[Rd] R-intro: function 'stderr' and 'sd'

[Martin Maechler]

>>>>> William Dunlap <wdunlap at tibco.com>
>>>>>     on Tue, 13 Sep 2016 09:06:00 -0700 writes:

    > While you are editing that, you might change its name from 'stderr'
    > to standardError (or standard_error, etc.) so as not to conflict with
    > base::stderr().

oh yes.. blush! ..
Martin

    > Bill Dunlap
    > TIBCO Software
    > wdunlap tibco.com

    > On Tue, Sep 13, 2016 at 8:55 AM, Martin Maechler <maechler at stat.math.ethz.ch
    >> wrote:

    >> >>>>> Suharto Anggono Suharto Anggono via R-devel <r-devel at r-project.org>
    >> >>>>>     on Fri, 9 Sep 2016 16:52:01 +0000 writes:
    >> 
    >> > In "An Introduction to R" Version 3.3.1, in "4.2 The function
    >> tapply() and ragged arrays", after
    >> > stderr <- function(x) sqrt(var(x)/length(x))  ,
    >> > there is a note in brackets:
    >> > Writing functions will be considered later in [Writing your own
    >> functions], and in this case was unnecessary as R also has a builtin
    >> function sd().
    >> 
    >> > The part "in this case was unnecessary as R also has a builtin
    >> function sd()" is misleading. The builtin function sd() doesn't calculate
    >> standard error of the mean. It calculates standard deviation. The function
    >> 'stderr' can use 'sd':
    >> > function(x) sd(x)/sqrt(length(x))
    >> 
    >> You are right; thank you Suharto.
    >> It now says
    >> 
    >> (Writing functions will be considered later in @ref{Writing your own
    >> functions}.  Note that @R{}'s a builtin function @code{sd()} is something
    >> different.)
    >> 
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    >> 

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