $x$:

• $\d f \left({x}\right)$
• $\d f_x$
• $\d_x f$
• $D f \left({x}\right)$
• $D_x f$

Substituting $\d y$ for $\d f \left({x; h}\right)$ and $\d x$ for $h$, the following notation emerges:

$\d y = f' \left({x}\right) \rd x$

hence:

$\d y = \dfrac {\d y} {\d x} \rd x$