From Martyn.Byng at nag.co.uk  Mon Nov 21 15:41:36 2011
From: Martyn.Byng at nag.co.uk (Martyn Byng)
Date: Mon, 21 Nov 2011 14:41:36 -0000
Subject: [Rd] a^b when a is large and b < 1 (64bit R on windows 7)
Message-ID: <49E76DF37649DC48A4CE882BC8CE51C901F44592@nagmail2.nag.co.uk>

Hi,

I'm getting some strange behaviour when trying to use the power operator
(a^b) when a is large and b is less than one:

big <- .Machine$double.xmax
big
big^0.5
sqrt(big)

> big <- 1.797693134862315708384e+308
> big^0.5
[1] Inf
> sqrt(big)
[1] 1.340781e+154


I'm guessing that this behaviour is not expected, or am I missing
something about ^?

Cheers

Martyn



> sessionInfo()
R version 2.14.0 (2011-10-31)
Platform: x86_64-pc-mingw32/x64 (64-bit)

locale:
[1] LC_COLLATE=English_United Kingdom.1252
[2] LC_CTYPE=English_United Kingdom.1252
[3] LC_MONETARY=English_United Kingdom.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United Kingdom.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

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[Rd] a^b when a is large and b < 1 (64bit R on windows 7)
Martyn Byng