[R] two term exponential model

[Prof Brian Ripley]

On Mon, 8 Aug 2005, Deming Mi wrote:

> Does anybody know if there is an R function (package) to fit a two-terms
> exponential model like y = a*exp(bx) + c*exp(dx) where y is dependent
> variable and x is independent variable.  MATLAB has a Curve Fitting Toolbox
> to implement this fitting, but I don't know if there is an R package for
> this fitting.  Thank you!

See ?nls

>From my experience with such models the coefficients are often not 
well-determined and so you need a good starting point.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595