On Mon, Nov 8, 2010 at 5:15 PM, Peter Langfelder <peter.langfel...@gmail.com> wrote:
> If you also need the z coordinate, it simply the mean of the matrix Z. > > zCenter = mean(Z) How can that be right? Suppose your mountain is very flat, so that your mountain is effectively a cube. The Z values are all the same, and so their mean is the same. However the centre of mass is, by symmetry, clearly at height/2. Similarly suppose your mountain matrix is one large cell value and all the rest are near zero - the mean Z will be close to zero but the centre of mass will be almost half way up the single cell value, because all the near-zeros contribute nothing to the centre of mass position. Barry ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
