Hi Sebastian,
You are doing a few things in a rather awkward manner. One thing is that you
still stick to what we call the 'classic' API; most of us think you probably
want the newer one. Have another look at the Rcpp-introduction vignette in
Rcpp 0.8.7 (maybe via the CRAN website). Also some of your R assignments
were, well, wrong as you were a little generous with the <-.
With that, here is a simple example using Rcpp and inline.
First, I (re-)define your helper function, making the argument const:
## define our helper function, this will be passed as an include segment to cxxfunction()
inc <- 'void other(const double any) {
+ std::cout << "YAY it works, value is " << any << std::endl;
+ }
+ '
Next, the body of the function. We get a double, once as a vector (which
will have length 1 of we pass a scalar as we do here -- recall that
everything is a vector in R) and once as a double.
## body of function: get scalar two different way, use it
src <- 'Rcpp::NumericVector vec = Rcpp::NumericVector(x); // as vector
We then make this a function in R using cxxfunction from inline:
library(inline)
fun <- cxxfunction(signature(x="numeric"),
+ body=src, inc=inc, plugin="Rcpp")
And use it:
num <- 42.1337
fun(num)
YAY it works, value is 42.1337
YAY it works, value is 42.1337
[1] 0
fun(3.1415)
YAY it works, value is 3.1415
YAY it works, value is 3.1415
[1] 0
For reference, the whole code is again below.
Hope this helps, Dirk
## define our helper function, this will be passed as an include segment to cxxfunction()
inc <- 'void other(const double any) {
std::cout << "YAY it works, value is " << any << std::endl;
}
'
## body of function: get scalar two different way, use it
src <- 'Rcpp::NumericVector vec = Rcpp::NumericVector(x); // as vector
double dbl = Rcpp::as<double>(x); // as double
other(vec(0));
other(dbl);
return Rcpp::wrap(0);
'
library(inline)
fun <- cxxfunction(signature(x="numeric"),
body=src, inc=inc, plugin="Rcpp")
num <- 42.1337
fun(num)
fun(3.1415)