hello, I have to calculate the determinants of near singular matrices. Presently R just stop at the precision of 2.16 e-16. Can some one tell me how can I set the precision of zero in R ? thanks chen pu
On 2/3/07, pu chen <pchen at uni-bielefeld.de> wrote:> hello,> I have to calculate the determinants of near singular matrices. Presently R just stop at the precision of 2.16 e-16.I'm not sure what you mean by that. Can you explain how you determined that number, perhaps including some code? It happens that on many systems that number is close to the relative machine precision. For example, on my version of R> .Machine$double.eps[1] 2.220446e-16> Can some one tell me how can I set the precision of zero in R ?If you mean how could you change R so that it would give infinitely precise floating point representations for which the relative machine precision is zero I think the only answer is "by magic". In the real world we need to work with the floating point representations on the computers that we have access to. Perhaps you could rethink the calculation you are attempting to perform.
The Ryacas package can do exact arithmetic: http://code.google.com/p/ryacas/ See the vignette for examples. On 2/3/07, pu chen <pchen at uni-bielefeld.de> wrote:> hello, > > I have to calculate the determinants of near singular matrices. Presently R just stop at the precision of 2.16 e-16. > > Can some one tell me how can I set the precision of zero in R ? > > > thanks > > > chen pu > > ______________________________________________ > R-help at 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. >
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