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 > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > 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, [EMAIL PROTECTED] 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 ______________________________________________ R-help@stat.math.ethz.ch mailing list 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.