Many people could help you, but the question is too general. In
brief, it means that the algorithm has found a place where the
(estimated?) matrix of first or second partial derivatives is of reduced
rank, and it refuses to do more. For such problems, I often use
"optim".
If you need more specifics, PLEASE do read the posting guide!
"http://www.R-project.org/posting-guide.html", prepare a very simple
example of what you get, and submit that to this list. Many people find
answers to their questions in the process of preparing a post following
this guide, and those that don't, I believe, are more likely to get more
informative replies.
spencer graves
Guillaume STORCHI wrote:
>Hello,
>
>I have a problem with nls() when I want to fit a model with more than two
>parameters to be fitted which are written as start=list(a1=,a2=,a3=,...).
>Everytime, it displays:'error... singular gradient'
>it's a real pain!!!
>
>Hope sb knows something about this
>
>Thanks
>
>GS
>
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>PLEASE do read the posting guide!
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>
>