On Fri, 19 Mar 2004, Stegemann, Berthold wrote: > In an experimental setup we obtain z-data samples at equidistant grid points. > > The surf.gls (Kriging) algorithm produces an error under this > circumstance when performing the Choleski decomposition. > > A workaround is to dither the grid coordinates using (x <- rnorm(length(x)) ; y<- rnowm(length(y))).
That's not dithering but changing them completely. Hint: ?jitter. > Question: Is this an expected behaviour of the surf.gls function ? No, and it has been tested under those circumstances. Did you adjust the accuracy of the approximation via nx? Is your covariance model actually a valid one? -- Brian D. Ripley, [EMAIL PROTECTED] 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 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
