fastest way to get standard deviation 2d array of a 3d array in matlab

One way to accomplish this task is by using the std function with the [] option to consider all sub-matrices along the third dimension. Here's an example code snippet:

main.m
% Example 3D array
A = randn(4, 5, 3);

% Compute standard deviation along the third dimension
std_array = std(A, [], 3);
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In the example above, A is a 3D matrix with size 4 x 5 x 3. We apply the std function with the [] option to consider all sub-matrices along the third dimension (i.e., the 3 in the function call), which corresponds to the 2D arrays along the third dimension. The resulting std_array is a 2D matrix with size 4 x 5, where each element corresponds to the standard deviation of the corresponding sub-matrix along the third dimension.