[R] nl regression with 8 parameters, help!

From: Guillaume STORCHI <nioniodesbois_at_yahoo.fr>
Date: Thu 24 Mar 2005 - 02:28:41 EST

I'm doing a non linear regression with 8 parameters to be fitted:




   First, I fitted my curve on my data by guessing the parameters' values ("by hand"), and wrote them.

   Then, I ajusted my model only with two parameters (whereas the others were fixed with previously found values, I did it the same way for all parameters.

   Finally, I got 8 fitted values that I enventually embedded in my nls() function, like above, yet R talled me:
"Error in nlsModel(formula, mf, start) : singular gradient matrix at initial parameter estimates"

should I use optim() or optimize()?
How could I perform it?

Thanks for help

Guillaume Storchi

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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Thu Mar 24 02:36:07 2005

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