I just found out that I can do: x <- 0/0
in my R without any problem, it is only when I was trying to print the value of x by simply type x and return, R crashed with a sigh of segfault .... This is so wierd. I will try to report it to the Gentoo forum and see if any other gentoo user has the same problem. Xing --- Prof Brian Ripley <[EMAIL PROTECTED]> wrote: > To expand on Dirk's answer, R relies on fairly close compliance to > IEC60559 (aka IEEE754) arithmetic in which 0/0 = NaN. As R is > C/Fortran > program, this is a function of your C/Fortran compilers (it is most > likely > an FPU setting controlled by the compiler than libc). Problems in > this > area are documented in the R-admin manual. > > We don't know the CPU here, so ix86 is a plausible guess. That has > a FPU > control word that determines if 0/0 is NaN or an exception. Prior > to > glibc 2.1 it could be set by __setfpucw and R sets it if > NEED___SETFPUCW > is defined (only in older Linuxen). > > Other people using Gentoo are not reporting problems, so this has > to be a > very specific problem, one which is best addressed to a Gentoo > list. Try > a very simple C program such as > > #include <stdio.h> > int main() > { > double x = 0.0; > printf("x/x = %f\n", x/x); > } > > R is doing nothing different on my Linux box (except it arranges to > print > NaN not nan regardless of platform). > > On Thu, 18 Aug 2005, Dirk Eddelbuettel wrote: > > > > > On 18 August 2005 at 16:01, Xing Qiu wrote: > > | Hi, > > | > > | I noticed that when I was conducting some calculation > involving > > | finding correlation coeficients, R stopped abnormally. So I did > some > > | research, and find out that 0/0 was the culprit. For sure 0/0 > is not > > | a valid expression, but R should give a warning, an error msg > or NaN > > | instead of segmentation fault. > > | > > | I am using R 2.1.0 under Gentoo Linux. My GCC version is > 3.3.5. > > > > [EMAIL PROTECTED]:~> R > > > > R : Copyright 2005, The R Foundation for Statistical Computing > > Version 2.1.1 (2005-06-20), ISBN 3-900051-07-0 > > > > R is free software and comes with ABSOLUTELY NO WARRANTY. > > You are welcome to redistribute it under certain conditions. > > Type 'license()' or 'licence()' for distribution details. > > > > R is a collaborative project with many contributors. > > Type 'contributors()' for more information and > > 'citation()' on how to cite R or R packages in publications. > > > > Type 'demo()' for some demos, 'help()' for on-line help, or > > 'help.start()' for a HTML browser interface to help. > > Type 'q()' to quit R. > > > >> 0/0 > > [1] NaN > >> > > > > No problem on Debian 'testing' with R 2.1.1. You may want to try > a different > > libc. > > > > Dirk > > > > -- > > Statistics: The (futile) attempt to offer certainty about > uncertainty. > > -- Roger Koenker, 'Dictionary of Received Ideas of > Statistics' > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > > > -- > Brian D. Ripley, [EMAIL PROTECTED] > Professor of Applied Statistics, > http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html