Averages/Pythagorean means
From Rosetta Code
You are encouraged to solve this task according to the task description, using any language you may know.
Compute all three of the Pythagorean means of the set of integers 1 through 10.
Show that 
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:
- The geometric mean is the nth root of the product of the list:
![G(x_1, \ldots, x_n) = \sqrt[n]{x_1 \cdots x_n}](/mw/images/math/1/2/5/12595bb2b15b5d8b7263aba68c137db3.png)
- The harmonic mean is n divided by the sum of the reciprocal of each item in the list:
C.f. Averages/Root mean square
[edit] ActionScript
function arithmeticMean(v:Vector.<Number>):Number
{
var sum:Number = 0;
for(var i: uint = 0; i < v.length; i++)
sum += v[i];
return sum/v.length;
}
function geometricMean(v:Vector.<Number>):Number
{
var product:Number = 1;
for(var i: uint = 0; i < v.length; i++)
product *= v[i];
return Math.pow(product, 1/v.length);
}
function harmonicMean(v:Vector.<Number>):Number
{
var sum:Number = 0;
for(var i: uint = 0; i < v.length; i++)
sum += 1/v[i];
return v.length/sum;
}
var list:Vector.<Number> = Vector.<Number>([1,2,3,4,5,6,7,8,9,10]);
trace("Arithmetic: ", arithmeticMean(list));
trace("Geometric: ", geometricMean(list));
trace("Harmonic: ", harmonicMean(list));
[edit] Ada
pythagorean_means.ads:
package Pythagorean_Means is
type Set is array (Positive range <>) of Float;
function Arithmetic_Mean (Data : Set) return Float;
function Geometric_Mean (Data : Set) return Float;
function Harmonic_Mean (Data : Set) return Float;
end Pythagorean_Means;
pythagorean_means.adb:
with Ada.Numerics.Generic_Elementary_Functions;
package body Pythagorean_Means is
package Math is new Ada.Numerics.Generic_Elementary_Functions (Float);
function "**" (Left, Right : Float) return Float renames Math."**";
function Arithmetic_Mean (Data : Set) return Float is
Sum : Float := 0.0;
begin
for I in Data'Range loop
Sum := Sum + Data (I);
end loop;
return Sum / Float (Data'Length);
end Arithmetic_Mean;
function Geometric_Mean (Data : Set) return Float is
Product : Float := 1.0;
begin
for I in Data'Range loop
Product := Product * Data (I);
end loop;
return Product**(1.0/Float(Data'Length));
end Geometric_Mean;
function Harmonic_Mean (Data : Set) return Float is
Reciprocal_Sum : Float := 0.0;
begin
for I in Data'Range loop
Reciprocal_Sum := Reciprocal_Sum + Data (I)**(-1);
end loop;
return Float (Data'Length) / Reciprocal_Sum;
end Harmonic_Mean;
end Pythagorean_Means;
example main.adb:
with Ada.Text_IO;
with Pythagorean_Means;
procedure Main is
My_Set : Pythagorean_Means.Set := (1.0, 2.0, 3.0, 4.0, 5.0,
6.0, 7.0, 8.0, 9.0, 10.0);
Arithmetic_Mean : Float := Pythagorean_Means.Arithmetic_Mean (My_Set);
Geometric_Mean : Float := Pythagorean_Means.Geometric_Mean (My_Set);
Harmonic_Mean : Float := Pythagorean_Means.Harmonic_Mean (My_Set);
begin
Ada.Text_IO.Put_Line (Float'Image (Arithmetic_Mean) & " >= " &
Float'Image (Geometric_Mean) & " >= " &
Float'Image (Harmonic_Mean));
end Main;
[edit] ALGOL 68
main: (
INT count:=0;
LONG REAL f, sum:=0, prod:=1, resum:=0;
FORMAT real = $g(0,4)$; # preferred real format #
FILE fbuf; STRING sbuf; associate(fbuf,sbuf);
BOOL opts := TRUE;
FOR i TO argc DO
IF opts THEN # skip args up to the - token #
opts := argv(i) NE "-"
ELSE
rewind(fbuf); sbuf := argv(i); get(fbuf,f);
count +:= 1;
sum +:= f;
prod *:= f;
resum +:= 1/f
FI
OD;
printf(($"c: "f(real)l"s: "f(real)l"p: "f(real)l"r: "f(real)l$,count,sum,prod,resum));
printf(($"Arithmetic mean = "f(real)l$,sum/count));
printf(($"Geometric mean = "f(real)l$,prod**(1/count)));
printf(($"Harmonic mean = "f(real)l$,count/resum))
)
Lunix command:
a68g Averages_Pythagorean_means.a68 - 1 2 3 4 5 6 7 8 9 10
Output:
c: 10.0000 s: 55.0000 p: 3628800.0000 r: 2.9290 Arithmetic mean = 5.5000 Geometric mean = 4.5287 Harmonic mean = 3.4142
[edit] APL
arithmetic←{(+/⍵)÷⍴⍵}
geometric←{(×/⍵)*÷⍴⍵}
harmonic←{(⍴⍵)÷(+/÷⍵)}
x←⍳10
arithmetic x
5.5
geometric x
4.528728688
harmonic x
3.414171521
[edit] AutoHotkey
A := ArithmeticMean(1, 10)
G := GeometricMean(1, 10)
H := HarmonicMean(1, 10)
If G Between %H% And %A%
Result := "True"
Else
Result := "False"
MsgBox, %A%`n%G%`n%H%`n%Result%
;---------------------------------------------------------------------------
ArithmeticMean(a, b) { ; of integers a through b
;---------------------------------------------------------------------------
n := b - a + 1
Loop, %n%
Sum += (a + A_Index - 1)
Return, Sum / n
}
;---------------------------------------------------------------------------
GeometricMean(a, b) { ; of integers a through b
;---------------------------------------------------------------------------
n := b - a + 1
Prod := 1
Loop, %n%
Prod *= (a + A_Index - 1)
Return, Prod ** (1 / n)
}
;---------------------------------------------------------------------------
HarmonicMean(a, b) { ; of integers a through b
;---------------------------------------------------------------------------
n := b - a + 1
Loop, %n%
Sum += 1 / (a + A_Index - 1)
Return, n / Sum
}
Message box shows:
5.500000 4.528729 3.414172 True
[edit] AWK
#!/usr/bin/awk -f
{
x = $1; # value of 1st column
A += x;
G += log(x);
H += 1/x;
N++;
}
END {
print "Arithmethic mean: ",A/N;
print "Geometric mean : ",exp(G/N);
print "Harmonic mean : ",N/H;
}
[edit] BBC BASIC
The arithmetic and harmonic means use BBC BASIC's built-in array operations; only the geometric mean needs a loop.
