On Fri, 21 Jul 2006, N. Goodacre wrote:
Dear R mailing group,
>
> The second parameter for the function optim()is a function whose
> parameters are to be optimized. The description of this function given in
> the help file is the following:
>
> fn: A function to be minimized (or maximized), with first
> argument the vector of parameters over which minimization is
> to take place. It should return a scalar result.
>
> Let's say the second argument is x, a vector of x values
But it says `parameters'. Please look at the examples on that help page.
optim is concerned with optimizing functions of more than one parameter.
In a statistical setting 'x' may be the data, but e.g. for fitting a gamma
distribution c(scale, shape) are the parameters.
> I would have thought that fn should return a vector full of y values for
> the x values entered as the second argument. If the function just takes one
> value at a time and outputs a scalar, how can I specify for fn which x
> value, of the vector x, to take?
>
> Sincerely,
>
> Norman Goodacre
>
> ______________________________________________
>
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>
https://stat.ethz.ch/mailman/listinfo/r-help> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html> and provide commented, minimal, self-contained, reproducible code.
>
--
Brian D. Ripley,
[hidden email]
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
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https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide
http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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