Don't use nls for exact fits, as that's not what it is intended for, and you are trying to achieve a fit to machine accuracy with rounding errors.
You will find several discussions of this in the archives. On Mon, 10 Feb 2003, Gregory BENMENZER wrote: > I want to estimate parameters of the model y=a/x with x=1:10 and y=3/x. > I tested the NLS function. > > Could you tell me why it doesn't converge ? > > Regards, > > Gr�gory Benmenzer > > > x=1:10 > > y=3/x > > nls(y~a/x, start=list(a=2), control=nls.control(maxiter=100)) > Error in nls(y ~ a/x, start = list(a = 2), control = nls.control(maxiter = 100)) : > number of iterations exceeded maximum of 100 -- 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 ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
