mean

Mean or average of elements in an array

Usages

M = mean(A)

• When A is a scalar, M is equal to A.
• When A is a vector, M is equal to the mean of elements of A.
• When A is a matrix or a multidimensional array, an element of M is equal to the mean of elements of the corresponding vector of A along its first non-singleton dimension.
• If A is empty, it returns an empty array.

M = mean(A, k)

• This is the same as the previous cases, except that each element of M corresponds to a vector of A along its k-th dimension.
• If the k-th dimension has zero length, then it returns an empty array.

💡 If a vector contains NaN, the mean of its elements given by mean will be NaN.

Example

• Finding the mean of 1,000 observations of a random variable following the exponential distribution with mean $\mu=30$. The mean obtained by mean is fairly accurate according to the relative error. The error can be further reduced by using more samples, say, 10,000.

Input

% Anonymous function for calculating relative error in percentage
relative_error = @(x) abs(x - 30) / 30 * 100;
% Observations
r = exprnd(30,1,1000);
relative_error(mean(r))
% Smaller error by using more samples
r = exprnd(30,1,10000);
relative_error(mean(r))

Output

ans = 
 2.3736

ans = 1e-1 × 
 6.5230