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Mean Function in MATLAB

  • Last Updated : 29 Jun, 2021

Mean or average is the average of a sequence of numbers. In MATLAB, mean (A) returns the mean of the components of A along the first array dimension whose size doesn’t equal to 1. Suppose that A is a vector, then mean(A) returns the mean of the components. Now, if A is a Matrix form, then mean(A) returns a row vector containing the mean of every column.

Mean{\displaystyle {\bar {x}}={\frac {1}{n}}\left(\sum _{i=1}^{n}{x_{i}}\right)={\frac {x_{1}+x_{2}+\cdots +x_{n}}{n}}}        

Example:

Mean of sequence x = [1,2,3,4,5]  = Sum of numbers/Count of numbers

                                                  = 15/5

                                                  = 3



Different syntax of the mean() method is:

  • M = mean(A)
  • M = mean(A,’all’)
  • M = mean(A,dim)
  • M = mean(A,vecdim)

 M = mean(A)

  • It returns the mean of sequence A.
  • If A is a vector, then it returns the mean of all elements in the vector
  • If A is a matrix, then it returns a vector where each element is the mean of each column in A.

Example:

Matlab




% Input vector
A = [1 2 3 4 5];
disp("Vector :");
disp(A);
 
% Find mean of vector
x = mean(A);
disp("Mean :");
disp(x);

 

 

Output:

 



 

Example:

 

Matlab




% Input matrix
A = [1 1 2; 2 3 2; 0 1 2; 1 5 7];
disp("Matrix :");
disp(A);
 
% Find mean of matrix
x = mean(A);
disp("Mean :");
disp(x);

Output :

M = mean(A, ‘all’)

It returns the mean of all the elements in A either it can be vector or matrix.

Example:

Matlab




% Input matrix
A = [1 1 2; 2 3 2; 0 1 2; 1 5 7];
disp("Matrix :");
disp(A);
 
% Find mean of whole matrix
x = mean(A,'all');
disp("Mean :");
disp(x);

Output :



M = mean(A,dim)

  • It returns the mean of matrix A along each of the given dim.
  • If dim = 1, then it returns a vector where the mean of each column is included.
  • If dim = 2, then it returns a vector where the mean of each row is included.

Example:

Matlab




% Input matrix
A = [1 1 2; 2 3 2; 0 1 2; 1 5 7];
disp("Matrix :");
disp(A);
 
% Find mean of each row in matrix
x = mean(A,2);
disp("Mean :");
disp(x);

Output :

M = mean(A,vecdim)

  • It returns the mean of A based on the specified dimensions vecdim in A.
  • If A is a 2-by-2-by-3 array, then mean(A,[1 2]) calculates the mean of each page of size 2-by-2 as it’s considered as a single entity. So it returns the vector of size 3 as the mean of each page.

Example:

Matlab




% Creating a 2-by-3-by-3 array
A(:,:,1) = [12 2; -1 1];
A(:,:,2) = [3 13; -2 10];
A(:,:,3) = [4 7 ; 3 -3];
disp("Array :");
disp(A);
 
% Calculate mean of each page
M1 = mean(A,[1 2]);
disp("Mean of each page :");
disp(M1);

Output:




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