Editing Domain of a function (section)

=== Examples ===

* The function <math>f</math> defined by <math>f(x)=\frac{1}{x}</math> cannot be evaluated at 0. Therefore, the natural domain of <math>f</math> is the set of real numbers excluding 0, which can be denoted by <math>\mathbb{R} \setminus \{ 0 \}</math> or <math>\{x\in\mathbb R:x\ne 0\}</math>.
* The [[piecewise]] function <math>f</math> defined by <math>f(x) = \begin{cases}
1/x&x\not=0\\
0&x=0
\end{cases},</math> has as its natural domain the set <math>\mathbb{R}</math> of real numbers.
* The [[square root]] function <math>f(x)=\sqrt x</math> has as its natural domain the set of non-negative real numbers, which can be denoted by <math>\mathbb R_{\geq 0}</math>, the interval <math>[0,\infty)</math>, or <math>\{x\in\mathbb R:x\geq 0\}</math>.
* The [[tangent function]], denoted <math>\tan</math>, has as its natural domain the set of all real numbers which are not of the form <math>\tfrac{\pi}{2} + k \pi</math> for some [[integer]] <math>k</math>, which can be written as <math>\mathbb R \setminus \{\tfrac{\pi}{2}+k\pi: k\in\mathbb Z\}</math>.