Difference between MATLAB’s numel and length functions

For a 1-by-N array, they are essentially the same. For a multidimensional array M, they can give different results:

• numel(M) is equivalent to prod(size(M)).
• length(M) is equivalent to max(size(M)). If M is empty (i.e. any dimension is 0), then length(M) is 0.