The reason I wrote this script was to get quick results from the command line.
For instance: I could use grep, cut and other unix tools to get the numbers from a file and make quick calculations.
Of course, for complex processing I would use octave or R.
function mean() {
octave -q --eval "mean = mean(load('$1'))"
}
I am sure your approach is much quicker, octave takes a good 0.5s(!) to load on my machine.
Regarding speed, for simple calculations like sum, mean and variance, the bottleneck is in I/O.