in reply to to calculate mean and variance

Or if you do not want to reinvent a wheel: Statistics::Lite, Statistics::Basic or Statistics::Descriptive.

CountZero

A program should be light and agile, its subroutines connected like a string of pearls. The spirit and intent of the program should be retained throughout. There should be neither too little or too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity." - The Tao of Programming, 4.1 - Geoffrey James

In Section Seekers of Perl Wisdom