0. Set of symbols
1. Alphabet
2. Deduction system
3. Theory
4. Zermelo-Fraenkel set theory
5. Set
6. Binary cartesian set product
7. Binary relation
8. Map
9. Function
10. Real function
11. Euclidean real function
12. Basic real function
13. Basic rational function
14. Basic integer function
15. Basic natural number function
16. Basic boolean function
17. Indicator function
Heaviside function
Formulation 0
The Heaviside function is the D218: Basic boolean function \begin{equation} \mathbb{R} \to \{ 0, 1 \}, \quad x \mapsto \begin{cases} 1, \quad & x \geq 0 \\ 0, \quad & x < 0 \end{cases} \end{equation}
Formulation 1
The Heaviside function is the D218: Basic boolean function \begin{equation} \mathbb{R} \to \{ 0, 1 \}, \quad x \mapsto I_{[0, \infty)}(x) \end{equation}
Also known as
Heaviside step function