DIM a(9)
a() = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
PRINT "Arithmetic mean = " ; FNarithmeticmean(a())
PRINT "Geometric mean = " ; FNgeometricmean(a())
PRINT "Harmonic mean = " ; FNharmonicmean(a())
END
DEF FNarithmeticmean(a())
= SUM(a()) / (DIM(a(),1)+1)
DEF FNgeometricmean(a())
LOCAL a, I%
a = 1
FOR I% = 0 TO DIM(a(),1)
a *= a(I%)
NEXT
= a ^ (1/(DIM(a(),1)+1))
DEF FNharmonicmean(a())
LOCAL b()
DIM b(DIM(a(),1))
b() = 1/a()
= (DIM(a(),1)+1) / SUM(b())
Output:
Arithmetic mean = 5.5 Geometric mean = 4.52872869 Harmonic mean = 3.41417152
[edit] C
#include <stdio.h>
#include <stdlib.h> // atoi()
#include <math.h> // pow()
int main(int argc, char* argv[])
{
int i, count=0;
double f, sum=0.0, prod=1.0, resum=0.0;
for (i=1; i<argc; ++i) {
f = atof(argv[i]);
count++;
sum += f;
prod *= f;
resum += (1.0/f);
}
//printf(" c:%d\n s:%f\n p:%f\n r:%f\n",count,sum,prod,resum);
printf("Arithmetic mean = %f\n",sum/count);
printf("Geometric mean = %f\n",pow(prod,(1.0/count)));
printf("Harmonic mean = %f\n",count/resum);
return 0;
}
[edit] C++
#include <vector>
#include <iostream>
#include <numeric>
#include <cmath>
#include <algorithm>
double toInverse ( int i ) {
return 1.0 / i ;
}
int main( ) {
std::vector<int> numbers ;
for ( int i = 1 ; i < 11 ; i++ )
numbers.push_back( i ) ;
double arithmetic_mean = std::accumulate( numbers.begin( ) , numbers.end( ) , 0 ) / 10.0 ;
double geometric_mean =
pow( std::accumulate( numbers.begin( ) , numbers.end( ) , 1 , std::multiplies<int>( ) ), 0.1 ) ;
std::vector<double> inverses ;
inverses.resize( numbers.size( ) ) ;
std::transform( numbers.begin( ) , numbers.end( ) , inverses.begin( ) , toInverse ) ;
double harmonic_mean = 10 / std::accumulate( inverses.begin( ) , inverses.end( ) , 0.0 ); //initial value of accumulate must be a double!
std::cout << "The arithmetic mean is " << arithmetic_mean << " , the geometric mean "
<< geometric_mean << " and the harmonic mean " << harmonic_mean << " !\n" ;
return 0 ;
}
Output:
The arithmetic mean is 5.5 , the geometric mean 4.52873 and the harmonic mean 3.41417 !
[edit] C#
The standard Linq extension method Average provides arithmetic mean. This example adds two more extension methods for the geometric and harmonic means.
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
namespace PythMean
{
static class Program
{
static void Main(string[] args) {
var nums = from n in Enumerable.Range(1, 10) select (double)n;
var a = nums.Average();
var g = nums.Gmean();
var h = nums.Hmean();
Console.WriteLine("Arithmetic mean {0}", a);
Console.WriteLine("Geometric mean {0}", g);
Console.WriteLine("Harmonic mean {0}", h);
Debug.Assert(a >= g && g >= h);
}
// Geometric mean extension method.
static double Gmean(this IEnumerable<double> n) {
return Math.Pow(n.Aggregate((s, i) => s * i), 1.0 / n.Count());
}
// Harmonic mean extension method.
static double Hmean(this IEnumerable<double> n) {
return n.Count() / n.Sum(i => 1 / i);
}
}
}
Output:
Arithmetic mean 5.5 Geometric mean 4.52872868811677 Harmonic mean 3.41417152147406
[edit] Common Lisp
(defun generic-mean (nums reduce-op final-op)
(funcall final-op (reduce reduce-op nums)))
(defun a-mean (nums)
(generic-mean nums #'+ (lambda (x) (/ x (length nums)))))
(defun g-mean (nums)
(generic-mean nums #'* (lambda (x) (expt x (/ 1 (length nums))))))
(defun h-mean (nums)
(generic-mean nums
(lambda (x y) (+ x
(/ 1 y)))
(lambda (x) (/ (length nums) x))))
(let ((numbers (loop for i from 1 to 10 collect i)))
(let ((a-mean (a-mean numbers))
(g-mean (g-mean numbers))
(h-mean (h-mean numbers)))
(assert (> a-mean g-mean h-mean))
(format t "a-mean ~a~%" a-mean)
(format t "g-mean ~a~%" g-mean)
(format t "h-mean ~a~%" h-mean)))
[edit] Clojure
(use '[clojure.contrib.math :only (expt)])
(defn a-mean [coll]
(/ (apply + coll) (count coll)))
(defn g-mean [coll]
(expt (apply * coll) (/ (count coll))))
(defn h-mean [coll]
(/ (count coll) (apply + (map / coll))))
(let [numbers (range 1 11)
a (a-mean numbers) g (g-mean numbers) h (h-mean numbers)]
(println a ">=" g ">=" h)
(>= a g h))
[edit] D
import std.stdio, std.algorithm, std.range, std.functional;
auto amean(T)(T data) {
return data.reduce!q{a + b}() / data.length;
}
auto gmean(T)(T data) {
return data.reduce!q{a * b}() ^^ (1.0 / data.length);
}
auto hmean(T)(T data) {
return data.length / data.reduce!q{1.0/a + b}();
}
void main() {
auto m = adjoin!(hmean, gmean, amean)(iota(1.0L, 11.0L));
writefln("%.19f %.19f %.19f", m.tupleof);
assert([m.tupleof].isSorted());
}
- Output:
0.9891573712076470036 4.5287286881167647619 5.5000000000000000000
[edit] Delphi
program AveragesPythagoreanMeans;
{$APPTYPE CONSOLE}
uses Types, Math;
function ArithmeticMean(aArray: TDoubleDynArray): Double;
var
lValue: Double;
begin
Result := 0;
for lValue in aArray do
Result := Result + lValue;
if Result > 0 then
Result := Result / Length(aArray);
end;
function GeometricMean(aArray: TDoubleDynArray): Double;
var
lValue: Double;
begin
Result := 1;
for lValue in aArray do
Result := Result * lValue;
Result := Power(Result, 1 / Length(aArray));
end;
function HarmonicMean(aArray: TDoubleDynArray): Double;
var
lValue: Double;
begin
Result := 0;
for lValue in aArray do
Result := Result + 1 / lValue;
Result := Length(aArray) / Result;
end;
var
lSourceArray: TDoubleDynArray;
AMean, GMean, HMean: Double;
begin
lSourceArray := TDoubleDynArray.Create(1,2,3,4,5,6,7,8,9,10);
AMean := ArithmeticMean(lSourceArray));
GMean := GeometricMean(lSourceArray));
HMean := HarmonicMean(lSourceArray));
if (AMean >= GMean) and (GMean >= HMean) then
Writeln(AMean, " ≥ ", GMean, " ≥ ", HMean)
else
writeln("Error!");
end.
