[Rd] Warning: you may need to use R-patched with recent R distros

[Ken.Williams at thomsonreuters.com]

For the complex-numbers bug, do you know a reliable way (besides looking
at version numbers) to determine whether the bug is present or absent in a
given build?  

I don't know what version of gcc was used in my build nor the optimization
flags, so I did a few test exponentiations z^n and the results look okay,
but maybe I'm not tickling the right bits.


--
Ken Williams
Senior Research Scientist
Thomson Reuters
Phone: 651-848-7712
ken.williams at thomsonreuters.com
http://labs.thomsonreuters.com





On 1/31/11 1:48 PM, "Prof Brian Ripley" <ripley at stats.ox.ac.uk> wrote:

>Two things have emerged in testing on x86_64 Fedora 14 which mean that
>a recent R-patched is probably needed.
>
>1) That OS uses zlib 1.2.5: that claims to be binary-compatible with
>zlib 1.2.3 but is not, as we found (painfully) on Windows.  The remedy
>was to remap _all_ the symbols in R's own copy of zlib (not just those
>zlib arranged to remap).
>
>The symptoms were crashes using packages XML and rgoobi (both of which
>link to zlib) and incorrect results in RJaCGH (which contains a copy
>of zlib).  There may well be other problems ....
>
>2)  Fedora 14 uses gcc 4.5.1. With CFLAGS containing the default -O2
>or higher, HAVE_C99_COMPLEX was detected as false because there is a
>(genuine) incompatibility between types Rcomplex and C99's double
>complex.  This means that R's fallback code is used, and regretably
>that contains a serious bug in an 'optimization' by a colleague, so
>z^n is incorrect for most complex z and integer n (and has been since
>2.10.0).  The remedy is to use R-patched or R-devel, or only optimize
>to -O.
>
>We've also seen incorrect results from package mvtnorm when C
>optimization was -O3.
>
>The upshot is that there is likely to be a 2.12.2 to fix these issues.
>
>-- 
>Brian D. Ripley,                  ripley at stats.ox.ac.uk
>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
>
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