Open in App
Not now

# Program for harmonic mean of numbers

• Last Updated : 17 Feb, 2023

Given an array of elements, find harmonic mean of numbers.
Examples:

```Input : arr[] = {2.0, 1.0}
Output : 1.3333
Harmonic mean = 2/(1/2.0 + 1/1.0)
= (2 * 2)/3
= 1.333

Input : arr[] = {13.5, 14.5, 14.8, 15.2, 16.1}
Output : 14.7707```

Harmonic mean is used when average of rates is required, below is the formula.
Harmonic mean of n numbers x1, x2
x3, . . ., xn can written as below.
Harmonic mean = n / ((1/x1) + (1/x2) + (1/x3) + . . . + (1/xn))

Below is the implementation of Harmonic Mean.

## C++

 `// CPP program to find harmonic mean of numbers. ` `#include ` `using` `namespace` `std; ` ` `  `// Function that returns harmonic mean. ` `float` `harmonicMean(``float` `arr[], ``int` `n) ` `{ ` `    ``// Declare sum variables and initialize with zero. ` `    ``float` `sum = 0; ` `    ``for` `(``int` `i = 0; i < n; i++) ` `        ``sum = sum + (``float``)1 / arr[i]; ` `    ``return` `(``float``)n / sum; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``float` `arr[] = { 13.5, 14.5, 14.8, 15.2, 16.1 }; ` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]); ` `    ``cout << harmonicMean(arr, n); ` `    ``return` `0; ` `} ` ` `  `// This code is contributed by Aditya Kumar (adityakumar129)`

## C

 `// C program to find harmonic mean of numbers. ` `#include ` ` `  `// Function that returns harmonic mean. ` `float` `harmonicMean(``float` `arr[], ``int` `n) ` `{ ` `    ``// Declare sum variables and initialize with zero. ` `    ``float` `sum = 0; ` `    ``for` `(``int` `i = 0; i < n; i++) ` `        ``sum = sum + (``float``)1 / arr[i]; ` `    ``return` `(``float``)n / sum; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``float` `arr[] = { 13.5, 14.5, 14.8, 15.2, 16.1 }; ` `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr[0]); ` `    ``printf``(``"%f"``,harmonicMean(arr, n)); ` `    ``return` `0; ` `} ` ` `  `// This code is contributed by Aditya Kumar (adityakumar129)`

## Java

 `// JAVA program to find harmonic mean of numbers. ` `import` `java.io.*; ` ` `  `class` `GFG { ` ` `  `    ``// Function that returns harmonic mean. ` `    ``static` `float` `harmonicMean(``float` `arr[], ``int` `n) ` `    ``{ ` `        ``// Declare sum variables and initialize with zero ` `        ``float` `sum = ``0``; ` `        ``for` `(``int` `i = ``0``; i < n; i++) ` `            ``sum = sum + (``float``)``1` `/ arr[i]; ` `        ``return` `(``float``)n / sum; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `main(String args[]) ` `    ``{ ` `        ``float` `arr[] = { ``13``.5f, ``14``.5f, ``14``.8f, ``15``.2f, ``16``.1f }; ` `        ``int` `n = arr.length; ` `        ``System.out.println(harmonicMean(arr, n)); ` `    ``} ` `} ` ` `  `// This code is contributed by Aditya Kumar (adityakumar129)`

## Python3

 `# Python 3 program to find harmonic ` `# mean of numbers. ` ` `  `# Function that returns harmonic mean. ` `def` `harmonicMean(arr, n) : ` `   `  `    ``# Declare sum variables and  ` `    ``# initialize with zero. ` `    ``sm ``=` `0` `    ``for` `i ``in` `range``(``0``, n) : ` `        ``sm ``=` `sm ``+` `(``1``) ``/` `arr[i]; ` `  `  `    ``return` `n ``/` `sm ` ` `  ` `  `# Driver code ` `arr ``=` `[ ``13.5``, ``14.5``, ``14.8``, ``15.2``, ``16.1` `]; ` `n ``=` `len``(arr) ` `print``(harmonicMean(arr, n)) ` ` `  `# This code is contributed by Nikita Tiwari. `

## C#

 `// C# program to find harmonic ` `// mean of numbers. ` `using` `System; ` ` `  `class` `GFG { ` ` `  `    ``// Function that returns harmonic mean. ` `    ``static` `float` `harmonicMean(``float``[] arr, ``int` `n) ` `    ``{ ` `        ``// Declare sum variables and ` `        ``// initialize with zero ` `        ``float` `sum = 0; ` `        ``for` `(``int` `i = 0; i < n; i++) ` `            ``sum = sum + (``float``)1 / arr[i]; ` ` `  `        ``return` `(``float``)n / sum; ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``float``[] arr = { 13.5f, 14.5f, 14.8f, ` `                        ``15.2f, 16.1f }; ` `        ``int` `n = arr.Length; ` `        ``Console.WriteLine(harmonicMean(arr, n)); ` `    ``} ` `} ` ` `  `/*This code is contributed by vt_m.*/`

## PHP

 ` `

## Javascript

 ``

Output:

`14.7707`

Time Complexity: O(n)

Auxiliary Space: O(1), since no extra space has been taken.
What if we are given elements and their frequencies?
If we are given n numbers and every number has some frequency then simply we use formula
Harmonic mean = (Frequency-Sum) /((f1/x1) + (f2/x2) + (f3/x3) + . . . + (fn/xn))
Where f1, f2, f3, . . ., fn are the frequencies of elements and x1, 2, x3, . . ., xn are the elements of array.
Frequency-Sum = f1 + f2 + f3, . . ., fn
Examples:

