[R] Installing R on RedHat7.0

[Prof Brian D Ripley]

On Fri, 3 Nov 2000, Tom Wainwright wrote:

> Thanks!  Building from source worked, and the demos all run.  Several
> others report that R runs smoothly on RedHat7.
> 
> However, not all the tests in $R_HOME/tests succeed.  When I do "make
> test-Examples" in that directory,  it fails executing "base-Ex.R" in the
> "eigen" section, with the error:
> 
> 	Error: abs(sm %*% V - V %*% diag(lam)) < 60 * Meps is not TRUE
> 
> This appears to be a numerical precision problem.  Checking, Meps (i.e.
> .Machine.double.eps) is 1.084202e-19.  Is this a reasonable value for a
> Pentium III?

No. .Machine$double.eps should be about 2e-16.  An i686 does not have
19 digits of precision.  Here's what gcc-2.95.2 gives on a PIII under
RH6.2:

> .Machine
$double.eps
[1] 2.220446e-16

$double.neg.eps
[1] 1.110223e-16

$double.xmin
[1] 2.225074e-308

$double.xmax
[1] 1.797693e+308

$double.base
[1] 2

$double.digits
[1] 53

$double.rounding
[1] 5

$double.guard
[1] 0

$double.ulp.digits
[1] -52

$double.neg.ulp.digits
[1] -53

$double.exponent
[1] 11

$double.min.exp
[1] -1022

$double.max.exp
[1] 1024

$integer.max
[1] 2147483647


> If I rerun test-Examples, all the remaining tests complete with no problem.
> 
> Similarly, make test-Specific fails during arith-true.R, with many tests
> returning FALSE.
> 
> Have others who run R on RedHat7 run these tests? It seems that either
> there's a serious compiler problem, or the .Machine variables are getting
> set wrong, or I have a hardware problem.

The likely story is that that beta compiler is even farther from
IEEE-compliant than is usual for gcc on Linux.  Some of us are
too nervous about it to even try an installation.


-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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