Perry County is also a part of the larger Harrisburg-York-Lebanon, PA Combined Statistical Area (CSA), which combines the populations of Perry County as well as Adams, Cumberland, Dauphin, Lebanon and York Counties in Pennsylvania.
In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output. An example is the function that relates each real number x to its square x2.
Most calculus text books begin with a review of functions. A function is generally described as a mapping from one set of numbers, called the domain of the function, to another set, called the range. In simple form, if you put one number in to the function, you get another number out.