This help topic is for R version 2.9.0. For the current version of R, try https://stat.ethz.ch/R-manual/R-patched/library/stats/html/sd.html
sd {stats}R Documentation

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. If x is a matrix or a data frame, a vector of the standard deviation of the columns is returned.

Usage

sd(x, na.rm = FALSE)

Arguments

x

a numeric vector, matrix or data frame. An object which is not a vector, matrix or data frame is coerced (if possible) by as.vector.

na.rm

logical. Should missing values be removed?

Details

Like var this uses denominator n - 1.

The standard deviation of a zero-length vector (after removal of NAs if na.rm = TRUE) is not defined and gives an error. The standard deviation of a length-one vector is NA.

See Also

var for its square, and mad, the most robust alternative.

Examples

sd(1:2) ^ 2

[Package stats version 2.9.0 ]