That's really interesting Rick. I am finding it hard to understand the flatness of the red line. Intuitively the time the subscription process x[idx] takes must increase linearly with the length of the vector idx. So for the line to be flat, it must be the case that the syntax loc(x>x0) is taking less time to run when it returns longer and longer idx vectors (above 0.5 on the chart). Does that make sense from your understanding of the algorithm behind the LOC function?