[edit] E
Given that we're defining all three together, it makes sense to express their regularities:
def makeMean(base, include, finish) {
return def mean(numbers) {
var count := 0
var acc := base
for x in numbers {
acc := include(acc, x)
count += 1
}
return finish(acc, count)
}
}
def A := makeMean(0, fn b,x { b+x }, fn acc,n { acc / n })
def G := makeMean(1, fn b,x { b*x }, fn acc,n { acc ** (1/n) })
def H := makeMean(0, fn b,x { b+1/x }, fn acc,n { n / acc })
? A(1..10)
# value: 5.5
? G(1..10)
# value: 4.528728688116765
? H(1..10)
# value: 3.414171521474055
[edit] Erlang
%% Author: Abhay Jain <[email protected]>
-module(mean_calculator).
-export([find_mean/0]).
find_mean() ->
%% This is function calling. First argument is the the beginning number
%% and second argument is the initial value of sum for AM & HM and initial value of product for GM.
arithmetic_mean(1, 0),
geometric_mean(1, 1),
harmonic_mean(1, 0).
%% Function to calculate Arithmetic Mean
arithmetic_mean(Number, Sum) when Number > 10 ->
AM = Sum / 10,
io:format("Arithmetic Mean ~p~n", [AM]);
arithmetic_mean(Number, Sum) ->
NewSum = Sum + Number,
arithmetic_mean(Number+1, NewSum).
%% Function to calculate Geometric Mean
geometric_mean(Number, Product) when Number > 10 ->
GM = math:pow(Product, 0.1),
io:format("Geometric Mean ~p~n", [GM]);
geometric_mean(Number, Product) ->
NewProd = Product * Number,
geometric_mean(Number+1, NewProd).
%% Function to calculate Harmonic Mean
harmonic_mean(Number, Sum) when Number > 10 ->
HM = 10 / Sum,
io:format("Harmonic Mean ~p~n", [HM]);
harmonic_mean(Number, Sum) ->
NewSum = Sum + (1/Number),
harmonic_mean(Number+1, NewSum).
Output:
Arithmetic Mean 5.5
Geometric Mean 4.528728688116765
Harmonic Mean 3.414171521474055
[edit] Euler Math Toolbox
>function A(x) := mean(x)
>function G(x) := exp(mean(log(x)))
>function H(x) := 1/mean(1/x)
>x=1:10; A(x), G(x), H(x)
5.5
4.52872868812
3.41417152147
Alternatively, e.g.,
>function G(x) := prod(x)^(1/length(x))
[edit] Euphoria
function arithmetic_mean(sequence s)
atom sum
if length(s) = 0 then
return 0
else
sum = 0
for i = 1 to length(s) do
sum += s[i]
end for
return sum/length(s)
end if
end function
function geometric_mean(sequence s)
atom p
p = 1
for i = 1 to length(s) do
p *= s[i]
end for
return power(p,1/length(s))
end function
function harmonic_mean(sequence s)
atom sum
if length(s) = 0 then
return 0
else
sum = 0
for i = 1 to length(s) do
sum += 1/s[i]
end for
return length(s) / sum
end if
end function
function true_or_false(atom x)
if x then
return "true"
else
return "false"
end if
end function
constant s = {1,2,3,4,5,6,7,8,9,10}
constant arithmetic = arithmetic_mean(s),
geometric = geometric_mean(s),
harmonic = harmonic_mean(s)
printf(1,"Arithmetic: %g\n", arithmetic)
printf(1,"Geometric: %g\n", geometric)
printf(1,"Harmonic: %g\n", harmonic)
printf(1,"Arithmetic>=Geometric>=Harmonic: %s\n",
{true_or_false(arithmetic>=geometric and geometric>=harmonic)})
Output:
Arithmetic: 5.5 Geometric: 4.52873 Harmonic: 3.41417 Arithmetic>=Geometric>=Harmonic: true
[edit] Factor
: a-mean ( seq -- mean )
[ sum ] [ length ] bi / ;
: g-mean ( seq -- mean )
[ product ] [ length recip ] bi ^ ;
: h-mean ( seq -- mean )
[ length ] [ [ recip ] map-sum ] bi / ;
( scratchpad ) 10 [1,b] [ a-mean ] [ g-mean ] [ h-mean ] tri
"%f >= %f >= %f\n" printf
5.500000 >= 4.528729 >= 3.414172
[edit] Fantom
class Main
{
static Float arithmeticMean (Int[] nums)
{
if (nums.size == 0) return 0.0f
sum := 0
nums.each |n| { sum += n }
return sum.toFloat / nums.size
}
static Float geometricMean (Int[] nums)
{
if (nums.size == 0) return 0.0f
product := 1
nums.each |n| { product *= n }
return product.toFloat.pow(1f/nums.size)
}
static Float harmonicMean (Int[] nums)
{
if (nums.size == 0) return 0.0f
reciprocals := 0f
nums.each |n| { reciprocals += 1f / n }
return nums.size.toFloat / reciprocals
}
public static Void main ()
{
items := (1..10).toList
// display results
echo (arithmeticMean (items))
echo (geometricMean (items))
echo (harmonicMean (items))
// check given relation
if ((arithmeticMean (items) >= geometricMean (items)) &&
(geometricMean (items) >= harmonicMean (items)))
echo ("relation holds")
else
echo ("relation failed")
}
}
[edit] Forth
: famean ( faddr n -- f )
0e
tuck floats bounds do
i f@ f+
float +loop
0 d>f f/ ;
: fgmean ( faddr n -- f )
1e
tuck floats bounds do
i f@ f*
float +loop
0 d>f 1/f f** ;
: fhmean ( faddr n -- f )
dup 0 d>f 0e
floats bounds do
i f@ 1/f f+
float +loop
f/ ;
create test 1e f, 2e f, 3e f, 4e f, 5e f, 6e f, 7e f, 8e f, 9e f, 10e f,
test 10 famean fdup f.
test 10 fgmean fdup fdup f.
test 10 fhmean fdup f.
