On 23/03/2010 1:28 PM, Bond, Stephen wrote: > Dear R developers, > > Could you, please, point me to the source file containing the implementation of NA values? I have a feeling this isn't what you want, but what you asked for is in https://svn.r-project.org/R/trunk/src/main/arithmetic.c in particular around lines 110 and 160. Duncan Murdoch