| sd {stats} | R Documentation | 
This function computes the standard deviation of the values in
x.
If na.rm is TRUE then missing values are removed before
computation proceeds.
If x is a matrix or a data frame, a vector of the standard
deviation of the columns is returned.
sd(x, na.rm = FALSE)
x | 
a numeric vector, matrix or data frame. | 
na.rm | 
logical. Should missing values be removed? | 
var for its square, and mad, the most
robust alternative.
sd(1:2) ^ 2