Task[edit]
Compute all three of the Pythagorean means of the set of integers 1 through 10 (inclusive).

Show that 



A
(

x

1


,
…
,

x

n


)
≥
G
(

x

1


,
…
,

x

n


)
≥
H
(

x

1


,
…
,

x

n


)


{\displaystyle A(x_{1},\ldots ,x_{n})\geq G(x_{1},\ldots ,x_{n})\geq H(x_{1},\ldots ,x_{n})}

 for this set of positive integers.

 The most common of the three means, the arithmetic mean, is the sum of the list divided by its length:
 



A
(

x

1


,
…
,

x

n


)
=




x

1


+
⋯
+

x

n



n




{\displaystyle A(x_{1},\ldots ,x_{n})={\frac {x_{1}+\cdots +x_{n}}{n}}}


 The geometric mean is the 



n


{\displaystyle n}

th root of the product of the list:
 



G
(

x

1


,
…
,

x

n


)
=




x

1


⋯

x

n




n





{\displaystyle G(x_{1},\ldots ,x_{n})={\sqrt[{n}]{x_{1}\cdots x_{n}}}}


 The harmonic mean is 



n


{\displaystyle n}

 divided by the sum of the reciprocal of each item in the list:
 



H
(

x

1


,
…
,

x

n


)
=


n



1

x

1




+
⋯
+


1

x

n









{\displaystyle H(x_{1},\ldots ,x_{n})={\frac {n}{{\frac {1}{x_{1}}}+\cdots +{\frac {1}{x_{n}}}}}}




See also
Tasks for calculating statistical measures



in one go
moving (sliding window)
moving (cumulative)

Mean
Arithmetic

Statistics/Basic
Averages/Arithmetic mean
Averages/Pythagorean means


Averages/Simple moving average




Geometric

Averages/Pythagorean means




Harmonic

Averages/Pythagorean means




Quadratic

Averages/Root mean square




Circular

Averages/Mean angle
Averages/Mean time of day




Median

Averages/Median




Mode

Averages/Mode




Standard deviation

Statistics/Basic



Cumulative standard deviation






import java.util.Arrays;
import java.util.List;
 
public class PythagoreanMeans {
    public static double arithmeticMean(List<Double> numbers) {
        if (numbers.isEmpty()) return Double.NaN;
        double mean = 0.0;
        for (Double number : numbers) {
            mean += number;
        }
        return mean / numbers.size();
    }
 
    public static double geometricMean(List<Double> numbers) {
        if (numbers.isEmpty()) return Double.NaN;
        double mean = 1.0;
        for (Double number : numbers) {
            mean *= number;
        }
        return Math.pow(mean, 1.0 / numbers.size());
    }
 
    public static double harmonicMean(List<Double> numbers) {
        if (numbers.isEmpty() || numbers.contains(0.0)) return Double.NaN;
        double mean = 0.0;
        for (Double number : numbers) {
            mean += (1.0 / number);
        }
        return numbers.size() / mean;
    }
 
    public static void main(String[] args) {
        Double[] array = {1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0};
        List<Double> list = Arrays.asList(array);
        double arithmetic = arithmeticMean(list);
        double geometric = geometricMean(list);
        double harmonic = harmonicMean(list);
        System.out.format("A = %f  G = %f  H = %f%n", arithmetic, geometric, harmonic);
        System.out.format("A >= G is %b, G >= H is %b%n", (arithmetic >= geometric), (geometric >= harmonic));
    }
}