Steve Oswald wrote: > > I'm analysing growth rates using a gompertz (logistic) curve and am > attempting > to fit parameters for all of my study birds using nlsList. > > I've been looking for an option in nlsList to set min and max limits for > parameter values during estimation, although I have failed to find any > under > 'control'. >
If you want to constrain to positive parameters only, as in pharmacology, fitting the logs of the parameters might help. For more general constraints, check the examples in optim. Dieter Hi All I'm analysing growth rates using a gompertz (logistic) curve and am attempting to fit parameters for all of my study birds using nlsList. I've been looking for an option in nlsList to set min and max limits for parameter values during estimation, although I have failed to find any under 'control'. Other users seem to have reported that using control in the port algorithm (as in an nls fit) failed to work and it didn't work in my case either. Is there such a control for nlsList? I did fashion a selfStart function with a work-around loop in it. This subsetted the data by ID and performed separate nls fits with parameters constrained by the port algorithm. My objective was to use nlsList as an object for an nlme fit, so I was thinking of pasting together the details of the fits from my slefStart function into an object of class "nlsList" "lmList" but wasn't sure if this would work or was even appropriate. Thanks for your help Steve Dr. Steve Oswald Penn State Berks [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. -- View this message in context: http://n4.nabble.com/nlsList-nlme-control-of-min-and-max-parameter-bounds-tp1746242p1746347.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.