This function computes the standard deviation of the values in
`x`

.
If `na.rm`

is `TRUE`

then missing values are removed before
computation proceeds.

`sd(x, na.rm = FALSE)`

x

a numeric vector or an R object but not a
`factor`

coercible to numeric by `as.double(x)`

.

na.rm

logical. Should missing values be removed?

Like `var`

this uses denominator \(n - 1\).

The standard deviation of a length-one or zero-length vector is `NA`

.

# NOT RUN { sd(1:2) ^ 2 # }