Dear All, I am running a r code on 32bit win, involving absolutely small numbers. Although I tried sth like the ratio of numers like 10^(-100) and did not have issue to get the correct answer, but still a little concerned about it. Could anyone give some suggestion or have any experience? Best wishes, Jie [[alternative HTML version deleted]]
On Tue, Jul 31, 2012 at 2:45 PM, Jie <jimmycloud at gmail.com> wrote:> Dear All, > > I am running a r code on 32bit win, involving absolutely small numbers. > Although I tried sth like the ratio of numers like 10^(-100) and did not > have issue to get the correct answer, > but still a little concerned about it. > Could anyone give some suggestion or have any experience?This would be a canonical reference: http://www.validlab.com/goldberg/paper.pdf. Hope this helps, M> > Best wishes, > Jie > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.
On Tue, Jul 31, 2012 at 03:45:14PM -0400, Jie wrote:> Dear All, > > I am running a r code on 32bit win, involving absolutely small numbers. > Although I tried sth like the ratio of numers like 10^(-100) and did not > have issue to get the correct answer, > but still a little concerned about it. > Could anyone give some suggestion or have any experience?Hi. Numbers of the order 10^(-100) are still relatively far from the lower limit and are represented with full precision, which is 53 bits. The smallest number representable in full precision is 2^-1022 = 2.225074e-308 and the smallest representable number (in limited precision) is 2^-1074 4.940656e-324. See http://en.wikipedia.org/wiki/Double_precision_floating-point_format for more detail. Hope this helps. Petr Savicky.