optim(3, cost.f, x=x, y=y)
In the form given below, R interprets you call as equivalent to the following:
optim(par=3, fn=cost.f, gr=x, method=y)
Arguments will get passed via "..." when they have names that are different from names in the official argument list.
hope this helps. spencer graves
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)
## returns:
Error in pmatch(x, table, duplicates.ok) : argument is not of mode character
## uh, uh... may the problem is with the argument matching ?
optim(3, cost.f, method="BFGS", x, y)
## returns:
Error in log(A * x) : Argument "x" is missing, with no default
In addition: Warning message: bounds can only be used with method L-BFGS-B in: optim(3, cost.f, method = "BFGS", x, y)
Any suggestion ?
L.
PS: this was done with both R-1.7.1-patched and R-1.8.0-patched for Linux.
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