[R] R-0.64.0 installation on SGI IRIX 6.5 machine

[Peter Dalgaard BSA]

Jayshree Sarma <jsarma at cs.gmu.edu> writes:


>   Given below is the output from R.  I do not get 560 but a rather large
> number.  I ran the individual pieces too so you can compare the output
> with the output from your machine and maybe tell me which is one that is
> wrong. Is the code within abs()  correct?
> 
> ***************output from R*************
> Type    "q()" to quit R.
> 
> > log10(2)
> [1] 0.30103
> > -.Machine$double.max.exp
> [1] -1024
> > 10^(-.Machine$double.max.exp*log10(2))
> [1] 0

This is where the trouble starts. Other systems get a small number:
PD> 10^(-.Machine$double.max.exp*log10(2))
[1] 5.562685e-309

This underflow is probably no big deal, just an indication that your
system might not do perfect IEEE-standard arithmetic. Martin Maechler
may have more information on this.

> > .Machine$double.xmax
> [1] 1.797693e+308
> > .Machine$double.xmax * 10^(-.Machine$double.max.exp*log10(2))
> [1] 0

Normally 1

> > abs(1- .Machine$double.xmax * 10^(-.Machine$double.max.exp*log10(2)))
> [1] 1

Normally  (near-) zero.

> > Meps <- .Machine $ double.eps
> > .Machine $ double.eps
> [1] 2.220446e-16
> > abs(1- .Machine$double.xmax * 10^(-.Machine$double.max.exp*log10(2)))/Meps 
> [1] 4.5036e+15
> > abs(1- .Machine$double.xmax * 10^(-.Machine$double.max.exp*log10(2)))/Meps < 1e3
> [1] FALSE



-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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