[Rd] numerical issue in contour.default?

[Duncan Murdoch]

On 13/09/2013 10:01 AM, Thomas Petzoldt wrote:
> Dear R developers,
>
> I found a small issue while plotting contours of data containing both
> "usual" and "very small" numbers. It appeared with both R 3.0.1 and
> R-Devel on Windows, and I could reproduce it on Linux. Would it be
> possible to solve this before the upcoming release?

I don't see the error in 32 bits, but I do see it in 64 bits.  I think 
it's really unlikely this will be fixed before 3.0.2, unless you send a 
well tested patch in the next few days.  Code freeze is on Wednesday.

Duncan Murdoch
>
> Thanks a lot for developing this great software!
>
> Thomas
>
>
> Example:
> ########
>
>
> set.seed(357)
> z1 <- matrix(runif(100, -1e-180, 1e-180), nrow = 10)
> contour(z1)    # ok
>
> z2 <- matrix(c(runif(50, -1, 1), runif(50, -1e-180, 1e-180)), nrow = 10)
> contour(z2)   # Error in contour.default(z) : k != 2 or 4
>
> contour(z2 * 1e20)        # 20 worked, 19 produced error
> contour(round(z2, 179))   # rounding to 179 digits works but not 180
>
>
> > sessionInfo()
> R Under development (unstable) (2013-09-11 r63910)
> Platform: x86_64-w64-mingw32/x64 (64-bit)
>
> locale:
> [1] LC_COLLATE=German_Germany.1252  LC_CTYPE=German_Germany.1252
> [3] LC_MONETARY=German_Germany.1252 LC_NUMERIC=C
> [5] LC_TIME=German_Germany.1252
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
>
>
>
>