I have the following data set, and I have to find the line of best fit using this equation, y = a*(1 - exp(-b*x)).
samples = seq(1,20,by=1) species = c(5,8,9,9,11,11,12,15,17,19,20,20,21,23,23,25,25,27,27,27) plot(samples,species, main = "Accumulation Curve for Tree Species Richness", xlab = "Samples", ylab = "Number of Species") curve((y = 27*(1 - exp(-.15*x))),from=0,to=20,add = T) I tried to find the best fit curve using: fit = nls(species ~ a *(1 - exp(-b*x)),start = list(a = 27, b = .15) but I get a "parameters without starting value in 'data': x" and I don't have any idea what this means, or how to fix the above code. -- View this message in context: http://r.789695.n4.nabble.com/Generating-a-best-fit-line-for-non-linear-data-tp3482193p3482193.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.