Hi, I am learning R by reading R source code. Here is one question I have
about the optim function in R.

The context : In the optim.R, after all the prep steps, the main function
call call is made via :

.External2(C_optim, par, fn1, gr1, method, con, lower, upper).

So, it seems to me, to follow what is going on from here, that I should
read the optim function in \src\library\stats\src\optim.c

where it has this signature :

SEXP optim(SEXP call, SEXP op, SEXP args, SEXP rho)

I am not sure I follow here : In the .External2 call, we have 7 parameters
:  par, fn1, gr1, method, con, lower, upper; This does not seem to match
the signature of

SEXP optim(SEXP call, SEXP op, SEXP args, SEXP rho)

However, it seems (from the source code) that the 7 parameters are somehow
embedded in the 'args' parameter. I am not sure what is going on...Am I
missing something?

Thanks much!!!

Best,

Zhiyuan

	[[alternative HTML version deleted]]

