| function, zero for all negative values of the independent variable and equal to one for all positive values|
Note 1 to entry: See Figure 1 below for a graphical representation of ε(t). The value ε(0) may remain undefined or may be defined according to the context.
Note 2 to entry: ε(x − x0) denotes a unit step at the value x0 of the independent variable x.
Note 3 to entry: Notation H(x) is also used. Notation ϑ(t) is used for the unit step function of time. Notation ϒ(x) has also been used.
Figure 1 – Représentation graphique de ε(t)
Figure 1 – Graphical representation of ε(t)