The standard deviation of a list of numbers is a measure of how much the numbers deviate from the average. If the standard deviation is small, the

numbers are clustered close to the average. If the standard deviation is

large, the numbers are scattered far from the average. The standard deviation,, of a list of numbers is defined as follows:

where is the average of the numbers , , … . Define a function

that takes a partially filled array of numbers as its arguments and returns the standard deviation of the numbers in the partially filled array. Since a

partially filled array requires two arguments, the function will actually have two formal parameters: an array parameter and a formal parameter of type int that gives the number of array positions used. The numbers in the array will be of type double. Embed your function in a suitable test program.

S

(xi–x )2

i = 1

NΣ

N

= ----------------------------