This problem is a known bug of the macintosh() device. Usually by simply enlarging the window solves the problem of "negative length". It is written in the Mac Faq and I'm trying to fix this too for the next release. Sorry about that. Stefano On Mercoledì, maggio 30, 2001, at 11:12 , Andrew Beckerman wrote: > I am getting a error message: > > Error in plot.xy(xy,......: negative length vectors not allowed.