Message-ID: <Pine.GSO.4.21.0005150822060.3462-100000@mail.biostat.washington.edu>
Date: 2000-05-15T15:28:35Z
From: Thomas Lumley
Subject: Non linear regression using Levenberg-Marquardt method
In-Reply-To: <391FC454.FCD3E256@salome.saclay.cea.fr>
On Mon, 15 May 2000, Marjorie Bourgoin wrote:
> 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.
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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