Dear Rampal, you can download R source code in form of a tarball or from subversion, please see https://cran.r-project.org/doc/manuals/R-admin.html#Obtaining-R https://cran.r-project.org/doc/manuals/R-admin.html#Using-Subversion-and-rsync
There is also a web access to subversion, so specifically the sum is available in https://svn.r-project.org/R/trunk/src/main/summary.c The definition of LDOUBLE is here https://svn.r-project.org/R/trunk/src/include/Defn.h The index of R manuals is here https://cran.r-project.org/manuals.html The online documentation inside R gives for ?sum " Loss of accuracy can occur when summing values of different signs: this can even occur for sufficiently long integer inputs if the partial sums would cause integer overflow. Where possible extended-precision accumulators are used, typically well supported with C99 and newer, but possibly platform-dependent. " Best, Tomas On 2/20/19 11:55 PM, Rampal Etienne wrote: > Dear Tomas, > > Where do I find these files? Do they contain the code for the sum > function? > > 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.kalib...@gmail.com > <mailto:tomas.kalib...@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@r-project.org <mailto:R-devel@r-project.org> mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel