It's a difference in the `libc'. Asking for more precision than the arithmetic has is asking for fairly random results. The differences are as likely to be in the *printing* as in the computations.
On Fri, 31 Jan 2003, Bob Gray wrote: > Does anyone know precisely what is different about the arithmetic > and/or storage of double precision floating point to produce the > following differences between the Sun and Windows versions (Splus 6 > on the same Windows 2000 machine gives the same results as Solaris)? > > R 1.6.1, Sun Solaris, gcc + an old Sun f77 > > options(digits=20) > > 1+(1/2^53+1/2^106) > [1] 1 > > 1+(1/2^53+1/2^105) > [1] 1.0000000000000002 > > 1+(1/2^53+1/2^64) > [1] 1.0000000000000002 > > 1+(1/2^53+1/2^63) > [1] 1.0000000000000002 > > R 1.6.1, Windows 2000, binary downloaded from CRAN > > options(digits=20) > > 1+(1/2^53+1/2^106) > [1] 1 > > 1+(1/2^53+1/2^105) > [1] 1 > > 1+(1/2^53+1/2^64) > [1] 1 > > 1+(1/2^53+1/2^63) > [1] 1.0000000000000002 > > (This may be frivolous, but I have been using the first 2 lines as an > example in a course.) > > Thanks > -- > Bob Gray > > ______________________________________________ > [EMAIL PROTECTED] mailing list > http://www.stat.math.ethz.ch/mailman/listinfo/r-help > -- 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 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
