In this case, that is too little too late. See the other messages in this thread.
On February 17, 2022 4:04:53 PM PST, Andrew Simmons <akwsi...@gmail.com> wrote: >It should also be noted that format(x, digits = 17) instead of >as.character(x) won't lose any accuracy. > >On Thu, Feb 17, 2022, 17:41 Marius Hofert <marius.hof...@uwaterloo.ca> >wrote: > >> Dear expeRts, >> >> I'm familiar with IEEE 754. Is there an easy way to explain why even >> just printing of small numbers fails? >> >> 1e-317 # 1e-317 => fine >> 1e-318 # 9.999987e-319 => gets tricky; seems to call print() => >> as.character() => format() => paste() >> 1e-318 == 9.999987e-319 # TRUE >> 2.48e-324 # prints 4.940656e-324 for me >> 2.48e-324 == 4.940656e-324 # TRUE >> ## Relative error as a plot >> rel_error <- function(x) >> plot(abs((as.numeric(as.character(x)) - x) / x), type = "l", >> ylab = "Relative error between x and as.numeric(as.character(x))") >> rel_error(seq(0.001, 0.001 + .Machine$double.xmin, length.out = 1001)) # >> fine >> rel_error(seq(0, .Machine$double.xmin, length.out = 1001)) # printing >> breaks down >> >> Of course, [0,.Machine$double.xmin] is somewhat of a strange set of >> numbers to consider, >> and I expect things like "==" to be easily fooled there, but already the >> print method (?) >> >> Thanks & cheers, >> Marius >> >> sessionInfo() >> R version 4.1.2 (2021-11-01) >> Platform: x86_64-apple-darwin21.2.0 (64-bit) >> Running under: macOS Monterey 12.1 >> ... >> >> >> ______________________________________________ >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >> 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. >> > > [[alternative HTML version deleted]] > >______________________________________________ >R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see >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. -- Sent from my phone. Please excuse my brevity. ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.