[Rd] code for sum function

[Rampal Etienne]

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