Khue,
> On 19/07/2024, at 11:32 AM, Khue Tran <tr...@kenyon.edu> wrote: > > Thank you for the suggestion, Denes, Vladimir, and Dirk. I have indeed > looked into Rmpfr and while the package can interface GNU MPFR with R > smoothly, as of right now, it doesn't have all the functions I need (ie. > eigen for mpfr class) and when one input decimals, say 0.1 to mpfr(), the > precision is still limited by R's default double precision. > Don't use doubles, use decimal fractions: > Rmpfr::mpfr(gmp::as.bigq(1,10), 512) 1 'mpfr' number of precision 512 bits [1] 0.100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002 As for eigen() - I'm not aware of an arbitrary precision solver, so I think the inputs are your least problem - most tools out there use LAPACK which doesn't support arbitrary precision so your input precision is likely irrelevant in this case. Cheers, Simon > Thank you for the note, Dirk. I will keep in mind to send any future > questions regarding Rcpp to the Rcpp-devel mailing list. I understand that > the type used in the Boost library for precision is not one of the types > supported by SEXP, so it will be more complicated to map between the cpp > codes and R. Given Rmpfr doesn't provide all necessary mpfr calculations > (and embarking on interfacing Eigen with Rmpfr is not a small task), does > taking input as strings seem like the best option for me to get precise > inputs? > > Sincerely, > Khue > > On Fri, Jul 19, 2024 at 8:29 AM Dirk Eddelbuettel <e...@debian.org> wrote: > >> >> Hi Khue, >> >> On 19 July 2024 at 06:29, Khue Tran wrote: >> | I am currently trying to get precise inputs by taking strings instead of >> | numbers then writing a function to decompose the string into a rational >> | with the denominator in the form of 10^(-n) where n is the number of >> | decimal places. I am not sure if this is the only way or if there is a >> | better method out there that I do not know of, so if you can think of a >> | general way to get precise inputs from users, it will be greatly >> | appreciated! >> >> That is one possible way. The constraint really is that the .Call() >> interface >> we use for all [1] extensions to R only knowns SEXP types which map to a >> small set of known types: double, int, string, bool, ... The type used by >> the Boost library you are using is not among them, so you have to add code >> to >> map back and forth. Rcpp makes that easier; it is still far from automatic. >> >> R has packages such as Rmpfr interfacing GNU MPFR based on GMP. Maybe that >> is >> good enough? Also note that Rcpp has a dedicated (low volume and friendly) >> mailing list where questions such as this one may be better suited. >> >> Cheers, Dirk >> >> [1] A slight generalisation. There are others but they are less common / >> not >> recommended. >> >> -- >> dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org >> > > [[alternative HTML version deleted]] > > ______________________________________________ > R-package-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-package-devel > ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel
