[R] .Internal

[Berwin A Turlach]

G'day Kevin,

On Wed, 18 Mar 2009 21:46:51 -0700
<rkevinburton at charter.net> wrote:

> I was trying to find source for optimize and I ran across
> 
> function (f, interval, ..., lower = min(interval), upper =
> max(interval), maximum = FALSE, tol = .Machine$double.eps^0.25) 
> {
>     if (maximum) {
>         val <- .Internal(fmin(function(arg) -f(arg, ...), lower, 
>             upper, tol))
>         list(maximum = val, objective = f(val, ...))
>     }
>     else {
>         val <- .Internal(fmin(function(arg) f(arg, ...), lower, 
>             upper, tol))
>         list(minimum = val, objective = f(val, ...))
>     }
> }
> 
> Then I did a search for fmin and i came up with:
> 
> /* fmin(f, xmin, xmax tol) */
> SEXP attribute_hidden do_fmin(SEXP call, SEXP op, SEXP args, SEXP rho)
> 
> 
> So my question is where do I find the intermediary step between 
> 
> .Internal(fmin(function(arg) f(arg, ...), lower,  upper, tol))
> 
> and
> 
> SEXP attribute_hidden do_fmin(SEXP call, SEXP op, SEXP args, SEXP rho)

@Article{Rnews:Ligges:2006,
  author       = {Uwe Ligges},
  title        = {{R} {H}elp {D}esk: {Accessing} the Sources},
  journal      = {R News},
  year         = 2006,
  volume       = 6,
  number       = 4,
  pages        = {43--45},
  month        = {October},
  url          = http,
  pdf	       = Rnews2006-4
}

http://CRAN.R-project.org/doc/Rnews/Rnews_2006-4.pdf

> The number of arguments doesn't match up. I am guessing that lower
> and upper somehow get merged into the args. And rho is 'tol'. Right?

Unlikely.  In "Writing R Extensions" (and the functions I looked up),
'rho' usually denotes an environment that is used to evaluate
expressions in.  Typically (i.e. in cases that I had need to look at),
all arguments are rolled into the SEXP arg for internal functions.

HTH.

Cheers,

	Berwin