The LENNS package (’Lyapunov Exponents for Noisy Nonlinear Systems’) was originally standalone f77, but then it got merged into the FUNFITS package for S-plus. FUNFITS is still available (see below) but is now ’frozen’ meaning that it probably won’t work with a current version of S-plus. Most of its functionality has been incorporated into the fields package for R that can be gotten from CRAN ( The rest -- neural networks, global and local Lyapunov exponents -- is here. LENNS and nnreg for R/Windows. This is not really a package, and it only works under Windows. Create a folder c:lenns and then extract the contents of into the lenns folder using folder names. This will create a folder tree c:lennschtml,c:lennsexec, etc. It is not in shape to be installed from within R (that used to work, but not since the rules changed with R 2.0) -- you will need to source() code from within an R session. The file readme.lenns tells you what to do. There is a set of html help pages that can be accessed from lenns/html/00Index.html. Sorry, this is the best I can do right now. If you have trouble getting it to run, let me know. If you unzip it into c:lenns, it should work ”out of the box” after you source lenns.R.