Ranney, Steven <steven.ranney <at> montana.edu> writes: > > and I'm trying to fit a simple Von Bertalanffy growth curve with program: > > VonB=nls(TL~Linf*(1-exp(-k*(age-t0))), data=box5.4, > start=list(Linf=1000, k=0.1, t0=0.1), trace=TRUE) ... > Everything works as it should right up until the confint(VonB) statement. When I ask > for the confidence intervals, R goes through the process then stops and gives > > "Error in prof$getProfile() : > step factor 0.000488281 reduced below 'minFactor' of 0.000976562". > > However, when I use nls.control=(minFactor=0.000001) OR nls.control(minFactor=0.000001),
In my experience, it never helps to reduce the control factors once this error comes up; it is a problem that by profiling you hit a boundary where convergence problems are serious. Suggestions: first, try with some smaller p-value, e.g. 0.8 or 0.7 instead of the default of 0.95; profiling will stay in safer region. It may be possible to use algorithm "port" in combination with lower/upper, but I am not sure if this is honoured by profile. Dieter ______________________________________________ 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.