From g@bembecker @end|ng |rom gm@||@com  Thu Feb 21 20:42:55 2019
From: g@bembecker @end|ng |rom gm@||@com (Gabriel Becker)
Date: Thu, 21 Feb 2019 11:42:55 -0800
Subject: [Rd] code for sum function
In-Reply-To: <CABghstTiOPRfJgFTgw7_V5UbG3wNn36oWHnch7YBfrbLwH_ZXw@mail.gmail.com>
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Hi all,

>From what I can see from my checkout of the Rsources (in src/main/summary.c
as pointed out by others) sums are calculated the "naive" way (see rsum  c
function) but  means are actually calculated something akin to the Neumaier
way (see real_mean c function).

Just an fyi.
~G

On Thu, Feb 21, 2019 at 9:03 AM Ben Bolker <bbolker at gmail.com> wrote:

> Specifically: https://svn.r-project.org/R/trunk/src/main/summary.c
>
> And if you don't want to deal with Subversion, you can look at the
> read-only github mirror:
>
>
> https://github.com/wch/r-source/blob/e5b21d0397c607883ff25cca379687b86933d730/src/main/summary.c#L115-L131
>
> On Thu, Feb 21, 2019 at 11:57 AM David Winsemius <dwinsemius at comcast.net>
> wrote:
> >
> >
> > On 2/20/19 2:55 PM, Rampal Etienne wrote:
> > > Dear Tomas,
> > >
> > > Where do I find these files? Do they contain the code for the sum
> function?
> >
> > Yes.
> >
> > https://svn.r-project.org/R/trunk/
> >
> >
> > David
> >
> > >
> > > What do you mean exactly with your point on long doubles? Where can I
> find
> > > documentation on this?
> > >
> > > Cheers, Rampal
> > >
> > > On Mon, Feb 18, 2019, 15:38 Tomas Kalibera <tomas.kalibera at gmail.com
> wrote:
> > >
> > >> See do_summary() in summary.c, rsum() for doubles. R uses long double
> > >> type as accumulator on systems where available.
> > >>
> > >> Best,
> > >> Tomas
> > >>
> > >> On 2/14/19 2:08 PM, Rampal Etienne wrote:
> > >>> Hello,
> > >>>
> > >>> I am trying to write FORTRAN code to do the same as some R code I
> > >>> have. I get (small) differences when using the sum function in R. I
> > >>> know there are numerical routines to improve precision, but I have
> not
> > >>> been able to figure out what algorithm R is using. Does anyone know
> > >>> this? Or where can I find the code for the sum function?
> > >>>
> > >>> Regards,
> > >>>
> > >>> Rampal Etienne
> > >>>
> > >>> ______________________________________________
> > >>> R-devel at r-project.org mailing list
> > >>> https://stat.ethz.ch/mailman/listinfo/r-devel
> > >>
> > >>
> > >       [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > R-devel at r-project.org mailing list
> > > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
> > ______________________________________________
> > R-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
>
> ______________________________________________
> R-devel at r-project.org mailing list
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>

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[Rd] code for sum function
Gabriel Becker