On Thu, 18 Oct 2007, Nicholas Lewin-Koh wrote: > Hi, > Following up on my own post, if in gnlsControl I specify > opt='optim' gnls exits quite nicely, with an error, which > is what I would expect. Is this a bug in nlminb?
Possibly, but complex algorithms can loop for non-bug reasons. I don't feel motivated to explore it in detail, but if you want/are able to, please let us know what you find. I have always found optim to work better in package nlme than nlminb (and I know others who have the same experience). > > Nicholas > > > tt<-gnls(response~SSllogis(conc,A,B,xmid,scal),tdat,start=start,weights=varPower(),verbose=TRUE,control=gnlsControl(opt='optim')) > **Iteration 1 > GLS step: Objective: 29.04254varStruct parameters: > power > 0.3373206 > > NLS step: RSS = 0 > model parameters:-0.799941 8.99983 -0.522623 212.314 > iterations: 2 > > Convergence: > params varStruct > 1.172208 1.000000 > Error in optim(c(coef(gnlsSt)), function(gnlsPars) -logLik(gnlsSt, > gnlsPars), : > initial value in 'vmmin' is not finite > In addition: Warning messages: > 1: In log(xmid) : NaNs produced > 2: In log(xmid) : NaNs produced > 3: In log(xmid) : NaNs produced > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
