Chapter 19, Problem 9E

Explanation of Solution

“stdev” method:

//definition of "stdev" method

public static double stdev (double[] a)

{

    // declare the variable

double avg = DoubleStream.of (a).average().getAsDouble();

/*return the standard deviation of the doubles in an array*/

    return DoubleStream.of (a)

        //call the "map" method

.map(n -> Math.pow (n – avg, 2))

        //call the "average" method

        ...