On 21 Nov 2007, at 08:30, Prof Brian Ripley wrote: > On Tue, 20 Nov 2007, Tim Hesterberg wrote: > >> I wrote the original rowSums (in S-PLUS). >> There, rowSums() does not coerce integer to double. > > Actaully, neither does R. It computes a double answer but does no > coercion per se. > >> However, one advantage of coercion is to avoid integer overflow. > > Indeed, as I told Robin Hankin privately, that was the design reason. >
Brian Ripley also reminded me that the sum() of integers is an integer, behaviour that I find desirable. The reason for my starting this thread is that sometimes I actually *want* sums of integers to overflow: my interest is in exact computations where I must be absolutely certain that there can be no rounding error. If the sum cannot be represented in integers, I want this fact to be flagged with extreme vigour as it signals what might be catastrophic loss of precision. At least, that's my current thinking. best wishes rksh >> >> Tim Hesterberg >> >>> ... So, why does rowSums() coerce to double (behaviour >>> that is undesirable for me)? >> >> ______________________________________________ >> R-help@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting- >> guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > -- > Brian D. Ripley, [EMAIL PROTECTED] > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 -- Robin Hankin Uncertainty Analyst National Oceanography Centre, Southampton European Way, Southampton SO14 3ZH, UK tel 023-8059-7743 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
