'normalized' is key. A normalized double precision floating point
number has 52 binary digits of precision and .Machine$double.eps/2
does not. E.g.,
bitsOfPrecision - function(x)max(which( x != x*(1+2^-(1:60
bitsOfPrecision(4)
[1] 52
bitsOfPrecision(.Machine$double.xmin)
[1] 52
bitsOfPrecision(.Machine$double.xmin/2)
[1] 51
bitsOfPrecision(.Machine$double.xmin/4)
[1] 50
Google for 'normalized floating point'.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
-Original Message-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf
Of Marius Hofert
Sent: Tuesday, September 10, 2013 2:50 PM
To: R-help
Subject: [R] double.xmin really the smallest non-zero normalized
floating-point number?
Hi,
?.Machine says that 'double.xmin' is 'the smallest non-zero normalized
floating-point number'. On my machine, this is 2.225074e-308. However,
2.225074e-308 / 2 is 0 and smaller than 2.225074e-308, so
double.xmin is not the smallest such number (?) Am I missing anything?
Cheers,
Marius
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