>Variance is just square of std. dev, no?
No ! Stdev is divided by count, Variance by (count - 1)
I think the difference really has to do with what you are calculating.
If you want the std. dev./var. of the data THEMSELVES, divide by the
count. If you want an estimate about the properties of the POPULATION
from which the data were sampled, divide by count-1. People have
needs for both in different circumstances.
Perhaps there needs to be two versions, or a function argument, to
distinguish the two uses, both of which are legitimate.
Cheers,
Brook