Piecewise Function
A function defined in terms of multiple formulas, think if-else statements in programming.
Example, let A = {0, 1..., 127}, a set of ordinal numbers in ASCII. Let f : A -> ASCII be defined b:
\begin{equation} f(n) = \left\{ \begin{array}{lr} \text{nonprintable control character} & \text{if } 0 \le n \le 31 \text{ or } n = 127\\ \text{uppercase letter} & \text{if } 65 \le n \le 90\\ \text{lowercase letter} & \text{if } 97 \le n \le 122\\ \text{other printable character} & \text{otherwise }\\ \end{array} \right\} \end{equation}
pg 121, 122