Example 2: Numerical Rules

Click here to open an associated Mathcad worksheet:

A table of values is another way of representing a rule relating two variable quantities. Here the two variable quantities are again "the weather"  w  (given this time by temperature) and "what I wear"  d  (shoe color again). The rule  g  says to read the table:  d = g(w)  is the unique shoe color associated with a particular temperature  w .

The rule is undefined for many temperatures, like 25 degrees. We say that 25 is not in the domain of the rule. The domain of a function is just the collection of inputs for which the rule will provide an output.

However, the rule is not ambiguous. This is a function.