( A G G H )
f>= . f>= . \ -1 -1
[edit] Fortran
program Mean
real :: a(10) = (/ (i, i=1,10) /)
real :: amean, gmean, hmean
amean = sum(a) / size(a)
gmean = product(a)**(1.0/size(a))
hmean = size(a) / sum(1.0/a)
if ((amean < gmean) .or. (gmean < hmean)) then
print*, "Error!"
else
print*, amean, gmean, hmean
end if
end program Mean
[edit] GAP
# The first two work with rationals or with floats
# (but bear in mind that support of floating point is very poor in GAP)
mean := v -> Sum(v) / Length(v);
harmean := v -> Length(v) / Sum(v, Inverse);
geomean := v -> EXP_FLOAT(Sum(v, LOG_FLOAT) / Length(v));
mean([1 .. 10]);
# 11/2
harmean([1 .. 10]);
# 25200/7381
v := List([1..10], FLOAT_INT);;
mean(v);
# 5.5
harmean(v);
# 3.41417
geomean(v);
# 4.52873
[edit] Go
package main
import (
"fmt"
"math"
)
func main() {
sum, sumr, prod := 0., 0., 1.
for n := 1.; n <= 10; n++ {
sum += n
sumr += 1 / n
prod *= n
}
a, g, h := sum/10, math.Pow(prod, .1), 10/sumr
fmt.Println("A:", a, "G:", g, "H:", h)
fmt.Println("A >= G >= H:", a >= g && g >= h)
}
- Output:
A: 5.5 G: 4.528728688116765 H: 3.414171521474055 A >= G >= H: true
[edit] Groovy
Solution:
def arithMean = { list ->
list == null \
? null \
: list.empty \
? 0 \
: list.sum() / list.size()
}
def geomMean = { list ->
list == null \
? null \
: list.empty \
? 1 \
: list.inject(1) { prod, item -> prod*item } ** (1 / list.size())
}
def harmMean = { list ->
list == null \
? null \
: list.empty \
? 0 \
: list.size() / list.collect { 1.0/it }.sum()
}
Test:
def list = 1..10
def A = arithMean(list)
def G = geomMean(list)
assert A >= G
def H = harmMean(list)
assert G >= H
println """
list: ${list}
A: ${A}
G: ${G}
H: ${H}
"""
Output:
list: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] A: 5.5 G: 4.528728688116765 H: 3.4141715214
[edit] Haskell
The general function given here yields an arithmetic mean when its first argument is 1, a geometric mean when its first argument is 0, and a harmonic mean when its first argument is -1.
import Data.List (genericLength)
import Control.Monad (zipWithM_)
mean :: Double -> [Double] -> Double
mean 0 xs = product xs ** (1 / genericLength xs)
mean p xs = (1 / genericLength xs * sum (map (** p) xs)) ** (1/p)
main = do
let ms = zipWith ((. flip mean [1..10]). (,)) "agh" [1, 0, -1]
mapM_ (\(t,m) -> putStrLn $ t : ": " ++ show m) ms
putStrLn $ " a >= g >= h is " ++ show ((\(_,[a,g,h])-> a>=g && g>=h) (unzip ms))
[edit] HicEst
AGH = ALIAS( A, G, H ) ! named vector elements
AGH = (0, 1, 0)
DO i = 1, 10
A = A + i
G = G * i
H = H + 1/i
ENDDO
AGH = (A/10, G^0.1, 10/H)
WRITE(ClipBoard, Name) AGH, "Result = " // (A>=G) * (G>=H)
! A=5.5; G=4.528728688; H=3.414171521; Result = 1;
[edit] Icon and Unicon
link numbers # for a/g/h means
procedure main()
every put(x := [], 1 to 10)
writes("x := [ "); every writes(!x," "); write("]")
write("Arithmetic mean:", a := amean!x)
write("Geometric mean:",g := gmean!x)
write("Harmonic mean:", h := hmean!x)
write(" a >= g >= h is ", if a >= g >= h then "true" else "false")
end
numbers:amean, numbers:gmean, and numbers:hmean are shown below:
procedure amean(L[]) #: arithmetic mean
local m
if *L = 0 then fail
m := 0.0
every m +:= !L
return m / *L
end
procedure gmean(L[]) #: geometric mean
local m
if *L = 0 then fail
m := 1.0
every m *:= !L
m := abs(m)
if m > 0.0 then
return exp (log(m) / *L)
else
fail
end
procedure hmean(L[]) #: harmonic mean
local m, r
if *L = 0 then fail
m := 0.0
every r := !L do {
if r = 0.0 then fail
else m +:= 1.0 / r
}
return *L / m
end
Sample output:
#means.exe x := [ 1 2 3 4 5 6 7 8 9 10 ] Arithmetic mean:5.5 Geometric mean:4.528728688116765 Harmonic mean:3.414171521474055 a >= g >= h is true
[edit] J
Solution:
amean=: +/ % #
gmean=: # %: */
hmean=: amean&.:%
Example Usage:
(amean , gmean , hmean) >: i. 10
5.5 4.528729 3.414172
assert 2 >:/\ (amean , gmean , hmean) >: i. 10 NB. check amean >= gmean and gmean >= hmean
Note that gmean could have instead been defined as mean under logarithm, for example:
gmean=:amean&.:^.
[edit] Java
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));
}
}
Output:
A = 5.500000 G = 4.528729 H = 3.414172 A >= G is true, G >= H is true
[edit] JavaScript
,function arithmetic_mean(ary) {
var sum = ary.reduce(function(s,x) {return (s+x)}, 0);
return (sum / ary.length);
}
function geometic_mean(ary) {
var product = ary.reduce(function(s,x) {return (s*x)}, 1);
return Math.pow(product, 1/ary.length);
}
function harmonic_mean(ary) {
var sum_of_inv = ary.reduce(function(s,x) {return (s + 1/x)}, 0);
return (ary.length / sum_of_inv);
}
var ary = [1,2,3,4,5,6,7,8,9,10];
var A = arithmetic_mean(ary);
var G = geometic_mean(ary);
var H = harmonic_mean(ary);
print("is A >= G >= H ? " + (A >= G && G >= H ? "yes" : "no"));
[edit] Liberty BASIC
for i = 1 to 10
a = a + i
next
ArithmeticMean = a/10
b = 1
for i = 1 to 10
b = b * i
next
GeometricMean = b ^ (1/10)
for i = 1 to 10
c = c + (1/i)
next
HarmonicMean = 10/c
print "ArithmeticMean: ";ArithmeticMean
print "Geometric Mean: ";GeometricMean
print "Harmonic Mean: ";HarmonicMean
if (ArithmeticMean>=GeometricMean) and (GeometricMean>=HarmonicMean) then
print "True"
else
print "False"
end if
[edit] Logo
to compute_means :count
local "sum
make "sum 0
local "product
make "product 1
local "reciprocal_sum
make "reciprocal_sum 0
repeat :count [
make "sum sum :sum repcount
make "product product :product repcount
make "reciprocal_sum sum :reciprocal_sum (quotient repcount)
]
output (sentence (quotient :sum :count) (power :product (quotient :count))
(quotient :count :reciprocal_sum))
end
make "means compute_means 10
print sentence [Arithmetic mean is] item 1 :means
print sentence [Geometric mean is] item 2 :means
print sentence [Harmonic mean is] item 3 :means
bye
[edit] Lua
