Without an example, I'm not sure how much help I can be. Does your
Variogram calculation return a single value that could be minimized? Or
could it be coerced to be so?
I would suggest, if you haven't done so, a look at ?nlm and ?nlminb.
Alternatively, the CRAN package 'optimx' serves as a wrapper to many
optimization algorithms and offers methods to compare them side-by-side.
Good luck,
Jon
--------------------------------------
Jonathan P. Daily
Technician - USGS Leetown Science Center
11649 Leetown Road
Kearneysville WV, 25430
(304) 724-4480
"Is the room still a room when its empty? Does the room,
the thing itself have purpose? Or do we, what's the word... imbue it."
- Jubal Early, Firefly
r-help-boun...@r-project.org wrote on 12/20/2010 09:39:49 AM:
> [image removed]
>
> [R] How to optimize function parameters?
>
> zbynek.jano...@gmail.com
>
> to:
>
> r-help
>
> 12/20/2010 10:43 AM
>
> Sent by:
>
> r-help-boun...@r-project.org
>
>
> Hi,
>
> I have a dataset and I want to fit a function to it.
> The function is variogram model (http://en.wikipedia.org/wiki/Variogram)
> The variogram model is defined by three parameters and I want them to be
> automatically optimized for real time data.
> I tried to use gafit {gafit} for this, but there are some data
> configuration, where optimal results given by gafit() are negative,
which is
> not correct and cannot be used for further calculating. gafit() does not
> enable me to set a range of possible results (at least I did not
succeded in
> doing so), therefore I am looking for another solution (Powell´s
gradient
> descent possibly?).
>
> Can anyone give me a hint where to look?
>
> Thanks
>
> Zbynek
> --
> View this message in context: http://r.789695.n4.nabble.com/How-to-
> optimize-function-parameters-tp3095603p3095603.html
> Sent from the R help mailing list archive at Nabble.com.
>
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