[R] Generating start values for nls

[Paul Brewin]

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