function fsum(f, a, ...) return a and f(a) + fsum(f, ...) or 0 end
function pymean(t, f, finv) return finv(fsum(f, unpack(t)) / #t) end
nums = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
--arithmetic
a = pymean(nums, function(n) return n end, function(n) return n end)
--geometric
g = pymean(nums, math.log, math.exp)
--harmonic
h = pymean(nums, function(n) return 1/n end, function(n) return 1/n end)
print(a, g, h)
assert(a >= g and g >= h)
[edit] Mathematica
Print["{Arithmetic Mean, Geometric Mean, Harmonic Mean} = ",
N@Through[{Mean, GeometricMean, HarmonicMean}[Range@10]]]
Solution:
{Arithmetic Mean, Geometric Mean, Harmonic Mean} = {5.5,4.52873,3.41417}
[edit] MATLAB
function [A,G,H] = pythagoreanMeans(list)
A = mean(list);
G = geomean(list);
H = harmmean(list);
end
A solution that works for both, Matlab and Octave, is this
function [A,G,H] = pythagoreanMeans(list)
A = mean(list); % arithmetic mean
G = exp(mean(log(list))); % geometric mean
H = 1./mean(1./list); % harmonic mean
end
Solution:
>> [A,G,H]=pythagoreanMeans((1:10))
A =
5.500000000000000
G =
4.528728688116765
H =
3.414171521474055
[edit] Maxima
/* built-in */
L: makelist(i, i, 1, 10)$
mean(L), numer; /* 5.5 */
geometric_mean(L), numer; /* 4.528728688116765 */
harmonic_mean(L), numer; /* 3.414171521474055 */
[edit] MUMPS
Pyth(n) New a,ii,g,h,x
For ii=1:1:n set x(ii)=ii
;
; Average
Set a=0 For ii=1:1:n Set a=a+x(ii)
Set a=a/n
;
; Geometric
Set g=1 For ii=1:1:n Set g=g*x(ii)
Set g=g**(1/n)
;
; Harmonic
Set h=0 For ii=1:1:n Set h=1/x(ii)+h
Set h=n/h
;
Write !,"Pythagorean means for 1..",n,":",!
Write "Average = ",a," >= Geometric ",g," >= harmonic ",h,!
Quit
Do Pyth(10)
Pythagorean means for 1..10:
Average = 5.5 >= Geometric 4.528728688116178495 >= harmonic 3.414171521474055006
[edit] NetRexx
/* NetRexx */
options replace format comments java crossref symbols nobinary
numeric digits 20
a1 = ArrayList(Arrays.asList([Rexx 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0]))
say "Arithmetic =" arithmeticMean(a1)", Geometric =" geometricMean(a1)", Harmonic =" harmonicMean(a1)
return
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method arithmeticMean(numbers = java.util.List) public static returns Rexx
-- somewhat arbitrary return for ooRexx
if numbers.isEmpty then return "NaN"
mean = 0
number = Rexx
loop number over numbers
mean = mean + number
end
return mean / numbers.size
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method geometricMean(numbers = java.util.List) public static returns Rexx
-- somewhat arbitrary return for ooRexx
if numbers.isEmpty then return "NaN"
mean = 1
number = Rexx
loop number over numbers
mean = mean * number
end
return Math.pow(mean, 1 / numbers.size)
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
method harmonicMean(numbers = java.util.List) public static returns Rexx
-- somewhat arbitrary return for ooRexx
if numbers.isEmpty then return "NaN"
mean = 0
number = Rexx
loop number over numbers
if number = 0 then return "Nan"
mean = mean + (1 / number)
end
-- problem here...
return numbers.size / mean
Output:
Arithmetic = 5.5, Geometric = 4.528728688116765, Harmonic = 3.4141715214740550062
[edit] Oberon-2
Oxford Oberon-2
MODULE PythMean;
IMPORT Out, ML := MathL;
PROCEDURE Triplets(a: ARRAY OF INTEGER;VAR triplet: ARRAY OF LONGREAL);
VAR
i: INTEGER;
BEGIN
triplet[0] := 0.0;triplet[1] := 0.0; triplet[2] := 0.0;
FOR i:= 0 TO LEN(a) - 1 DO
triplet[0] := triplet[0] + a[i];
triplet[1] := triplet[1] + ML.Ln(a[i]);
triplet[2] := triplet[2] + (1 / a[i])
END
END Triplets;
PROCEDURE Means*(a: ARRAY OF INTEGER);
VAR
triplet: ARRAY 3 OF LONGREAL;
BEGIN
Triplets(a,triplet);
Out.String("A(1 .. 10): ");Out.LongReal(triplet[0] / LEN(a));Out.Ln;
Out.String("G(1 .. 10): ");Out.LongReal(ML.Exp(triplet[1]/ LEN(a)));Out.Ln;
Out.String("H(1 .. 10): ");Out.LongReal(LEN(a) / triplet[2]);Out.Ln;
END Means;
VAR
nums: ARRAY 10 OF INTEGER;
i: INTEGER;
BEGIN
FOR i := 0 TO LEN(nums) - 1 DO
nums[i] := i + 1
END;
Means(nums)
END PythMean.
Output:
A(1 .. 10): 5.50000000000 G(1 .. 10): 4.52872868812 H(1 .. 10): 3.41417152147
[edit] OCaml
The three means in one function
let means v =
let n = Array.length v
and a = ref 0.0
and b = ref 1.0
and c = ref 0.0 in
for i=0 to n-1 do
a := !a +. v.(i);
b := !b *. v.(i);
c := !c +. 1.0/.v.(i);
done;
let nn = float_of_int n in
(!a /. nn, !b ** (1.0/.nn), nn /. !c)
;;
Sample output:
means (Array.init 10 (function i -> (float_of_int (i+1)))) ;;
(* (5.5, 4.5287286881167654, 3.4141715214740551) *)
Another implementation using Array.fold_left instead of a for loop:
let means v =
let (a, b, c) =
Array.fold_left
(fun (a, b, c) x -> (a+.x, b*.x, c+.1./.x))
(0.,1.,0.) v
in
let n = float_of_int (Array.length v) in
(a /. n, b ** (1./.n), n /. c)
;;
[edit] Octave
A = mean(list); % arithmetic mean
G = mean(list,'g'); % geometric mean
H = mean(list,'a'); % harmonic mean
See also Matlab implementation #MATLAB
[edit] ooRexx
a = .array~of(1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0)
say "Arithmetic =" arithmeticMean(a)", Geometric =" geometricMean(a)", Harmonic =" harmonicMean(a)
::routine arithmeticMean
use arg numbers
-- somewhat arbitrary return for ooRexx
if numbers~isEmpty then return "NaN"
mean = 0
loop number over numbers
mean += number
end
return mean / numbers~items
::routine geometricMean
use arg numbers
-- somewhat arbitrary return for ooRexx
if numbers~isEmpty then return "NaN"
mean = 1
loop number over numbers
mean *= number
end
return rxcalcPower(mean, 1 / numbers~items)
::routine harmonicMean
use arg numbers
-- somewhat arbitrary return for ooRexx
if numbers~isEmpty then return "NaN"
mean = 0
loop number over numbers
if number = 0 then return "Nan"
mean += 1 / number
end
-- problem here....
