[R] Where to find source of C_pbinom?

Marius Hofert marius.hofert at math.ethz.ch
Wed Aug 27 14:34:11 CEST 2014

Dear Sarah, Dear David,

thanks for helping. I know the FAQ and I know the R News article, but
I still couldn't figure it out. First, pbinom calls
.External(C_pbinom,...). Grepping for C_pbinom reveals... nothing
(except the appearance in .External). Going to ./src/main/names.c
reveals "{"pbinom", do_math3, 5, 11, 3+2, {PP_FUNCALL, PREC_FN, 0}},",
so the next step is to grep for do_math3 (which also applies for
"dbeta", "pbeta",..., "qnbinom_mu"). There is a connection to pbinom
again in ./src/main/arithmetic.c (SEXP attribute_hidden do_math3):
Math3_2(args, pbinom) is called. src/library/stats/src/distn.c then
shows that "Math3_2(args, pbinom)" is called. Since we just already
grepped for Math3_2, the trip ends here.

So how can one find the source code of pbinom() in this case?



On Wed, Aug 27, 2014 at 7:28 AM, Sarah Goslee <sarah.goslee at gmail.com> wrote:
> R FAQ 7.40
> http://cran.r-project.org/doc/FAQ/R-FAQ.html#How-do-I-access-the-source-code-for-a-function_003f
> Sarah
> On Tuesday, August 26, 2014, Marius Hofert <marius.hofert at math.ethz.ch>
> wrote:
>> Dear expeRts,
>> I would like to find out how R computes pbinom(). A grep in the
>> source code reveiled src/library/stats/R/distn.R:146:
>> .External(C_pbinom, q, size, prob, lower.tail, log.p), so
>> 'C_pbinom' refers to compiled C/C++ code loaded into R. Where can
>> I find the source code of C_pbinom?
>> Cheers,
>> Marius
> --
> Sarah Goslee
> http://www.stringpage.com
> http://www.sarahgoslee.com
> http://www.functionaldiversity.org

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