- Assume we have a function:
$$\begin{equation}R_a(x)=\begin{cases}0&\mbox{ x<-a or x>a}\\ {1\over 2a}&\mbox{-a<x<a}\end{cases}\end{equation}$$
$$\begin{equation}R_a(x)=\begin{cases}0&\mbox{ x<-a or x>a}\\ {1\over 2a}&\mbox{-a<x<a}\end{cases}\end{equation}$$