Yes, all of the numbers are positive. I actually have a Bayesian posterior sample of log likelihoods [i.e. thousands of ln(likelihood) scores]. I want to calculate the harmonic mean of these likelihoods, which means I need to convert them back into likelihoods [i.e. e^ln(likelihood)], calculate the harmonic mean, and then take the log of the mean. I have done this before in Mathematica, but I have a simulation pipeline written almost entirely in R, so it would be nice if I could do these calculations in R.
If R cannot handle such small values, then perhaps there's a way to calculate the harmonic mean from the log likelihood scores without converting back to likelihoods? I am a biologist, not a mathematician, so any recommendations are welcome! Thanks! -Jamie spencerg wrote: > > Are all your numbers positive? If yes, have you considered using > logarithms? > > I would guess it is quite rare for people to compute likelihoods. > Instead I think most people use log(likelihoods). Most of the > probability functions in R have an option of returning the logarithms. > > Hope this helps. > Spencer > > joaks1 wrote: >> I need to perform some calculations with some extremely small numbers >> (i.e. >> likelihood values on the order of 1.0E-16,000). Even when using the >> double() function, R is rounding these values to zero. Is there any way >> to >> get R to deal with such small numbers? >> >> For example, I would like to be able to calculate e^-10000 (i.e. >> exp(-10000)) without the result being rounded to zero. >> >> I know I can do it in Mathematica, but I would prefer to use R if I can. >> Any help would be appreciated! >> >> Many Thanks in Advance! >> > > ______________________________________________ > R-help@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. > > -- View this message in context: http://www.nabble.com/Beyond-double-precision--tp23452471p23457955.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@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.
