Dear Christian: That is not the problem, but thanks for your attempted help. I still don't know what the problem is. Has anyone encountered this while using "gnls" function in the package "nlme"?
thanks again for any help, Ravi. ----- Original Message ----- From: Christian Mora <[EMAIL PROTECTED]> Date: Wednesday, January 14, 2004 7:15 pm Subject: RE: [R] Generalized least squares using "gnls" function > Have you tried removing tol=1.e-07 or changing the value considering > that the error is Object "." not found > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On > Behalf Of Ravi Varadhan > Sent: Wednesday, January 14, 2004 6:11 PM > To: [EMAIL PROTECTED] > Subject: [R] Generalized least squares using "gnls" function > > > Hi: > > I have data from an assay in the form of two vectors, one is > response > and the other is a predictor. When I attempt to fit a 5 parameter > logistic model with "nls", I get converged parameter estimates. I > also > get the same answers with "gnls" without specifying the "weights" > argument. > > However, when I attempt to use the "gnls" function and try to > estimate > the variance function, as a power function, I get the following > error > message: > > > ans51g <- gnls(log(b51) ~ p0 + p1/(1 + exp(-(log(dose)- > p2)/p3))^p4, > start=list(p0=3,p1=1,p2=4,p3=2,p4=1.5),control=gnlsControl(tol=1.e- > 07),weights=varPower()) > Error in eval(expr, envir, enclos) : Object "." not found > > > > What am I doing wrong here and how can I do a GLS analysis with a > variance function that is estimated from the data? > > Here is my data: > > > b51 <- c(17447.60674, 7060.37234, 2872.53012, 796.40426, > 454.47222, 260.22340, 120.11905, 83.40196, 51.45745, > 36.87912, 26.73256, 25.18681, 17.97674) > > dose <- c( 1.000000e+04, 1.000000e+03, 2.500000e+02, > 6.250000e+01, > 3.125000e+01, 1.562500e+01, 7.812500e+00, 3.906250e+00, > 1.953125e+00, 9.765625e-01, 4.882813e-01, 2.441406e-01, 1.000000e-03) > > thanks for the help, > Ravi. > > ______________________________________________ > [EMAIL PROTECTED] mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html