Re: [R] Problem about zero

From: Jorge Ivan Velez <jorgeivanvelez_at_gmail.com>
Date: Tue, 15 Jun 2010 18:03:20 -0400

Hi Yen,

See
http://cran.r-project.org/doc/FAQ/R-FAQ.html#Why-doesn_0027t-R-think-these-numbers-are-equal_003f

HTH,
Jorge

On Tue, Jun 15, 2010 at 6:00 PM, Yen Lee <> wrote:

> Hello, everyone,
>
> There's a problem about zero in R and I really need your help.
>
>
>
> I have a vector shown as x=c(0.1819711,0.4811463,0.1935151,0.1433675),
>
> The sum of this vector is shown as 1 in R, but when I type 1-sum(x), the
> value is not zero, but -2.220446e-16.
>
> I can accept that this value is quite small and could be seen as zero, but
> there would be a problem when it's not really zero but a negative value in
> my algorithm.
>
>
>
> Therefore I would like to know that how could it be avoid.
>
> One way I think is to define the value 1-sum(x) as zero when it is smaller
> than a particular value, but the particular value is not be set yet.
>
> I would like to know more about the definition of the shown zero in R.
>
>
>
> Thank you so much.
>
>
>
> Yen
>
>
> [[alternative HTML version deleted]]
>
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>

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