From: Brahm, David <David.Brahm_at_geodecapital.com>

Date: Sat 19 Aug 2006 - 06:04:53 EST

R-help@stat.math.ethz.ch 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. Received on Sat Aug 19 06:22:31 2006

Date: Sat 19 Aug 2006 - 06:04:53 EST

I was concerned by this result (new in R-2.3.1):
R> x <- c(721.077, 592.291, 372.208, 381.182)
R> sum(x) - 2066.758

[1] 4.547474e-13

But after Roger Peng's <rdpeng@gmail.com> insightful comment that the relative difference (sum(x)/2066.758 - 1) is exactly what is expected, I'm convinced that sum() is indeed really being "more accurate" than it was in 2.2.1, i.e. accurately preserving the numerical imprecision of the original inputs. Sorry for the distraction...

- David Brahm (brahm@alum.mit.edu)

R-help@stat.math.ethz.ch 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. Received on Sat Aug 19 06:22:31 2006

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