[R] Non linear regression with complex equation

Rolf Turner rolf.turner at xtra.co.nz
Tue Feb 28 04:47:54 CET 2012


Your question is (completely) ill-posed.  What is your actual
model?  What you have said makes no sense at all as it stands.
(Minimal self-contained example .....)

     cheers,

         Rolf Turner

On 28/02/12 09:25, jeff_hawkes wrote:
> Hi all,
> Is it possible to model a function where the unknown parameter appears both
> in the fitted equation AND in the determination of other parameters?  E.g.
>
> y = a^2 + b/2 + k
>
> where a = 2/k  and b = k^2
>
> and the model needs to determine k?  I know this is a very simple equation
> (its just an example), the one I am modelling is much more complicated!
>
> k appears in the equation which the n.l.r model fits, but it also affects
> other parameters in the equation.  Please let me know if you know a way of
> achieving this.  I realise it is possible to set up a loop where the
> modelled value for k is fed back in to a and b, and the model is run again -
> but it seems like there should be a more elegant way within one run of the
> model.



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