You need the Rmpfr package. Your calculation of 2^64 is an ordinary double precision number with 53 bits of precision.
> library(Rmpfr) Loading required package: gmp Attaching package: ‘gmp’ The following objects are masked from ‘package:base’: %*%, apply, crossprod, matrix, tcrossprod C code of R package 'Rmpfr': GMP using 64 bits per limb Attaching package: ‘Rmpfr’ The following object is masked from ‘package:gmp’: outer The following objects are masked from ‘package:stats’: dbinom, dgamma, dnorm, dpois, pnorm The following objects are masked from ‘package:base’: cbind, pmax, pmin, rbind > class(2) [1] "numeric" > class(2^32) [1] "numeric" > class(2^64) [1] "numeric" > Two <- mpfr(2, precBits=64) > Two^64 1 'mpfr' number of precision 64 bits [1] 18446744073709551616 > class(Two^64) [1] "mpfr" attr(,"package") [1] "Rmpfr" > Two^64 - 1 1 'mpfr' number of precision 64 bits [1] 18446744073709551615 > getPrec(Two) [1] 64 > getPrec(2.) [1] 53 > On Fri, Nov 13, 2020 at 8:45 PM Yousri Fanous <yousri.fan...@gmail.com> wrote: > > I want to calculate 2^64-1 which is > 18446744073709551615 > > I set the following options to prevent scientific notation > options("scipen"=100, "digits"=4) > > x<-2^64 -1 > > x > [1] 18446744073709551616 > > This is not correct. There seem to be still some approximation happening. > How can I get the correct result? > > Yousri > IBM Canada ltd > Software developer > > [[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. ______________________________________________ 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.