Hi everyone, I thought that for a selfStart function, these two should be exactly equivalent > nls(Aform, DF) > nls(Aform, DF, start=getInitial(Aform, DF)) but in this example that is not the case in R (although it is in S-plus V6.2) ------------------------------ SSbatch<-selfStart( model=function(Batch, Coeffs) { Coeffs[Batch]
} ,initial=function(mCall, data, LHS) { # Estimate coefficients as mean of each batch xy <- sortedXyData(mCall[["Batch"]], LHS, data) Batch <- data[[as.character(mCall[["Batch"]])]] # check Batch is successive integers starting at 1 if ((min(xy$x) !=1) | (any(diff(xy$x)!=1))) stop( "Batch is not a successive integers sequence") Lval <- list(xy$y) names(Lval) <- mCall["Coeffs"] Lval } ) DF <- data.frame(A=c(0.9, 1.1, 1.9, 2.0, 2.1, 2.9, 3.0), Batch=c(1,1,2,2,2,3,3)) Aform <- formula(A~SSbatch(Batch,cA)) nls(Aform, DF, start=getInitial(Aform, DF)) nls(Aform, DF) ------------------------------------ Don't ask why I'd want such a silly selfStart, that's a long story. I guess wherever I would have used nls(Aform, DF) I could use nls(Aform, DF, start=getInitial(Aform, DF)) but that seems clumsy. Can anyone point out my mistake? Or is this a limitation of nls in R (I hesitate to use the b*g word). Thanks in advance, Keith Jewell ---------------------------------- I don't think it's relevant but, for completeness: > sessionInfo() version 2.7.0 (2008-04-22) i386-pc-mingw32 locale: LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United Kingdom.1252;LC_MONETARY=English_United Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252 attached base packages: [1] stats graphics grDevices datasets tcltk utils methods base other attached packages: [1] xlsReadWrite_1.3.2 svSocket_0.9-5 svIO_0.9-5 R2HTML_1.58 svMisc_0.9-5 svIDE_0.9-5 loaded via a namespace (and not attached): [1] tools_2.7.0 VGAM_0.7-7 ______________________________________________ R-help@r-project.org 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 provide commented, minimal, self-contained, reproducible code.