z-Scores(standard deviation and mean) in PHP

Question

I am trying to calculate Z-scores using PHP. Essentially, I am looking for the most efficient way to calculate the mean and standard deviation of a data set (PHP array). Any

Answer 1

How about using the built in statistics package like stats_standard_deviation and stats_harmonic_mean. I can't find a function for standard means, but if you know anything about statistics, I'm sure you can figure something out using the built-in functions.