I am not sure how you simplified the model to: y = a + b(1 - exp(kl)) - b exp(-kx)
I tried simplifying it but only got to: y = a + b - b * exp(kl) * exp(-kx) I agree that the model must not be identifiable. That makes sense, especially given that removing either a or l makes the model work. Can you please further explain the math though as I am not understanding it? I do not see you obtained your equation and when I tried to solve using your equation I got quite different numbers. Thank you. -- View this message in context: http://r.789695.n4.nabble.com/nls-not-solving-tp3328647p3328862.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
