how to calculate the standard deviation of a matrix in matlab

To calculate the standard deviation of a matrix in MATLAB, you can use the std() function. By default, this function operates column-wise, so to find the standard deviation for the entire matrix, you can pass the matrix to std() as a vector (using the (:) notation to flatten the matrix).

main.m
A = [1 2 3; 4 5 6; 7 8 9];
std_dev = std(A(:));
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Alternatively, you can specify the dim parameter to operate along a different dimension. For example, to find the standard deviation of each row, you would use dim=2:

main.m
A = [1 2 3; 4 5 6; 7 8 9];
std_devs = std(A,0,2);
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Note that the 0 parameter indicates that the calculation should use the default normalization (dividing by N rather than N-1).