[R] Looking for greater floating-point precision

Paul Smith phhs80 at gmail.com
Fri Nov 17 13:12:52 CET 2006

On 11/16/06, Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:
> > For my calculations, I am needing to use more floating-point precision
> > than the default one of R. Is that possible? And, if yes, how?
> See package gmp (but that will be slow and cumbersome for all but simple
> calculations).
> The real issue is that R already uses the maximum precision of the FPU for
> many common FPUs (but not all).  Since you have forgotten to tell us
> anything about your environment we don't know if that applies: there may
> be compiler options you can use to raise the precision.
> Please do study the posting guide: we are surprisingly good at
> mind-reading, but prefer to be told exactly what you want to do with R in
> what environment and why you are 'needing' something.

Thanks, Gabor and Prof. Ripley. After some research, I conclude that
the problem occurring to me cannot be removed for any finite
floating-point precision. (I do need infinite floating-point
precision.) The problematic operation is the successive multiplication
of reals between 0 and 1; after a certain number of multiplications,
significant rounding errors occur.

I did read the posting guide, but I could not anticipate the relevance
of indicating the environment that I am using: Fedora Core 6 (Linux)
running on a Pentium Dual Core and R 2.4.0.


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