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Any help is very much appreciated. I've tried the different algorithms, different starting values and tried to use optim to minimise the residual sum of squares, all to no avail. Examining lots of plots is probably a good place to begin.Cheers,BertBert GunterGenentech Nonclinical Biostatistics-----Original Message-----From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] OnBehalf Of CorradoSent: Wednesday, March 31, 2010 6:13 AMCc: r-help See if it solves your problem.

There are nonlinear least-squares problems with well-defined solutions that have rank-deficient or nearly rank-deficient Jacobians at many points. Kind regards, Neal Quoting "Ben Bolker [via R]" <[hidden email]>: > > > > bsnrh leeds.ac.uk> writes: > >> >> >> Hi Ben, >> >> Your book refers So, while you know a lot about the ratio b/c, you know nothing at all about b or c individually. Have I just fundamentally misunderstood how to use SSasymp?

Does the local network need to be hacked first for IoT devices to be accesible? Mullen offers an R frontend to a Fortran LM implementation of the MINPACK package. The solutionis unique and the rapidity of convergence is practically independentfrom the selection of start conditions (with a reasonable selection ofstart conditions at least). Perhaps you know T?

In a saturating curve, the rate constant is determined from the curvature. Look: # indentifiability No <- 100; a <- 1; b <- -1; T <- 2 Ne <- seq(1, 10, l=8) curve(No*(1-exp(a*(b*x-T))), 0, 10) abline(h=No*(1-exp(a*(b*0-T)))) # intercept C <- a*b; D <- For what its worth, in addition to the explanations given, if you are trying this on an artificial data set, according to the nls help page found at: http://stat.ethz.ch/R-manual/R-patched/library/stats/html/nls.html R's nls Peter Ehlers > Thanks, > > Felix > > [[alternative HTML version deleted]] > > ______________________________________________ > [hidden email] 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

LUTON Grokbase › Groups › R › r-help › March 2010 FAQ Badges Users Groups [R] Error "singular gradient matrix at initial parameter estimates" in nls CorradoMar 30, 2010 at 11:03 Does the code terminate? Electronics Design Multisim Data Acquisition ADwin Delphin Measurement Computing WinWedge Data Visualisation DADiSP Origin Laboratory Applications ChemBio3D ChemBioDraw ChemBioOffice ChemDraw Maths and Simulation Micro Saint Qualitative Analysis MVSP ProSuite QDA Miner before running nls.

My R shell is pasted below f <- function(x,a,b) {a * exp(b * x)} > x [1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 kn).Can anyone help me with suggestions? Get 2 lines yanked or 1 line yanked confirmation Is Vrindavan Krishna different from Dvaraka Krishna? The only other posts I saw with that had more variables, I tried increasing the number of iterations but that did not succeed.

This isn't the Rogers equation, although I am not familiar with that particular one. I've spent over a week looking for bugs in my code elsewhere till I noticed that the main bug was in the model :) share|improve this answer answered Jul 15 '11 before running nls. > > On Wed, Apr 28, 2010 at 7:43 AM, bsnrh leeds.ac.uk> wrote: > > > > Hello, > > > > I am trying to Together with Kate I developed a function nlsLM that has the gee wizz formulaic interface of nls, but it calls LM instead of Gauss-Newton.

up vote 5 down vote favorite 3 I have some basic data on emission reductions and cost per car: q24 <- read.table(text = "reductions cost.per.car 50 45 55 55 60 62 model1<-nls(Flux~b*Par/(c+Par)-a, data = curve1, start=list(a=180, b=-200, c=-2000)) plot(Flux~Par,curve1) curve(predict(model1,newdata=data.frame(Par=x)),add=TRUE) summary(model1) # Formula: Flux ~ b * Par/(c + Par) - a # # Parameters: # Estimate Std. You can still solve for the minimum norm solution, which is unique, but can cause computational problems because it involves a rank determination. All Rights Reserved.

Cantonale Galleria 2, 6928 Manno, Switzerland | Fax: +41 (91) 610.82.82 > > -- Felix Nensa Luisenstr. 15-17 44787 Bochum Germany mail: [hidden email] mobile: +49 171 958 51 40 Gabor Grothendieck Threaded Open this post in threaded view ♦ ♦ | Report Content as Inappropriate ♦ ♦ Re: NLS "Singular Gradient" Error In reply to this post by bsnrh