I get a different error now: > nls(weight ~ cbind(1, exp(gamma*week)), weightData, start = list(gamma= >0.2), alg = "plinear") Error in nls(weight ~ cbind(1, exp(gamma * week)), weightData, start = list(gamma = 0.2), : step factor 0.000488281 reduced below 'minFactor' of 0.000976562 The help file says: ........When start is missing, a very cheap guess for start is tried (if algorithm != "plinear").
So I removed 'plinear' from the call and got the following: nls(weight ~ cbind(1, exp(gamma*week)), weightData,start = list(gamma=0.2),trace=TRUE) 1466475181 : 0.2 Error in qr.qty(QR, resid) : 'qr' and 'y' must have the same number of rows Felipe D. Carrillo Supervisory Fishery Biologist Department of the Interior US Fish & Wildlife Service California, USA http://www.fws.gov/redbluff/rbdd_jsmp.aspx >________________________________ >From: Gabor Grothendieck <ggrothendi...@gmail.com> >To: Felipe Carrillo <mazatlanmex...@yahoo.com> >Cc: Bert Gunter <gunter.ber...@gene.com>; "r-help@r-project.org" ><r-help@r-project.org> >Sent: Thursday, July 12, 2012 12:14 PM >Subject: Re: [R] nls question > >On Thu, Jul 12, 2012 at 3:02 PM, Felipe Carrillo ><mazatlanmex...@yahoo.com> wrote: >> Thanks Bert, I increased the number of iterations: >> >> M_model <- nls(weight ~ alpha + >> beta*exp(gamma*week),control=nls.control(maxiter=200), weightData, >> start = c(alpha = 0.0, beta = 1, gamma = 0.2), trace = TRUE) >> >> But now the 'start' argument seems to be the problem. >> Looking at the model coefficients: >> alpha beta gamma >> -49.108008320 52.394172340 0.005269907 >> If I change the alpha and beta values inside start..I still get the error... > >Try using the plinear algorithm: > >nls(weight ~ cbind(1, exp(gamma*week)), weightData, start = list(gamma >= 0.2), alg = "plinear") > > >-- >Statistics & Software Consulting >GKX Group, GKX Associates Inc. >tel: 1-877-GKX-GROUP >email: ggrothendieck at gmail.com > > > [[alternative HTML version deleted]]
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