On 11/17/06, Paul Smith <[EMAIL PROTECTED]> wrote: > On 11/16/06, Prof Brian Ripley <[EMAIL PROTECTED]> 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. >
Note that Ryacas can do exact rational arithmetic too in case the reason your reals require infinite precision is just that they are attempting to represent rationals. > yacas("1/2 * 3/4 * 7/8") expression(21/64) ______________________________________________ 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.