dirichlet function
The Dirichlet function is defined on \(\mathbb{R}\) by the following rule:
\[
D(x) =
\begin{cases}
1 & \text{if } x \in \mathbb{Q} \\[6pt]
0 & \text{if } x \in \mathbb{R} \setminus \mathbb{Q}
\end{cases}
\]
The Dirichlet function is defined on \(\mathbb{R}\) by the following rule:
\[
D(x) =
\begin{cases}
1 & \text{if } x \in \mathbb{Q} \\[6pt]
0 & \text{if } x \in \mathbb{R} \setminus \mathbb{Q}
\end{cases}
\]