[R] Generating start values for nls

From: Paul Brewin <pebrewin_at_sdsc.edu>
Date: Fri 20 Oct 2006 - 04:51:56 GMT

Dear R-listers,

I would like to know if there is a way to programmatically generate parameter start values for the model y~(a*exp(b*x)+c*exp(d*x)) in R. I've scoured the help files and archives for nls() and similar searches, and have read Fox 2002 - the best advice has been to make estimates from a priori knowledge of the data. However, in the Matlab CurveFit tool, reliable start values are somehow estimated 'heuristically', as is claimed in their help files. Is there a similar R routine than may produce reasonable start values?

Many thanks,
Paul Brewin

Paul E Brewin (PhD)
Center for Research in Biological Systems University of California San Diego
9500 Gilman Drive MC 0505
La Jolla CA, 92093-0505
USA   Ph: 858-822-0871
Fax: 858-822-3610

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