Hi Mario,
yes works great. Thanks!

2011/4/12 Mario Valle <mvalle@cscs.ch>

> Use a more realistic starting point instead of the default one:
>
> fit <- nls(yeps ~ p1 / (1 + exp(p2 - x)) * exp(p4 * x),
> start=list(p1=410,p2=18,p4=-.03))
>
> This works for me:
> > fit
> Nonlinear regression model
>  model:  yeps ~ p1/(1 + exp(p2 - x)) * exp(p4 * x)
>   data:  parent.frame()
>       p1        p2        p4
> 199.48276  16.28664  -0.01987
>  residual sum-of-squares: 560.6
>
> Number of iterations to convergence: 5
> Achieved convergence tolerance: 5.637e-07
>
> Ciao!
>                        mario
>
>
> On 12-Apr-11 18:01, Felix Nensa wrote:
>
>> fit = nls(yeps ~ p1 / (1 + exp(p2 - x)) * exp(p4 * x))
>>
>>
> --
> Ing. Mario Valle
> Data Analysis and Visualization Group            |
> http://www.cscs.ch/~mvalle
> Swiss National Supercomputing Centre (CSCS)      | Tel:  +41 (91) 610.82.60
> v. Cantonale Galleria 2, 6928 Manno, Switzerland | Fax:  +41 (91) 610.82.82
>
>


-- 
Felix Nensa

Luisenstr. 15-17
44787 Bochum
Germany

mail: felix.nensa@googlemail.com
mobile: +49 171 958 51 40

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