On 8 July 2013 at 06:51, Peng Yu wrote: | > vx=rep(.1, 10) | > options(digits=22) | > fun(vx) | [1] 0.9999999999999998889777
You are printing a data type that has around 16 decimals precision with 22. That is bound to show random stuff at the end. Otherwise, Bill is quite right that one can (and R Core does) use 'long double' in the internal parts of loops which could otherwise accumulate numerical error. There are many texts on numerical computing which cover this. A short and classic paper by David Goldbergs is available in many places under 'what ever computer scientist should know about floating-point arithmetic'. Dirk -- Dirk Eddelbuettel | [email protected] | http://dirk.eddelbuettel.com _______________________________________________ Rcpp-devel mailing list [email protected] https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
