Re: [R] Error in nlsModel

2018-10-08 Thread William Dunlap via R-help
Weibull<-function(tet1, tet2,x){ 1-exp(-exp(tet1+tet2*log10(x))) } range(effectdata_without_controls$conc) # 0.000135696 0.000247044 range(effectdata_without_controls$effect) # [1] -7.010672 100.240287 nls(effect ~ Weibull(tet1, tet2, conc)) Your Weibull function has a range of

Re: [R] Error in nlsModel

2018-10-08 Thread ProfJCNash
I'm not the author of nlsModel, so would prefer not to tinker with it. But "singular gradient" is a VERY common problem with nls() that is used by nlsModel as I understand it. The issue is actually a singular Jacobian matrix resulting from a rather weak approximation of the derivatives (a simple f

Re: [R] Error in nlsModel

2018-10-08 Thread PIKAL Petr
ers Petr > -Original Message- > From: R-help On Behalf Of Belinda Hum Bei Lin > Sent: Monday, October 8, 2018 11:15 AM > To: r-help@r-project.org > Subject: [R] Error in nlsModel > > Hello, > > It is my first time using R studio and I am facing the error of &g

[R] Error in nlsModel

2018-10-08 Thread Belinda Hum Bei Lin
Hello, It is my first time using R studio and I am facing the error of "Error in nlsModel(formula, mf, start, wts) : singular gradient matrix at initial parameter estimates" when I try to run my script. From what I read online, I understand that the error might be due to the parameters. However,