[R] Odd underflow(?) error
William Faulk
wfaulk at icoria.com
Fri Dec 3 22:01:34 CET 2004
I'm still trying to install R on my Irix machine. Now I have a new
problem that crops up during the checks. I've found the root cause, and
it's that R is returning zero for certain things for reasons I don't
understand.
2.225073859e-308, entered directly into R, responds "2.225074e-308".
2.225073858e-308 responds "0".
Their negative values respond similarly, so it would appear that
somewhere in there is the smallest absolute value that that installation
of R will hold.
On another machine where the checks passed, both responses are correct,
not just the first one. The underflow there is significantly lower,
with much less accuracy, as opposed to what seems to be good accuracy on
what looks like the broken one. The values there are:
2.4703282293e-324 gives 4.940656e-324
2.4703282292e-324 gives 0
My first thought was that GMP and/or MPFR weren't working properly, so I
recompiled GMP, which passed all of its tests, and GCC, making sure to
imclude support for them. This made no difference.
Anyone have any ideas, including which one is broken? Both?
-Bitt
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