On Jun 28, 2012, at 22:49 ,
wrote:
> Hi,
>
> With R version 2.10.0 (2009-10-26) on Windows, I computed the p=1.e-20
> quantile of the geometric distribution with parameter prob=0.1.
>
>> qgeom(1.e-20,0.1)
> [1] -1
>
> But this is not possible, since X=0,1,2,...
>
> I guess that this might be a bug in the quantile function, which should use
> the log1p function, instead of the naive formula.
>
> Am I correct ?
Nope. (The source is availably, you know).
The problem is that a slight fuzz is subtracted inside ceil(), but there's
no check that the result is positive.
qnbinom(, size=1) is equivalent and does get right, by the way.
-pd
>
> Best regards,
>
> Michaël
>
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--
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Email: pd@cbs.dk Priv: pda...@gmail.com
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