On Mon, 5 Jul 2004, Laura Holt wrote: > What precision is R, please? 64 bit?
Your question lacks precision :) R uses the underlying double precision floating-point arithmetic of the OS it is running on. On all currrent platforms that we know of, that is IEC60566 arithmetic, with an (implicit) 53-bit mantissa. So floating-point operations have double precision, usually with around 53 bits of accuracy. > Where would I find that out typically, please? Type ?.Machine, then print(.Machine). One complication on machines with extended-precision registers (and since that includes the ix86 family, that is most of them) is that some calculations are done with a 64-bit mantissa and finally stored with a 53-bit mantissa. Those may turn out to be more accurate than your expect (which makes measuring accuracy difficult). -- 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 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
