> My goal is to find a model (GAM with thin plate splines) in R. > I found the function "gam" in the R-library "mgcv", but it just fits > one-dimensial splines. - Unless you have an exceedingly ancient version of mgcv (<0.6), it *does* allow spline smooths of more than one variable. ?gam contains a couple of examples as does ?gam.side.conditions. Simon