Definition:Reciprocal

Definition
Let $x \in \R$ be a real number such that $x \ne 0$.

Then $\dfrac 1 x$ is called the reciprocal of $x$.

The real function $f: \R_{\ne 0} \to \R$ defined as:


 * $\forall x \in \R_{\ne 0}: \map f x = \dfrac 1 x$

is called the reciprocal function.

Warning
Note the domain of the function $f: \R \setminus \set 0 \to \R$.

That is, $\dfrac 1 0$ is not defined.

Also see

 * Definition:Harmonic Numbers
 * Definition:Natural Logarithm