return numbers~items / mean
::requires rxmath LIBRARY
[edit] Oz
declare
%% helpers
fun {Sum Xs} {FoldL Xs Number.'+' 0.0} end
fun {Product Xs} {FoldL Xs Number.'*' 1.0} end
fun {Len Xs} {Int.toFloat {Length Xs}} end
fun {AMean Xs}
{Sum Xs}
/
{Len Xs}
end
fun {GMean Xs}
{Pow
{Product Xs}
1.0/{Len Xs}}
end
fun {HMean Xs}
{Len Xs}
/
{Sum {Map Xs fun {$ X} 1.0 / X end}}
end
Numbers = {Map {List.number 1 10 1} Int.toFloat}
[A G H] = [{AMean Numbers} {GMean Numbers} {HMean Numbers}]
in
{Show [A G H]}
A >= G = true
G >= H = true
[edit] PARI/GP
General implementations:
arithmetic(v)={
sum(i=1,#v,v[i])/#v
};
geometric(v)={
prod(i=1,#v,v[i])^(1/#v)
};
harmonic(v)={
#v/sum(i=1,#v,1/v[i])
};
v=vector(10,i,i);
[arithmetic(v),geometric(v),harmonic(v)]
Specific to the first n positive integers:
arithmetic_first(n)={
(n+1)/2
};
geometric_first(n)={
n!^(1/n)
};
harmonic_first(n)={
n/if(n>1000,
log(n)+Euler+1/(n+n)+1/(12*n^2)-1/(120*n^4)+1/(252*n^6)-1/(240*n^8)+1/(132*n^10)
,
n/sum(k=1,n,1/k)
)
};
[arithmetic_first(10),geometric_first(10),harmonic_first(10)]
%[1]>=%[2] && %[2] >= %[3]
These are, asymptotically, n/2, n/e, and n/log n.
[edit] Pascal
See Delphi
[edit] Perl
sub A
{
my $a = 0;
$a += $_ for @_;
return $a / @_;
}
sub G
{
my $p = 1;
$p *= $_ for @_;
return $p**(1/@_); # power of 1/n == root of n
}
sub H
{
my $h = 0;
$h += 1/$_ for @_;
return @_/$h;
}
my @ints = (1..10);
my $a = A(@ints);
my $g = G(@ints);
my $h = H(@ints);
print "A=$a\nG=$g\nH=$h\n";
die "Error" unless $a >= $g and $g >= $h;
[edit] Perl 6
sub A(@x) { ([+] @x) / @x.elems }
sub G(@x) { ([*] @x) ** (1 / @x.elems) }
sub H(@x) { @x.elems / [+] @x.map: 1/* }
say "A(1,...,10) = ", A(1..10);
say "G(1,...,10) = ", G(1..10);
say "H(1,...,10) = ", H(1..10);
Output:
A(1,...,10) = 5.5 G(1,...,10) = 4.52872868811677 H(1,...,10) = 3.41417152147406
[edit] PL/I
declare n fixed binary,
(Average, Geometric, Harmonic) float;
declare A(10) float static initial (1,2,3,4,5,6,7,8,9,10);
n = hbound(A,1);
/* compute the average */
Average = sum(A)/n;
/* Compute the geometric mean: */
Geometric = prod(A)**(1/n);
/* Compute the Harmonic mean: */
Harmonic = n / sum(1/A);
put skip data (Average);
put skip data (Geometric);
put skip data (Harmonic);
if Average < Geometric then put skip list ('Error');
if Geometric < Harmonic then put skip list ('Error');
Results:
AVERAGE= 5.50000E+0000; GEOMETRIC= 4.52873E+0000; HARMONIC= 3.41417E+0000;
[edit] PicoLisp
(load "@lib/math.l")
(let (Lst (1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0) Len (length Lst))
(prinl "Arithmetic mean: "
(format
(/ (apply + Lst) Len)
*Scl ) )
(prinl "Geometric mean: "
(format
(pow (*/ (apply * Lst) (** 1.0 (dec Len))) (/ 1.0 Len))
*Scl ) )
(prinl "Harmonic mean: "
(format
(*/ (* 1.0 Len) 1.0 (sum '((N) (*/ 1.0 1.0 N)) Lst))
*Scl ) ) )
Output:
Arithmetic mean: 5.500000 Geometric mean: 4.528729 Harmonic mean: 3.414172
[edit] PostScript
/pythamean{
/x exch def
/sum 0 def
/prod 1 def
/invsum 0 def
/i 1 def
x{
/sum sum i add def
/prod prod i mul def
/invsum invsum i -1 exp add def
/i i 1 add def
}repeat
(Arithmetic Mean : ) print
sum x div =
(Geometric Mean : ) print
prod x -1 exp exp =
(Harmonic Mean : ) print
x invsum div =
}def
10 pythamean
Output :
Arithmetic Mean : 5.5
Geometric Mean : 4.52873
Harmonic Mean : 3.41417
/numbers {[1 10] 1 range}.
/recip {1 exch div}.
% Arithmetic mean
numbers dup 0 {+} fold exch length div
% Geometric mean
numbers dup 1 {*} fold exch length recip exp
% Harmonic mean
numbers dup 0 {recip +} fold exch length exch div
[edit] PowerShell
$A = 0
$LogG = 0
$InvH = 0
$ii = 1..10
foreach($i in $ii) {
# Arithmetic mean is computed directly
$A += $i / $ii.Count
# Geometric mean is computed using Logarithms
$LogG += [Math]::Log($i) / $ii.Count
# Harmonic mean is computed using its inverse
$InvH += 1 / ($i * $ii.Count)
}
$G = [Math]::Exp($LogG)
$H = 1/$InvH
write-host "Arithmetic mean: A = $A"
write-host "Geometric mean: G = $G"
write-host "Harmonic mean: H = $H"
write-host "Is A >= G ? $($A -ge $G)"
write-host "Is G >= H ? $($G -ge $H)"
Output:
Arithmetic mean: A = 5.5 Geometric mean: G = 4.52872868811676 Harmonic mean: H = 3.41417152147405 Is A >= G ? True Is G >= H ? True
[edit] PureBasic
Procedure.d ArithmeticMean()
For a = 1 To 10
mean + a
Next
ProcedureReturn mean / 10
EndProcedure
Procedure.d GeometricMean()
mean = 1
For a = 1 To 10
mean * a
Next
ProcedureReturn Pow(mean, 1 / 10)
EndProcedure
Procedure.d HarmonicMean()
For a = 1 To 10
mean.d + 1 / a
Next
ProcedureReturn 10 / mean
EndProcedure
If HarmonicMean() <= GeometricMean() And GeometricMean() <= ArithmeticMean()
Debug "true"
EndIf
Debug ArithmeticMean()
Debug GeometricMean()
Debug HarmonicMean()
[edit] Python
from operator import mul
from functools import reduce
def amean(num):
return sum(num)/len(num)
def gmean(num):
return reduce(mul, num, 1)**(1/len(num))
def hmean(num):
return len(num)/sum(1/n for n in num)
numbers = range(1,11) # 1..10
a, g, h = amean(numbers), gmean(numbers), hmean(numbers)
print(a, g, h)
assert( a >= g >= h )
Output:
5.5 4.52872868812 3.41417152147
These are the same in Python 2 apart from requiring explicit float division (either through float() casts or float literals such as 1./n); or better, do a from __future__ import division, which works on Python 2.2+ as well as Python 3, and makes division work consistently like it does in Python 3.
