[R] Error message from nlmer

Kari Ruohonen kari.ruohonen at utu.fi
Thu Oct 25 14:31:44 CEST 2007


I have R 2.6.0 with updated lme4 and Matrix packages, and I am trying to
fit a nonlinear multilevel model. I get the following error message:

Error in nlmer(f ~ grModel(x, w, Tmin, Tmax, Topt, kopt, m) ~ kopt |
flat,  : 
  gradient attribute of evaluated model must be a numeric matrix

and I wonder what this may indicate.

The nonlinear model I try to fit is as follows:

> grModel

and my call of nlmer is as follows:


'flat' is a factor with 11 levels.

My start values are from nls that fits the model with no errors. The
call I have used is as follows:


The examples given on the help page of nlmer run with no errors.

I would appreciate any hints and help to track the problem indicated by
the error message.



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