Hello,
Under R 4.5.0 on Windows (x86-64), I get:
> sqrt(.Machine$double.xmax)^2
[1] Inf
> sqrt(.Machine$double.xmax)*sqrt(.Machine$double.xmax)
[1] Inf
On other hand on other platforms, including Debian Linux (x86-64), I
get:
d> sqrt(.Machine$double.xmax)^2
[1] 1.797693134862315508561e+308
d> sqrt(.Machine$double.xmax)*sqrt(.Machine$double.xmax)
[1] 1.797693134862315508561e+308
Windows is running inside a VirtualBox instance on the same host as
Linux. I don't have direct results from the MacOS platforms, but based
on the symptoms that had led me to investigate, the behaviour is as the
Linux.
Adding to the mystery, if I implement the same operation in C, e.g.,
library(inline)
sqrsqrt <- cfunction(sig = c(x = "numeric"), language = "C", "
double sqrtx = sqrt(Rf_asReal(x));
return Rf_ScalarReal(sqrtx*sqrtx);
")
R on Linux yields:
d> sqrsqrt(.Machine$double.xmax)
[1] 1.797693134862315508561e+308
i.e., the same number, whereas R on Windows yields:
d> sqrsqrt(.Machine$double.xmax)
[1] 1.797693134862315508804e+308
which is not Inf but not the same as Linux either.
Lastly, on both platforms,
d> sqrsqrt(.Machine$double.xmax) < .Machine$double.xmax
[1] TRUE
I am not sure if this is a bug, intended behaviour, or something else.
Best Regards,
Pavel
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