[edit] R
Initialise x
x <- 1:10
Arithmetic mean
a <- sum(x)/length(x)
or
a <- mean(x)
The geometric mean
g <- prod(x)^(1/length(x))
The harmonic mean (no error checking that 
)
h <- length(x)/sum(1/x)
Then:
a > g
and
g > h
give both
[1] TRUE
[edit] Racket
#lang racket
(define (arithmetic xs)
(/ (for/sum ([x xs]) x)
(length xs)))
(define (geometric xs)
(expt (for/product ([x xs]) x)
(/ (length xs))))
(define (harmonic xs)
(/ (length xs)
(for/sum ([x xs]) (/ x))))
(define xs (range 1 11))
(arithmetic xs)
(geometric xs)
(harmonic xs)
(>= (arithmetic xs) (geometric xs) (harmonic xs))
Output:
5 1/2 4.528728688116765 3 3057/7381 #t
[edit] REXX
REXX doesn't have a POW function, so an IROOT (integer root) function is included here.
Coding note: while the DO loop flow looks nice, it took a bit of work to get exactly right,
and doesn't lend itself to being updated easily.
/*REXX program to compute/show Pythagorean means [Amean, Gmean, Hmean].*/
parse arg n . /*maybe get an optional argument.*/
if n=='' then n=10 /*None specified? Assume default*/
/*══════════════════compute Amean [Arithmetic mean]*/
sum=0; do j=1 for n
@.j=j /*populate the stemmed array @. */
sum=sum+@.j /*compute the sum of all elements*/
end /*j*/
Amean=sum/n /*calculate the Amean. */
say 'Amean =' Amean /*show and tell Amean. */
/*══════════════════compute Gmean [Geometric mean].*/
prod=1; do k=1 for n
prod=prod*@.k /*comp. product of all elements. */
end /*k*/
Gmean=iroot(prod,n) /*calculate the Gmean. */
say 'Gmean =' Gmean /*show and tell Gmean. */
/*══════════════════compute Hmean [Harmonic mean]. */
rsum=0; do m=1 for n
rsum=rsum+1/@.m /*compute the sum of reciprocals.*/
end /*m*/
Hmean=n/rsum /*calculate the Hmean. */
say 'Hmean =' Hmean /*show and tell Hmean. */
exit /*stick a fork in it, we're done.*/
/*──────────────────────────────────IROOT subroutine────────────────────*/
iroot: procedure; arg x 1 ox,y 1 oy /*get both args, and also a copy.*/
if x=0 | x=1 then return x /*handle special case of 0 & 1. */
if y=0 then return 1 /*handle special case of root 0. */
if y=1 then return x /*handle special case of root 1. */
if x<0 & y//2==0 then do /*check for illegal combination. */
say; say '*** error! *** (from IROOT):'; say
say 'root' y "can't be even if 1st argument is < 0."
say; return '[n/a]' /*return a not applicable.*/
end
x=abs(x) /*use the absolute value for X. */
y=abs(y) /*use the absolute value for root*/
digO=digits() /*save original accuracy (digits)*/
a=digO+5 /*use an extra 5 digs (accuracy).*/
g=(x+1)/y**y /*use this as the 1st guesstimate*/
m=y-1 /*use this as a fast [root-1]. */
numeric fuzz 3 /*3 fuzz digits for comparisons. */
d=5 /*start with 5 digits accuracy. When the */
/*DIGITS is large, CPU time is wasted on */
/*large accuracies when the guess isn't */
/*close to the final answer. It's best to*/
/*take baby steps before going full bore */
/*throttle and putting the pedal to the */
/*metal, getting it in high gear, and */
/*then turning the volume all the way up. */
do forever /* ◄─────────────────┐ keep plugging as digs increases*/
d=min(d+d,a) /* │ limit the digits to orig digs┐5*/
numeric digits d /* │ keep increasing the accuracy. */
old=0 /* │ define old (guess). */
/* │ */
do forever /* ◄────────────┐ │ keep plugging at the Yth root.*/
_=(m*g**y+x)/y/g**m /* │ │ this is the nitty-gritty stuff.*/
if _=g | _=old then leave /* │ │ are we close enough yet ? */
old=g /* │ │ save guess in old (guess). */
g=_ /* │ │ set Guess to what's been calc. */
end /*forever ►────────────┘ │ */
/* │ */
if d==a then leave /* │ are we at the desired accuracy?*/
end /*forever ►───────────────┘ */
_=g*sign(ox) /*adjust for the sign of orig X. */
if oy<0 then _=1/_ /*adjust for negative root. */
numeric digits digO /*restore the original digits. */
return _/1 /*normalize result to orig digits*/
output
Amean = 5.5 Gmean = 4.52872869 Hmean = 3.41417153
[edit] Ruby
class Array
def arithmetic_mean
inject(:+).to_f / length
end
def geometric_mean
inject(:*) ** (1.0 / length)
end
def harmonic_mean
length.to_f / inject(0) {|s, m| s += 1.0/m}
end
end
class Range
def method_missing(m, *args)
case m
when /_mean$/ then to_a.send(m)
