You problem is x^c for x = 0. If you intended only c > 1, try a starting value meeting that condition (but it seems that the optimal c is about 0.27 is you increase x slightly).
Why have you used ~~ ? (Maybe because despite being asked not to, you sent HTML mail?) On Tue, 15 Aug 2006, Xiaodong Jin wrote: > Is there anyway to change any y[i] value (i=2,...6) to make following NLS > workable? > > x <- c(0,5,10,15,20,25,30) > y <- c(1.00000,0.82000,0.68000,0.64000,0.66667,0.68667,0.64000) > lm(1/y ~~ x) > nls(1/y ~~ a+b*x^c, start=list(a=1.16122,b=0.01565,c=1), trace=TRUE) > > #0.0920573 : 1.16122 0.01565 1.00000 > #Error in numericDeriv(form[[3]], names(ind), env) : > # Missing value or an infinity produced when evaluating the model > > > --------------------------------- > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@stat.math.ethz.ch 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. > -- 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-help@stat.math.ethz.ch 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.