Hi, I am usign the smooth.spline function. I am not sure how the _df_ (degrees of freedom) parameter, if set, influences _lambda_ in eq: L = (y - f)' W (y - f) + lambda c' Sigma c Is _df_ substituting tr(Sigma), if defined, in the equation: r = tr(X' W X) / tr(Sigma), which is used to compute: lambda = r * 256^(3*spar - 1)? How _spar_ is set if not defined? /E Dipl. bio-chem. Eryk Witold Wolski @ MPI-Moleculare Genetic Ihnestrasse 63-73 14195 Berlin 'v' tel: 0049-30-83875219 / \ mail: witek96 at users.sourceforge.net ---W-W---- http://r4proteomics.sourceforg.net