[Rd] bug (PR#13570)

[Berwin A Turlach]

G'day Peter,

On Thu, 05 Mar 2009 09:09:27 +0100
Peter Dalgaard <p.dalgaard at biostat.ku.dk> wrote:

> rhafen at stat.purdue.edu wrote:
> > <<insert bug report here>>
> > 
> > This is a CRITICAL bug!!!  I have verified it in R 2.8.1 for mac
> > and for windows.  The problem is with loess degree=0 smoothing.
> > For example, try the following:
> > 
> > x <- 1:100
> > y <- rnorm(100)
> > plot(x, y)
> > lines(predict(loess(y ~ x, degree=0, span=0.5)))
> > 
> > This is obviously wrong.
> 
> Obvious? How? I don't see anything particularly odd (on Linux).

Neither did I on linux; but the OP mentioned mac and windows. 

On windows, on running that code, the lines() command added a lot of
vertical lines; most spanning the complete window but some only part.  

Executing the code a second time (or in steps) gave sensible
results.  

My guess would be that some memory is not correctly allocated or
initialised.  Or is it something like an object with storage mode
"integer" being passed to a double?  But then, why doesn't it show on
linux?

Happy bug hunting.  If my guess is correct, then I have no idea how to
track down such things under windows.....

Cheers,

	Berwin