 Dear R-helpers,

I'm a new R-user and I was trying to gain some experience with the GNLS function of the NLME package.

 This is an extract from my dataset (it's a 432x6 data.frame) called "input", in the first column I have the values that I need to fit, while the remaining columns are input variables for the theoretical model, the function "mymodel" (which returns a 432x1 vector of fitted values):

V0V1V2V3 V4 V5
0.56374863838.6875400.1041095890.0572495640
1.47392252639.125400.2767123290.0553929370
0.51704068441.0625450.1808219180.0532145910
1.38181318737.5625400.3534246580.0505213210

and this is my call of gnls:

fm1 <- gnls(V0 ~ mymodel(V1,V2,V3,V4,V5,par1,par2,par3,par4,par5,par6,par7,par8), data=input,start=list(par1=0.2,par2=0.4,par3=0.8,par4=0.2,par5=10,par6=0.8,par7=0.9,par8=-0.5))

and I get the following error:

Error in `[.data.frame`(eval(model, data.frame(data, getParsGnls(plist,  : 
  undefined columns selected

 My guess is that R is not able to create that data.frame since "getParsGnls", an internal function of gnls, does not provide its output (obviously the error is mine, but I can't clearly identify it). Indeed, in the previous lines of the gnls code, I don't have any problems when R creates a data.frame using the dataframe "data" and "pars", as follows:

res <- eval(model, data.frame(data, pars))

I would be grateful to receive any help or hint.

Best regards,
Louis Salomon

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