I think its your parameterization that is problematic. ED50^hill is tough for it to work with since both are varying.
Try reparameterizing using ED50hill = ED50^hill as a parameter so that the parameters become Emax, ED50hill and hill. You can back transform afterwards. On 10/16/07, Lanre Okusanya <[EMAIL PROTECTED]> wrote: > Hello all, I am having a problem with nls. I have such data as shown below, > foo<- > Dose var > 0 0.000000 > 100 -1.318178 > 200 -1.562425 > 400 -3.579960 > 1200 -3.788662 > > however, when I call nls as shown below, > > >foo.nls<-nls(var~Emax*(Dose^hill)/((EC50^hill)+(Dose^hill)), > + start=list(Emax=-4,EC50=269,hill=1),trace=T,data=foo) > > i get the response below. > > 1.759088 : -4 269 1 > Error in numericDeriv(form[[3]], names(ind), env) : > Missing value or an infinity produced when evaluating the model > > > if i remove the hill variable, it works. can someone help me out with > what I am coding wrong. > > Thanks, > > > > Lanre > > ______________________________________________ > 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.
