i need to do a quadratic plateau. I saw the code and try to put my datas, but i had some errors. This is my code , for (mun in 1:dm[1]){ # for (mun in 8:dm[1]){ if(nu[mun]>= nmin) { y1=arquivov[mun,ncv[mun]:27] vy = as.numeric(y1) x=seq(1:nu[mun]) cr=lm(vy~x+I(x^2)) ca_q[mun]=cr$coefficients[[1]] cl_q[mun]=cr$coefficients[[2]] cq_q[mun]=cr$coefficients[[3]] alpha_q=as.numeric(ca_q[mun]) beta_q=as.numeric(cl_q[mun]) gamma_q=as.numeric(cq_q[mun]) fm <- nls(vy ~ Mean(x, alpha, beta, gamma), start=list(alpha=alpha_q, beta=beta_q, gamma=gamma_q),control = list(maxiter = dm[1])) fm summary(fm) plot(vy ~ x) lines(fitted(fm) ~ x) with(as.list(coef(fm)), abline(v = -beta/(2 * gamma))) } else{ }} > vy [1] 77.25989 58.00000 58.00000 58.00000 109.68317 58.00000 80.00000 > 80.00000 71.33333 69.66667 68.00000 65.33333[13] 58.00000 57.00000 > 57.00000 57.00000 57.00000 67.00000> alpha_q[1] 67.69373> beta_q[1] > 1.321098> gamma_q[1] -0.1129059
Error in nls(vy ~ Mean(x, alpha, beta, gamma), start = list(alpha = alpha_q, : singular gradient [[alternative HTML version deleted]] ______________________________________________ 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.