[R] 'optim' and extra argument to the objective function

[Thomas Lumley]

On Mon, 20 Oct 2003, Laurent Gautier wrote:

>
> Hello,
>
>
> I'd like to use optim, and give extra arguments to the objective
> function. The man page says that the '...' should let one do it,
> but I have a hard time to understand how.
>
> Example:
>
> x <- 1:10
> y <- rnorm(10)
> cost.f <- function(par, x, y) {
>  A <- par[1]
>  cost <- sum( (log(A*x) - log(y))^2)
>  return(cost)
> }
>
> optim(3, cost.f, x, y)


You need
  optim(3, cost.f, x=x, y=y)

As always, if you don't specify a tag for an argument it gets matched
positionally, in this case to the gr and method arguments of optim().

	-thomas