```Input : num[] = {13, 14, 15, 16, 17}
freq[] = {2, 5, 13, 7, 3}
Output : 15.0631```

## C++

 `// C++ program to find harmonic mean. ` `#include ` `using` `namespace` `std; ` `// Function that returns harmonic mean. ` `float` `harmonicMean(``int` `arr[], ``int` `freq[], ``int` `n) ` `{ ` `    ``float` `sum = 0, frequency_sum = 0; ` `    ``for` `(``int` `i = 0; i < n; i++) { ` `        ``sum = sum + (``float``)freq[i] / arr[i]; ` `        ``frequency_sum  = frequency_sum  + freq[i]; ` `    ``} ` `    ``return` `frequency_sum / sum; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `num[] = { 13, 14, 15, 16, 17 }; ` `    ``int` `freq[] = { 2, 5, 13, 7, 3 }; ` `    ``int` `n = ``sizeof``(num) / ``sizeof``(num[0]); ` `    ``cout << harmonicMean(num, freq, n); ` `    ``return` `0; ` `} `

## Java

 `// JAVA program to find harmonic mean. ` ` `  `class` `GFG { ` `     `  `    ``// Function that returns harmonic mean. ` `    ``static` `float` `harmonicMean(``int` `arr[], ``int` `freq[], ` `                              ``int` `n) ` `    ``{ ` `        ``float` `sum = ``0``, frequency_sum = ``0``; ` `        ``for` `(``int` `i = ``0``; i < n; i++) { ` `            ``sum = sum + (``float``)freq[i] / arr[i]; ` `            ``frequency_sum  = frequency_sum  + freq[i]; ` `        ``} ` `        ``return` `(frequency_sum / sum); ` `    ``} ` `      `  `    ``// Driver code ` `    ``public` `static` `void` `main(String args[]) ` `    ``{ ` `        ``int` `num[] = { ``13``, ``14``, ``15``, ``16``, ``17` `}; ` `        ``int` `freq[] = { ``2``, ``5``, ``13``, ``7``, ``3` `}; ` `        ``int` `n = num.length; ` `        ``System.out.println(harmonicMean(num, freq, n)); ` `    ``} ` `} ` ` `  `/*This code is contributed by Nikita Tiwari.*/`

## Python3

 `# Python 3 program to find harmonic mean. ` ` `  `# Function that returns harmonic mean. ` `def` `harmonicMean(arr, freq, n) : ` `    ``sm ``=` `0` `    ``frequency_sum ``=` `0` `    ``for` `i ``in` `range``(``0``,n) : ` `        ``sm ``=` `sm ``+` `freq[i] ``/` `arr[i] ` `        ``frequency_sum  ``=` `frequency_sum  ``+` `freq[i] ` `     `  `    ``return` `(``round``(frequency_sum ``/` `sm,``4``)) ` ` `  ` `  `# Driver code ` `num ``=` `[ ``13``, ``14``, ``15``, ``16``, ``17` `] ` `freq ``=` `[ ``2``, ``5``, ``13``, ``7``, ``3` `] ` `n ``=` `len``(num) ` `print` `(harmonicMean(num, freq, n)) ` ` `  ` `  `# This code is contributed by Nikita Tiwari. `

## C#

 `// C# program to find harmonic mean. ` `using` `System; ` ` `  `class` `GFG { ` ` `  `    ``// Function that returns harmonic mean. ` `    ``static` `float` `harmonicMean(``int``[] arr, ``int``[] freq, ` `                                              ``int` `n) ` `    ``{ ` `        ``float` `sum = 0, frequency_sum = 0; ` `        ``for` `(``int` `i = 0; i < n; i++) { ` `            ``sum = sum + (``float``)freq[i] / arr[i]; ` `            ``frequency_sum = frequency_sum + freq[i]; ` `        ``} ` `        ``return` `(frequency_sum / sum); ` `    ``} ` ` `  `    ``// Driver code ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``int``[] num = { 13, 14, 15, 16, 17 }; ` `        ``int``[] freq = { 2, 5, 13, 7, 3 }; ` `        ``int` `n = num.Length; ` `        ``Console.WriteLine(harmonicMean(num, freq, n)); ` `    ``} ` `} ` ` `  `/*This code is contributed by vt_m.*/`

## PHP

 ` `

## Javascript

 ``

Output:

`15.0631`

Time Complexity: O(n)

Auxiliary Space: O(1)
Harmonic mean of numbers using harmonic_mean() in Python:
Simple Python program to find harmonic mean using harmonic_mean() function.

## Python3

 `#'harmonic_mean()' new function added in 'Python3.6' onwards. ` `#Program calculates Harmonic Mean using harmonic_mean() ` ` `  `#imports Python statistics library ` `import` `statistics ` `def` `harmonic_mean(): ` `    ``list``=` `[``13.5``, ``14.5``, ``14.8``, ``15.2``, ``16.1``] ` `    ``print``(statistics.harmonic_mean(``list``)) ` ` `  `#Driver code ` `harmonic_mean() ` ` `  ` `  `#This code is contributed by 'Abhishek Agrawal'. `

`Output: 14.770680729373778`

Time Complexity: O(n)

Auxiliary Space: O(1)

This article is contributed by Dharmendra Kumar. If you like GeeksforGeeks and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

My Personal Notes arrow_drop_up
Related Articles