In this case, thread-based workers already avoid copying the large array m to the workers. See this section in the doc. Note that when you call sin(m) that will create a new temporary array of the same size as m for the output.
Perhaps somewhat counter-intuitively for MATLAB, you might be better off using a for loop (rather than vectorised operations as you have in your example code) to operate on the large array m to avoid making same-sized temporary arrays during the computation.
