If you make the x-values more dense, e.g. with x<-seq(0,20,0.1) then your example works. Plotting your data might give a hint to why your example fails.... Btw: It is generally not a good idea to use F for a parameter because F usually means FALSE. Regards Søren
________________________________ Fra: [EMAIL PROTECTED] på vegne af Jon Loehrke Sendt: ti 10-06-2008 16:25 Til: r-help@r-project.org Emne: [R] fitting periodic 'sine wave' model I have been attempting to estimate the periodic contribution of an effect to some data but have not been able to fit a sine wave within R. It would be nice to start by being able to fit a sine wave with an amplitude and frequency. x<-seq(0,20,by=0.5) y<-2*sin(2*pi*.5*x) #amplitude =2, frequency=0.5 # This failed to converge r<-nls(y ~ A*sin(2*pi*F*x), start=list(A = 1, F = 1), trace=T) # even this gave a max iteration error r<-nls(y ~ A*sin(2*pi*F*x), start=list(A = 1, F = .5), trace=T) I have a feeling I am approaching this incorrectly. Thank you all very much for the guidance. Jon R 2.7.0 mac os 10.5 Jon Loehrke Graduate Research Assistant Department of Fisheries Oceanography School for Marine Science and Technology University of Massachusetts 200 Mill Road, Suite 325 Fairhaven, MA 02719 [EMAIL PROTECTED] T 508-910-6393 F 509-910-6396 ______________________________________________ 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. ______________________________________________ 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.
