On Thu, Dec 13, 2018 at 4:45 PM Alan Braslau <braslau.list@comcast.net> wrote:

Of course, it is:

double jn(int n,double x);

and

vardef jn(expr n, x) = scantokens(lua("mp.quoted( ffi.C.jn(" & decimal n & "," & decimal x & "))")) enddef ;

Alan

(shows that I have yet to use jn ;-)

I often use this as reference

source/texk/web2c/luatexdir/luaffi/test.lua

luigi