G'day Kevin, On Mon, 23 Mar 2009 18:48:16 -0400 <rkevinbur...@charter.net> wrote:
> Sorry to be so dense but the article that you suggest does not give > any information on how the arguments are packed up. I look at the > call: > > val <- .Internal(fmin(function(arg) -f(arg, ...), lower, upper, tol)) > > and then with the help of this article I find do_fmin in optimize.c: > > SEXP attribute_hidden do_fmin(SEXP call, SEXP op, SEXP args, SEXP rho) Sorry for not being clear enough. Yes, the article tells you how to find out that do_fmin is (eventually) called when you call optimize on the command line. I thought that this was one of your questions. > Again there doesn't seem to be any coorespondance between lower, > upper, tol and the arguments to do_fmin. So I am missing a step. As far as I know, .Internal has the same interface as .External. So a study of "Writing R Extensions" should give insight regarding this step. In particular Chapter 5 (System and foreign language interfaces) -> Section 5.10 (Interface functions .Call and .External) -> Section 5.10.2 (Calling .External). Essentially, all arguments to a C function called via .Internal or .External are passed as a single SEXP; this allows to pass an unlimited number of arguments to a C function as all other interfaces to native routines (.C, .Call, .Fortran) have some limit, albeit a rather generous one, on the number of arguments that can be passed to the native routine. I believe you can think of that single SEXP as a list containing the individual arguments. Accessing those arguments one by one involves macros with names like CDR, CAR, CADR, CADDR, CADDDR, CAD4R and so forth. As I understand it, if you are fluent in Lisp (Scheme?) and how components of a list are referred to in that language, then you have no problems with understanding the names of those macros. Since I never became comfortable with those languages, I restrict myself to .C and .Call; YMMV. HTH. Cheers, Berwin =========================== Full address ============================= Berwin A Turlach Tel.: +65 6516 4416 (secr) Dept of Statistics and Applied Probability +65 6516 6650 (self) Faculty of Science FAX : +65 6872 3919 National University of Singapore 6 Science Drive 2, Blk S16, Level 7 e-mail: sta...@nus.edu.sg Singapore 117546 http://www.stat.nus.edu.sg/~statba ______________________________________________ R-help@r-project.org 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.