On Wed, 1 Jul 2020 14:31:19 +0200 Luigi Marongiu <marongiu.lu...@gmail.com> wrote:
> the optimization actually got a worse outcome than the original >eyeball estimation Could you elaborate on the function you are trying to fit to your data? nls.lm takes a function returning a vector of residuals, that is, fn <- function(parameters, input, actual.output) { calculate.output(parameters, input) - actual.output } ...which means that you need a vector of input values and a vector of output values of the same length. In your example, > y = (p$a * x^2) / (p$b^2 + x^2) a and b are parameters. x seems to be the dependent variable (i.e. output of the process) and not the independent variable (i.e. input of the model function) like I had initially assumed. What is the input of your model function? -- Best regards, Ivan ______________________________________________ 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.