[R] Where to find source of C_pbinom?

[Marius Hofert]

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