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Non linear regression using Levenberg-Marquardt method

2 messages · Marjorie Bourgoin, Thomas Lumley

Marjorie Bourgoin
# 
Hello,

I want to fit some non linear models with the Levenberg-Marquardt
algorithm. It doesn't seem to exist any function to do this in R ( well,
maybe one does, but I'm a new user, and the only documentation I have is
"An introduction to R").
I'd like to know if this function exists, maybe throught an additionnal
package.

I'd also like to know if if I can fit my models without giving initial
estimates of the parameters. The problem is that I have to fit four non
linear models with a lots of data sets, so I can't plot the data and
guess parameters values for each of them.

Thanks for all

Marjorie
Thomas Lumley
#
On Mon, 15 May 2000, Marjorie Bourgoin wrote:

            

      
      
      
    

        
The nls package fits many non-linear models. Some of them are
'self-starting'; they don't need starting values.  Even if your model
isn't one of them you might be able to work out how to make it
self-starting.

I don't think it uses a Levenberg-Marquardt algorithm, but that shouldn't
matter.

You could also code the model as a minimisation problem and feed it to
optim(), which also doesn't use a Levenberg-Marquardt model.


	-thomas

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