[R] rounding in calculation

From: John Lande <john.lande77_at_gmail.com>
Date: Fri, 21 Mar 2008 16:17:28 +0100


dear all,

I report a problem very simple, that I does non know how to handle.

look at the following code:

> a = rep(16.256, 5)
> sum(a[1:5]^2) - (sum(a[1:5])^2/5)

[1] 2.273737e-13

as you can see i retrieve a non 0 value, when i am expected to. what can I do?

> sessionInfo()

R version 2.6.2 (2008-02-08)
i386-pc-mingw32

locale:
LC_COLLATE=Italian_Italy.1252;LC_CTYPE=Italian_Italy.1252;LC_MONETARY=Italian_Italy.1252;LC_NUMERIC=C;LC_TIME=Italian_Italy.1252

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

loaded via a namespace (and not attached): [1] rcompgen_0.1-17

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