numerical issue in contour.default?
On 13.09.2013 16:44, Prof Brian Ripley wrote:
On 13/09/2013 15:14, Duncan Murdoch wrote:
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.
You are right, I can reproduce it only on 64 bit.
And not even then: we would not have time to do sufficiently extensive checking.
Agreed, so I'll put a workaround in my package for now.
Reporting to bugs.r-project.org with a patch would get the process rolling.
O.K., I will report it. After a look in the sources I would guess that
it may be in:
src/main/contour-common.h
static int ctr_intersect(double z0, double z1, double zc, double *f)
{
if ((z0 - zc) * (z1 - zc) < 0.0) {
*f = (zc - z0) / (z1 - z0);
return 1;
}
return 0;
}
... but you are right, too many things depend on it.
Many thanks for the immediate feedback!
Thomas