else super
end
end
end
p a = (1..10).arithmetic_mean
p g = (1..10).geometric_mean
p h = (1..10).harmonic_mean
# is h < g < a ??
p g.between?(h, a)
outputs
5.5 4.52872868811677 3.41417152147406 true
[edit] Run BASIC
bXsum = 1
for i = 1 to 10
sum = sum + i ' sum of 1 -> 10
bXsum = bXsum * i ' sum i * i
sum1i = sum1i + (1/i) ' sum 1/i
next
average = sum / 10
geometric = bXsum ^ (1/10)
harmonic = 10/sum1i
print "ArithmeticMean:";average
print "Geometric Mean:";geometric
print " Harmonic Mean:";harmonic
if (average >= geometric) and (geometric >= harmonic) then print "True" else print "False"
Output:
Arithmetic Mean:5.5 Geometric Mean:4.52872869 Harmonic Mean:3.41417132 True
[edit] Scala
def arithmeticMean(n: Seq[Int]) = n.sum / n.size.toDouble
def geometricMean(n: Seq[Int]) = math.pow(n.foldLeft(1.0)(_*_), 1.0 / n.size.toDouble)
def harmonicMean(n: Seq[Int]) = n.size / n.map(1.0 / _).sum
var nums = 1 to 10
var a = arithmeticMean(nums)
var g = geometricMean(nums)
var h = harmonicMean(nums)
println("Arithmetic mean " + a)
println("Geometric mean " + g)
println("Harmonic mean " + h)
assert(a >= g && g >= h)
[edit] Scheme
(define (a-mean l)
(/ (apply + l) (length l)))
(define (g-mean l)
(expt (apply * l) (/ (length l))))
(define (h-mean l)
(/ (length l) (apply + (map / l))))
(define (iota start stop)
(if (> start stop)
(list)
(cons start (iota (+ start 1) stop))))
(let* ((l (iota 1 10)) (a (a-mean l)) (g (g-mean l)) (h (h-mean l)))
(display a)
(display " >= ")
(display g)
(display " >= ")
(display h)
(newline)
(display (>= a g h))
(newline))
Output:
11/2 >= 4.528728688116765 >= 25200/7381
#t
[edit] Seed7
$ include "seed7_05.s7i";
include "float.s7i";
const array float: numbers is [] (1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0);
const func proc: main is func
local
var float: number is 0.0;
var float: sum is 0.0;
var float: product is 1.0;
var float: reciprocalSum is 0.0;
begin
for number range numbers do
sum +:= number;
product *:= number;
reciprocalSum +:= 1.0 / number;
end for;
writeln("Arithmetic mean: " <& sum / flt(length(numbers)));
writeln("Geometric mean: " <& product ** (1.0 / flt(length(numbers))));
writeln("Harmonic mean: " <& flt(length(numbers)) / reciprocalSum);
end func;
Output:
Arithmetic mean: 5.5 Geometric mean: 4.528728961944580078125 Harmonic mean: 3.4141712188720703125
[edit] Smalltalk
This extends the class Collection, so these three methods can be called over any kind of collection, it is enough the the objects of the collection understand +, *, raisedTo, reciprocal and /.
Collection extend
[
arithmeticMean
[
^ (self fold: [:a :b| a + b ]) / (self size)
]
geometricMean
[
^ (self fold: [:a :b| a * b]) raisedTo: (self size reciprocal)
]
harmonicMean
[
^ (self size) / ((self collect: [:x|x reciprocal]) fold: [:a :b| a + b ] )
]
]
|a|
a := #(1 2 3 4 5 6 7 8 9 10).
a arithmeticMean asFloat displayNl.
a geometricMean asFloat displayNl.
a harmonicMean asFloat displayNl.
((a arithmeticMean) >= (a geometricMean)) displayNl.
((a geometricMean) >= (a harmonicMean)) displayNl.
Output:
5.5 4.528728688116765 3.414171521474055 true true
[edit] Tcl
proc arithmeticMean list {
set sum 0.0
foreach value $list { set sum [expr {$sum + $value}] }
return [expr {$sum / [llength $list]}]
}
proc geometricMean list {
set product 1.0
foreach value $list { set product [expr {$product * $value}] }
return [expr {$product ** (1.0/[llength $list])}]
}
proc harmonicMean list {
set sum 0.0
foreach value $list { set sum [expr {$sum + 1.0/$value}] }
return [expr {[llength $list] / $sum}]
}
set nums {1 2 3 4 5 6 7 8 9 10}
set A10 [arithmeticMean $nums]
set G10 [geometricMean $nums]
set H10 [harmonicMean $nums]
puts "A10=$A10, G10=$G10, H10=$H10"
if {$A10 >= $G10} { puts "A10 >= G10" }
if {$G10 >= $H10} { puts "G10 >= H10" }
Output:
A10=5.5, G10=4.528728688116765, H10=3.414171521474055 A10 >= G10 G10 >= H10
[edit] Ursala
#import std
#import flo
data = ari10(1.,10.) # arithmetic progression, length 10 with endpoints 1 and 10
a = mean data
g = exp mean ln* data
h = div/1. mean div/*1. data
#cast %eLbX
main = ^(~&,ordered not fleq) <a,g,h>
output:
( <5.500000e+00,4.528729e+00,3.414172e+00>, true)
[edit] Vala
Most valac setups will need "-X -lm" added to the compile command to include the C math library.
double arithmetic(int[] list){
double mean;
double sum = 0;
foreach(int number in list){
sum += number;
} // foreach
mean = sum / list.length;
return mean;
} // end arithmetic mean
double geometric(int[] list){
double mean;
double product = 1;
foreach(int number in list){
product *= number;
} // foreach
mean = Math.pow(product, (1 / (double) list.length));
return mean;
} // end geometric mean
double harmonic(int[] list){
double mean;
double sum_inverse = 0;
foreach(int number in list){
sum_inverse += (1 / (double) number);
} // foreach
mean = (double) list.length / sum_inverse;
return mean;
} // end harmonic mean
public static void main(){
int[] list = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
double arithmetic_mean = arithmetic(list);
double geometric_mean = geometric(list);
double harmonic_mean = harmonic(list);
// should be 5.5
stdout.printf("Arithmetic mean: %s\n", arithmetic_mean.to_string());
// should be 4.528728688116765
stdout.printf("Geometric mean: %s\n", geometric_mean.to_string());
// should be 4.528728688116765
stdout.printf("Harmonic mean: %s\n", harmonic_mean.to_string());
}
Output:
Arithmetic mean: 5.5 Geometric mean: 4.5287286881167654 Harmonic mean: 3.4141715214740551
[edit] XPL0
include c:\cxpl\codes;
func real Power(X, Y); \X raised to the Y power
real X, Y; \ (from StdLib.xpl)
return Exp(Y * Ln(X));
int N, Order;
real R, A, A1, G, G1, H, H1;
[A1:= 0.0; G1:= 1.0; H1:= 0.0;
Order:= true;
for N:= 1 to 10 do
[R:= float(N); \convert integer N to real R
A1:= A1 + R;
A:= A1/R; \arithmetic mean
G1:= G1 * R;
G:= Power(G1, 1.0/R); \geometric mean (Nth root of G1)
if G>A then Order:= false;
H1:= H1 + 1.0/R;
H:= R/H1; \harmonic mean
if H>G then Order:= false;
];
RlOut(0, A); CrLf(0);
RlOut(0, G); CrLf(0);
RlOut(0, H); CrLf(0);
if not Order then Text(0, "NOT ");
Text(0, "ALWAYS DECREASING ORDER
");
]
Output:
5.50000
4.52873
3.41417
ALWAYS DECREASING ORDER
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