Full_Name: Cuvelier Etienne
Version: R version 2.2.1
OS: Windows XP
Submission from: (NULL) (81.240.71.204)
If we use the "density" function "far" from the data, some values are
negatives.
I know that these value of the density are "near equal" to zero, but the change
of sign can involve some "false" decision.
Here is an example of this fact:
> x = c(0.006, 0.002, 0.024, 0.02, 0.034, 0.09, 0.074, 0.072, 0.122,
+ 0.048, 0.044, 0.168)
>
> min(x)
[1] 0.002
> max(x)
[1] 0.168
>
> result = density(x,n=20, from = -1 , to = 1)
>
> result$y
[1] 2.433854e-17 1.726562e-17 1.285227e-16 2.359248e-16
[5] 4.628709e-17 -1.535879e-16 1.438105e-16 2.023210e-16
[9] 2.649354e-11 1.438340e-01 7.679909e+00 1.767860e+00
[13] 2.056151e-04 -1.407219e-16 -3.575895e-18 -1.979607e-16
[17] -1.574544e-17 -2.257917e-17 -2.305234e-16 4.052727e-18
>
> #A plot of the "fluctuations" near zero
> plot(result$x,result$y,type="l",xlim=c(-1,1),ylim=c(-10^-14,10^-14))
> abline(h=0)
>
> #All neagtives value of density are "near equal" to zero
> all(apply(as.matrix(result$y[result$y<0]),1,all.equal, target=0)==TRUE)
[1] TRUE
> sessionInfo()
R version 2.2.1, 2005-12-20, i386-pc-mingw32
attached base packages:
[1] "methods" "stats" "graphics" "grDevices" "utils"
[6] "datasets" "base"
> Sys.info()
sysname release
"Windows" "NT 5.1"
version nodename
"(build 2600) Service Pack 2" "WINXP"
machine login
"x86" "Etienne"
user
"Etienne"
> R.Version()
$platform
[1] "i386-pc-mingw32"
$arch
[1] "i386"
$os
[1] "mingw32"
$system
[1] "i386, mingw32"
$status
[1] ""
$major
[1] "2"
$minor
[1] "2.1"
$year
[1] "2005"
$month
[1] "12"
$day
[1] "20"
$"svn rev"
[1] "36812"
$language
[1] "R"
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