On 17 November 2020 at 12:34, Bill Dunlap wrote: | I just got a new Windows laptop (i7, 10th generation CPU), installed | 'Windows Subsystem for Linux 2' and then installed Ubuntu 20.04 and | used 'apt-get install' to install packages that the R build seems | to require. In particular, I am using gcc version 9.3.0. The | build went without a hitch but the tests showed that deparse(1e-16) | produced "1.00000000000000e-16" instead of the expected "1e-16". | | It looks like the problem is in src/main/format.c:scientific(). The | lowest two+ bytes in the fractional part of the long double (80-bit) | return value of powl(10.0L, -30L), seem to be corrupted. I made a | standalong program to test powl and saw no problem - it gives the | same results for the fractional part as bc does. | | bc: A2425FF7 5E14FC31 A125... | standalone: 22425FF7 5E14FC32 | R: 22425FF7 5E151800 | | There are lots of other small numbers with the same problem: | | | > grep(value=TRUE, "0e", | vapply((1+(0:10000)/1000)*1e-15, deparse, "")) | [1] "8.56000000000000e-15" "8.71700000000000e-15" "8.77800000000000e-15" | [4] "8.93500000000000e-15" "9.50800000000000e-15" "9.83800000000000e-15" | [7] "9.89900000000000e-15" "9.93400000000000e-15" "9.99500000000000e-15" | > str(grep(value=TRUE, "0e", vapply((1+(0:10000)/1000)*1e-14, deparse, ""))) | chr [1:295] "8.00200000000000e-14" "8.00500000000000e-14" ... | | Has anyone else seen this? I am wondering if this is an oddity in WSL2 | | or Ubuntu's gcc-9.3.0.
Plain Ubuntu 20.04.1 here, current. No issue: > str(grep(value=TRUE, "0e", vapply((1+(0:10000)/1000)*1e-14, deparse, ""))) chr(0) > I made sure to start R as `R --vanilla` to not have anything in my dotfiles affect printing. Dirk -- https://dirk.eddelbuettel.com | @eddelbuettel | e...@debian.org ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
