I believe that if your try these starting values the sum of squares is considerably smaller
a=1.0851e-06 b=1.4596e-01 delta=9.1375e-01 something like SS= 0.005236471 vs SS= 0.01597071 ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
