Hello there, I am using the Tps function to fit a spline to my data which is measurements of a sedimentary layer on an xy plane to see how the thickness of the layer changes. I was wondering if it was possible to change the Tps code so that no minus values are calculated by the spline as these are obviously unfeasible. Any help would be much appreciated, Thanks, Sam -- View this message in context: http://r.789695.n4.nabble.com/Minus-values-in-Tps-tp2336949p2336949.html Sent from the R help mailing list archive at Nabble.com.