Hard Clipper

$$f(x) = \left\{\begin{array}{ll} -1, & x\leq -1 \\ [5pt] x, & -1 \leq x \leq 1 \\ [5pt] 1, & x\geq 1 \\ \end{array}\right.$$

where $x$ denotes the current input sample $x(n)$, and $f(x)$ denotes the output of the nonlinearity.