> From: setzer.woodrow@epa.gov
> Date: Thu, 27 Jan 2000 16:37:08 +0100 (MET)
> dweibull(0,1,1) evaluates to 0; it should be 1.
Is that not a matter of opinion? Note the help page says
The Weibull distribution with `shape' parameter a and
`scale' parameter b has density given by
f(x) = (a/b) (x/b)^(a-1) exp(- (x/b)^a)
for x > 0.
> Note that dweibull(.Machine$double.eps) evaluates to 1.
>
> > dweibull(.01,1,1)
> [1] 0.9900498
> > dweibull(.00001,1,1)
> [1] 0.99999
> > dweibull(.Machine$double.eps,1,1)
> [1] 1
> > dweibull(0,1,1)
> [1] 0
I would say the Weibull density was defined to be non-zero on (0, Inf),
and S-PLUS agrees with me, as does the help page. I don't see a bug in
the results you present which are consistent with the documentation.
--
Brian D. Ripley, ripley@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272860 (secr)
Oxford OX1 3TG, UK Fax: +44 1865 272595
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