sd Standard Deviation
 Description
This function computes the standard deviation of the values in x. If na.rm is TRUE then missing values are removed before computation proceeds. 
Usage
sd(x, na.rm = FALSE)
Arguments
| x | a numeric vector or an R object but not a  | 
| na.rm | logical. Should missing values be removed? | 
Details
Like var this uses denominator n - 1. 
The standard deviation of a length-one or zero-length vector is NA. 
See Also
var for its square, and mad, the most robust alternative. 
Examples
sd(1:2) ^ 2
    Copyright (©) 1999–2012 R Foundation for Statistical Computing.
Licensed under the GNU General Public License.